Ponomarenko et al. - Can psychedelics enhance group psychotherapy A di

Abstract

Background
Despite the growth of psychedelic research, psychedelic-assisted group psychotherapy (PAGP) has received little attention in comparison to individual psychedelic-assisted psychotherapy models.

Methods
In this article, we aim to discuss the therapeutic potential of PAGP, as well as outline existing models and the challenges of this approach. Using Irvin Yalom’s 11 therapeutic factors of group therapy as a basic framework, we analyse current literature from clinical studies and neurobiological research relative to the topic of PAGP.

Results
We argue that combining psychedelic substances and group psychotherapy may prove beneficial for increasing group connectedness and interpersonal learning, potentially enhancing prosocial behaviour with direct opportunities to practice newly acquired knowledge about previously maladaptive behavioural patterns. Challenges regarding this approach include a more rigid therapy structure and potential loss of openness from patients, which may be ameliorated by adequate therapeutic training.

Conclusion
We hope for this article to support clinical research on PAGP by presenting a therapeutic framework and outlining its mechanisms and challenges.

Full text

https://doi.org/10.1177/02698811231155117
Journal of Psychopharmacology
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Introduction
Social relationships are necessary for mental and physical health
(Umberson and Montez, 2010). People diagnosed with psycho-
logical disorders often react more aversively to social rejection
(Kumar et al., 2017) and may also encounter the stigma around
mental illness in society (Feldman and Crandall, 2007). If such
social dynamics of mental disorders are not actively addressed
within the course of psychotherapy, this may negatively influ-
ence the development, progression and treatment of the condi-
tion of patients. Individual psychedelic-assisted psychotherapy
(IPAP) has been introduced for the treatment of mental health
problems (Luoma et al., 2020). However, this therapy relies on
the patient’s own perspective and subjective reports of social
relationship difficulties that can be replayed and better under-
stood in the context of the therapeutic relationship, in which the
therapist can help identifying the patients’ contribution to these
difficulties and suggest alternative strategies. In contrast, psy-
chedelic-assisted group psychotherapy (PAGP) allows the
patient, other group members and the therapists to simultane-
ously experience and observe these difficulties in a safe and
supportive environment. This engages multiple perspectives
that may be therapeutic. In this article, we present a theoretical
framework for future research on PAGP to better understand its
potential benefits in treating social problems in addition to the
benefits of IPAP.
In the 21st century, only three empirical studies on group
therapy with psychedelics have been conducted (Anderson et al.,
2020; Oehen and Gasser, 2022; Schmid et al., 2021). However,
before the current wave of research, PAGP was extensively stud-
ied under the paradigm of psycholytic therapy (Passie, 1997). A
recent meta-analysis identified a total of 76 cases of PAGP, all
conducted between 1956 and 1995, in which a total of 700
patients in groups of up to 39 were treated with PAGP for
alcoholism, psychopathy, bipolar disorder, post-traumatic stress
disorder (PTSD), schizophrenia, depression, anxiety, phobias,
eating disorders and addiction (Trope et al., 2019). Significant
psychological and behavioural improvements were reported in
most cases, especially in combination with evidence-based
psychotherapeutic interventions and relatively high doses of
psychedelics.
Clinical interest in PAGP’s efficacy and potential advantages
is growing again (Beaussant et al., 2021). In this article, we
Can psychedelics enhance group
psychotherapy? A discussion
on the therapeutic factors
Polina Ponomarenko1, Federico Seragnoli2,
Abigail Calder3, Peter Oehen4 and Gregor Hasler3
Abstract
Background: Despite the growth of psychedelic research, psychedelic-assisted group psychotherapy (PAGP) has received little attention in comparison
to individual psychedelic-assisted psychotherapy models.
Methods: In this article, we aim to discuss the therapeutic potential of PAGP, as well as outline existing models and the challenges of this approach.
Using Irvin Yalom’s 11 therapeutic factors of group therapy as a basic framework, we analyse current literature from clinical studies and neurobiological
research relative to the topic of PAGP.
Results: We argue that combining psychedelic substances and group psychotherapy may prove beneficial for increasing group connectedness and
interpersonal learning, potentially enhancing prosocial behaviour with direct opportunities to practice newly acquired knowledge about previously
maladaptive behavioural patterns. Challenges regarding this approach include a more rigid therapy structure and potential loss of openness from
patients, which may be ameliorated by adequate therapeutic training.
Conclusion: We hope for this article to support clinical research on PAGP by presenting a therapeutic framework and outlining its mechanisms and
challenges.
Keywords
Psychedelic research, group therapy, psychotherapy, therapeutic factors, psychedelic-assisted group psychotherapy
1Faculty of Psychology, University of Bern, Bern, Switzerland
2 Addictology Department, Geneva University Hospital, Geneva,
Switzerland
3 Department of Medicine, University of Freiburg, Villars-sur-Glâne,
Switzerland
4 Private Practice for Psychiatry and Psychotherapy, Biberist,
Switzerland
Corresponding author:
Gregor Hasler, Department of Medicine, University of Freiburg, Chemin
du Cardinal-Journet 3, Villars-sur-Glâne, 1752, Switzerland.
Email: gregor.hasler@unifr.com
1155117JOP0010.1177/02698811231155117Journal of PsychopharmacologyPonomarenko et al.
research-article2023
Perspectives

2 Journal of Psychopharmacology 00(0)
examine the therapeutic factors of PAGP using current literature,
and we outline its advantages and disadvantages in comparison
with other methods, particularly IPAP. Our goal is to bring aware-
ness to this topic and illustrate how the conceptual framework of
Yalom’s 11 factors can further PAGP as an object of psychother-
apy research.
Group psychotherapy
Group psychotherapy is defined by Irvin Yalom (2005) as a social
therapy which gives its members the chance to interact with oth-
ers who can relate to their experiences. It is thought to ‘generate
a positive, self-reinforcing loop: trust–self-disclosure–empathy–
acceptance–trust’ (Yalom, 2005).
Today, group psychotherapy provides a solution to the prob-
lem of increasing psychotherapy demand by treating multiple
individuals simultaneously, thereby reducing wait list delays and
increasing accessibility and cost efficiency (Malhotra and Baker,
2022). While the group psychotherapy method is in itself very
diverse in relation to diagnoses and ways of conduct, it is found
to be particularly useful for homogeneous groups of patients
with similar conditions, therapeutic goals and therapy stages
(Burlingame et al., 2003; Malcolm et al., 2016; Wolgensinger,
2015). Research has demonstrated that group psychotherapy is an
effective method for treating a variety of psychiatric and behav-
ioural disorders, and experimental studies comparing individual
therapy and group therapy indicate that group therapy is about as
effective as individual therapy, although the great diversity of
approaches leads to heterogeneous results (Burlingame et al.,
2016; Cuijpers et al., 2008; Friedman, 2013).
Psychedelic substances
‘Psychedelic’ (or ‘mind-revealing’) substances are a class of psy-
choactive drugs which produce temporary and often dramatic
changes in perception, thought and emotion (Nichols, 2016).
Psychedelics are ingested at various doses, ranging from sub-
perceptual ‘microdoses’ to doses which produce strong altered
states of consciousness. Microdoses have not yet consistently
shown significant effects on well-being or in therapy (Polito and
Liknaitzky, 2022; Seragnoli et al., 2021), but higher doses have
been associated with lasting positive changes in psychopathology
and well-being (Gasser et al., 2015; Noorani et al., 2018). Classic
psychedelics, such as lysergic acid diethylamide (LSD) and
psilocin, share agonist action at the 5-hydroxytryptamine 2A
(5-HT2A) receptor (De Gregorio et al., 2021). Two other groups
of non-classical psychedelics include dissociative anaesthetics
such as ketamine and entactogens such as 3,4-methylenodioxym-
etamphetamine (MDMA), the latter of which produces psyche-
delic-like effects, predominantly an affective state of enhanced
mood, profound well-being, happiness, and increased extrover-
sion and sociability (Vollenweider, 2001). Due to its pro-social
effects, MDMA may be particularly suitable for group therapy.
MDMA increases synaptic levels of the monoamine neurotrans-
mitters serotonin, dopamine and norepinephrine and blocks their
reuptake, which is thought to be the primary source of its specific
psychological effect (Montgomery and Roberts, 2022).
Psychedelics are considered safe for clinical use. Classic
psychedelics have a very favourable safety profile, showing low
physiological toxicity and potential for dependency (Gable,
2004; Hasler et al., 2004; Johnson et al., 2008; Nutt et al., 2010).
Both classic psychedelics and MDMA can dose dependently
increase heart rate, blood pressure and body temperature (Holze
et al., 2022a; Vizeli and Liechti, 2017). They can also cause acute
psychological distress, which is usually manageable with inter-
personal support (Johnson et al., 2008). Serious adverse events
are rare in both healthy and clinical populations (Breeksema
et al., 2022), suggesting that well-trained therapists would likely
be able to manage adverse effects from psychedelics in a group
setting.
Set and setting
Psychedelics interact both with the mindset of the patients, other-
wise known as set, and the external conditions, otherwise known
as setting (Reiff et al., 2020). Like IPAP, PAGP requires a pre-
paratory phase to optimize these factors before administering any
psychedelics. Set refers to beliefs, attitudes, choices and motiva-
tions, and therapists must help their patients adopt a suitable
mindset before working with psychedelics (Schenberg, 2018;
Winkelman, 2021). In our experience, working on the set in a
group setting means not only that each individual establishes an
intention towards introspection, but also a strong focus on the
group’s intentions and processes. Conjointly, the setting should
be organized during the preparatory phase of therapy and refers
to the group’s atmosphere and environment, as well as the defini-
tion of the therapist role (Schenberg, 2018; Winkelman, 2021).
Setting also includes the social context and any instructions given
by the therapist, as well as the physical environment and the
choice of music. Music is nearly ubiquitous in psychedelic ther-
apy, even if the field still lack studies on it as a specific factor,
and it can provide emotional guidance and synchronicity within
the group (Winkelman, 2021). A safe and inviting atmosphere
has also been shown to reduce acute psychological distress
(Johnson et al., 2008) and may also help participants feel safe
within the often intense and chaotic nature of sensory and emo-
tional experiences in psychedelic sessions (Carhart-Harris et al.,
2018). In addition, the presence of other group participants can
increase physiological responses to psychedelics (i.e. heart rate),
as well as make the subjective drug effects more intense (Bershad
et al., 2016; Kirkpatrick et al., 2015).
One essential difference between conventional group therapy
and PAGP may be that PAGP accelerates the therapeutic process
of individuals within the group dynamic, without reducing the
amount of emotional experiences (Blewett, 1971). It does so by
adding emotionally intense, autobiographical and insightful psy-
chedelic experiences into the course of therapy, which are expe-
rienced and discussed together. Thus, PAGP holds the potential to
not only provide a socially supportive framework for therapy, but
also to shorten recovery time, potentially reducing both human
suffering and polypharmacy and drug dependency problems
(Brown et al., 2005).
Individual versus group psychedelic therapy
PAGP falls into the category of applied psychedelic research,
and it differs from current individual approaches (see Figure 1).
Psychedelic therapy, as it is currently used in clinical trials,
involves one to several high-dose sessions which are meant
to produce intense and profound psychedelic experiences

Ponomarenko et al. 3
(Schenberg, 2018). These may contain personal insights, belief
changes, emotional releases and transcendental ‘mystical’ expe-
riences which are viewed as therapeutically beneficial (van Elk
and Yaden, 2022). Psychotherapeutic integration sessions are
sometimes kept to the minimum required for ensuring safety,
though some researchers and clinicians have observed that psy-
chedelic substance intake without active therapeutic accompani-
ment is insufficient for clinical improvement (Read and
Papaspyrou, 2021). Patients often feel that their experiences
with psychedelic substances are difficult to describe to those
without first-hand knowledge, and if they have no one to relate
to, they may withdraw socially. Such reactions are not uncom-
mon even in healthy trial participants, and they have led to the
emergence of non-professional psychedelic integration groups
for past research participants (Noorani, 2019). Clearly, there is a
need for more professionally accompanied interpersonal sup-
port, and group psychotherapy would be uniquely able to pro-
vide it.
IPAP sometimes addresses this problem by combining indi-
vidual psychotherapy with a few introspection-focused sessions
with medium- to high-dose psychedelics (Richards, 2016), often
several months apart. Such interventions have been found to be
successful treatments for various psychiatric disorders (Luoma
et al., 2020), including treatment-resistant depression (Romeo
et al., 2020), anxiety disorders (Dos Santos et al., 2021; Holze
et al., 2022b), illness-related psychological distress (Gasser et al.,
2015; Griffiths et al., 2016), substance use disorders (Berlowitz
et al., 2019; Bogenschutz et al., 2022; Johnson et al., 2014) and
PTSD (Jerome et al., 2020; Mitchell et al., 2021). IPAP entails
preparatory and integrative sessions and is especially useful
when the patient needs a high level of support from the clinician,
for example, when working with complex disorders or a severe
fear of closeness and intimacy (Oehen, 2021). However, high-
dose sessions can last for many hours and are not only straining
for the therapist(s), but also very costly (Beaussant et al., 2021;
Teixeira et al., 2022; Vargas et al., 2021). Therefore, accommo-
dating the IPAP model on a large scale would seem to require
reconfiguring healthcare organization (Greenway et al., 2020).
Medical historians have pointed out that in the mid-20th century,
the laboriousness and costs of IPAP were disproportionally large
compared to other treatments (Richert and Dyck, 2020).
Another existing model is ‘psycholytic therapy’, which was
extensively researched in Europe in the mid- to late 20th century,
with over 300 studies published on this topic (Passie, 1997).
Later, it was adopted by the Swiss Medical Society for Psycholytic
Therapy (SÄPT) and is still being practiced. Psycholytic therapy
includes several sessions with different psychedelics, often in
groups and with a varying dose range (e.g. MDMA in the first
session, followed by a more intense session with LSD or a com-
bination of both) (Passie, 1997; Reiff et al., 2020). This approach
takes advantage of the different modes of substance action in
combination with evolving therapeutic processes, environments
and a greater access to the unconscious while discharging psy-
chic tension (Reiff et al., 2020). The focus of this therapeutic
approach is on remembering and understanding personal life
experiences as well as uncovering the inner functioning of
one’s mind. Preparation and integration at different intensity
levels involves more personal, psychodynamic and depth psy-
chology concepts (Jungaberle and Verres, 2008), rather than the
US-American humanistic, transcendental characteristics used in
IPAP, which primarily seeks to generate overwhelming peak
experiences (Reiff et al., 2020). While IPAP and PAGP approaches
can both be therapeutic, they require different forms of behaviour
from the therapist and patients. In our experience, PAGP tends to
bring the therapists into a more peripheral role with shared tasks
and responsibilities, because mutual support and feedback often
come from other group members.
Furthermore, in our experience with PAGP, we see a reduc-
tion in therapy costs for each patient because therapists can split
the costs among all participants of the group. These costs include
Figure 1. Psychedelic use in applied research.

4 Journal of Psychopharmacology 00(0)
the therapists’ work time, use of the therapeutic space, and, from
the patients’ perspective, the cost of transportation. The group
setting is also both more rewarding and more cost-efficient than
individual sessions for most problems treated with psychedelic
therapy (Oehen, 2013).
Different PAGP models
Several different frameworks for PAGP have been attempted in
the past, and we would briefly outline them here. PAGP is rooted
in social and ritualistic psychedelic consumption, which has been
central in many cultures throughout human history (Winkelman,
2010). Today, such group ceremonies are used safely for reli-
gious purposes in both healthy and clinical populations (Halpern
et al., 2008). Combinations of ritualistic and therapeutic use are
also emerging, the most prominent example of which is aya-
huasca-assisted therapy for addiction, in which study participants
take part in ayahuasca ceremonies in retreat centres (Thomas
et al., 2013).
Psycholytic therapy has been studied and practiced since the
middle of the 20th century, and it has reported success in reduc-
ing psychopathology (Passie, 1997). It has not only involved psy-
chedelic sessions in combination with regular group
psychotherapy, but also other methods, including art therapy
(Leuner, 1981). In one early example from 1961, PAGP was
practiced with 166 heterogeneous patients in groups of 7–10
(Fontana, 1961; Trope et al., 2019). Psychoanalytic group ther-
apy was carried out on a weekly basis and psychedelic-assisted
sessions with a medium dose of LSD (50–150 μg) or psilocybin
(8–12 mg) were performed monthly. After the treatment, Fontana
(1961) concluded that 93 out of 166 patients were ‘cured’ or had
improved significantly.
Another very different framework has been described in a
study of ‘Permissive Group Therapy’, in which the author exam-
ined a group of 10 female participants diagnosed with ‘hopeless
cases of chronic psychopathy, hysteria, phobic anxiety or recur-
rent neurotic depression’ (Spencer, 1963; Trope et al., 2019).
Using a group therapy program that many would find questiona-
ble today, patients were given very high LSD doses of up to
1500 μg twice a week for 16 months. The sessions took place in a
‘child guidance play therapy room’ and allowing the patients to
use the toys and dummies to represent parental figures during the
sessions. The high dosages were explained by the patients’ devel-
oped resistance to LSD. After the treatment, Spencer (1963)
stated that three patients had ‘improved sufficiently to require no
further psychiatric help’ and with another four patients the treat-
ment ‘helped to a fairly definite degree’.
In the 21st century, three studies have been published on
PAGP, which are summarized and compared in Table 1. In the
Swiss limited medical use program from 2014 to 2018, a total of
18 patients (12 women, 6 men; median age: 49 years) were
treated with LSD and MDMA over several years in open group
settings (Schmid et al., 2021). Drug-assisted sessions were
3.5 months apart, with 3–10 psychotherapy sessions in between
them. The groups varied in size between 3 and 13 participants,
with 1–3 trained psychiatrists and/or psychotherapists. The set-
ting of the LSD- and MDMA-assisted group psychotherapy ses-
sions consisted of a quiet meditative atmosphere, and music was
played for about one-third of that time (Schmid et al., 2021).
Drug administration generally started in the morning around
10 am in group sessions, during which participants were
administered varying substances and doses and were encouraged
to experience the first hours of the substance effects in introspec-
tive silence (Gasser, 2017). The group session finished around
6 pm, after which the participants were free to take time for them-
selves. An integration group session would follow the day after,
before letting the patients return to their homes.
Ongoing PAGP is still conducted in Switzerland under the
Swiss limited medical use program using a model that includes
group preparation, drug administration and integration. Group
therapy accompanies the individual psychotherapy program of
each patient and uses the so-called ‘3-day-format’ on the week-
ends: one group psychotherapy session takes place Friday even-
ing, followed by the psychedelic-assisted session beginning on
Saturday morning and the integration session on Sunday. While
the substance-assisted sessions are held in one room for the entire
participant group of up to 12 people (with three therapists),
another separate room is available if a patient needs a moment of
privacy with one of the therapists (Gasser, 2022; Oehen and
Gasser, 2022).
Another recent study on PAGP was conducted at the
University of California and consisted of three group therapy
cohorts, each consisting of six gay-identified male participants
(age: 50–66 years) with an HIV diagnosis and moderate-to-severe
demoralization (Anderson et al., 2020). The procedure began
with four group therapy sessions prior to one individual psilocy-
bin-assisted session (0.3–0.36 mg/kg doses, 8-h duration), all of
which were supported by two clinical therapists in each cohort.
The day after the substance intake, each participant attended an
individual integration session. In the following weeks, all partici-
pants attended 4–6 additional group therapy sessions. The total
length of treatment was 7 weeks, including 12–15 h of group psy-
chotherapy (Anderson et al., 2020). Clinically meaningful reduc-
tions in demoralization were observed following the group
psilocybin session, and they persisted at a 3-month follow-up.
These studies suggest that PAGP can be effective for both
homogeneous and heterogeneous patient groups, and within both
fixed and open-ended time frames. In addition, different treat-
ment models showed clinical efficacy. In the study of HIV-
positive men, psilocybin-assisted therapy was conducted
individually with only the integration session being in groups. In
the other studies, LSD and MDMA sessions took place in the
group setting, while some therapy sessions were individual. The
main outcomes of the two studies that measured clinical varia-
bles showed significant improvements.
Furthermore, there are two ongoing pilot trials on psilocybin-
assisted group therapy to treat cancer-associated major depres-
sive disorder (NCT 04593563, NCT 04522804). The first is an
8-week project in which a total of 30 participants receive a single
group substance-assisted session combined with one-on-one psy-
chological support (Ross et al., 2022). The second study includes
12 participants in two cohorts and consists of a total of seven
group therapy sessions, including three 2-h preparatory sessions,
one 8-h psilocybin session and one 2-h integration session (Ross
et al., 2022).
Outside of research studies, PAGP models have been applied
to ketamine in clinical practice and have included mostly homo-
geneous groups of patients. Patients come once a month for
4 months, or once every 3 months for a year. After a preparatory
session, the first psychedelic session involves low-dose oral keta-
mine to ensure safety and comfort. In the second session, the dos-
age gradually increases, and the third and last session includes a

Ponomarenko et al. 5
Table 1. Summary of the PAGP studies published since 2000.
Therapy approach Psilocybin-assisted group therapy LSD- and MDMA-assisted group psychotherapy LSD- and MDMA-assisted group psychotherapy
Study design Single-arm, open-label, pilot study Swiss compassionate use program, prospectively designed study Swiss compassionate use program
Substance dose Crystalline oral psilocybin; 0.3–0.36 mg/kg MDMA: absolute oral doses of 100 and 125 mg
LSD: absolute oral doses of 100, 150, 175 and 200 μg
Beginning with MDMA and transitioning to LSD in later therapy
stages
MDMA: absolute oral doses of 100 and 125 mg
LSD: absolute oral doses of 100, 150, 175 and 200 μg
Beginning with MDMA and transitioning to LSD in later
therapy stages (except when it was not trauma-related)
Total duration Intervention: 7 weeks
Follow-up: 3 months, 6.5 months, 3.2 years,
4.5 years
Ongoing therapy over a period of 4 years Ongoing therapy over a period of 5 years
Total hours of therapy 3 h of individual psychotherapy,
12–15 h of group psychotherapy,
1 × 8-h individual psilocybin administration
Ongoing regular individual psychotherapy
Mean drug-assisted sessions ± 5.7 (SD ± 0.8),
Time in between sessions: on average every 3.5 months after
attending 3–10 non-drug psychotherapy sessions
Ongoing regular individual psychotherapy with one of the
therapists,
Time in between sessions: 2–4 months
Total number of
participants, group size,
number of therapists
18 participants in total
18 participants per group
2 therapists per group
18 participants in total
3–13 participants per group
1–3 therapists per group
50 participants in total,
Max. 12 participants per group
3 therapists per group
Inclusion criteria (1) Gay-identified, English-speaking
cisgender men >50 years old and living
with HIV
(2) Self-report of HIV diagnosis prior to
the clinical availability of protease
inhibitors
(3) Moderate-to-severe demoralization
Assessed by a Demoralization Scale-II
(DS-II)
PTSD (61 %)
Major depression (22 %)
Others including (1–2 participants): anxious personality disorder,
narcissistic personality disorder, OCD, dissociative disorder, bulimia,
autism spectrum disorder, social anxiety disorder, psychogenic
aphonia, cluster headache, life-threatening disease, substance
abuse disorder, suicidal tendencies
50% of participants were on medications during treatment
(antidepressants, anxiolytics, neuroleptics)
Treatment resistance in the case of trauma-related disorders:
PTSD/c-PTSD/dissociative disorder (46%)
Depression (20 %)
Anxiety disorders (20 %)
Cluster headache (10 %)
OCD (4 %)
ASD (4 %)
Other medications (antidepressants, neuroleptics) had to be
discontinued 1–2 weeks before the psychedelic session
Somatic medications (antihypertensive drugs, thyroid
preparations or anti-Parkinson’s medication) were continued
Exclusion criteria Adapted from current standard criteria for
psilocybin administration (Johnson etal.,
2008)
Patients with psychotic disorders or unable to attend group
meetings
BPD, a history of psychotic episodes, BP in patients and in
first-degree relatives; acute drug dependency
Main outcomes After 4.5 years:
(1) Significant reductions in
demoralization, hopelessness, death
anxiety (HADS, STAI, Beck scales)
(2) Significant increase: faith, spiritual
well-being
(3) 96 % rated the experience the single
or top five most spiritually significant
experience(s) of their lives
(4) 100% reported ‘moderate’, ‘strong’ or
‘extreme’ positive behavioural change
towards the psilocybin experience
Immediately after sessions:
(1) LSD induced pronounced alterations of waking consciousness
with significant increases in all dimensions and all subscales of
the 5D-ASC
(2) LSD produced a mystical-type experience with significant
increases in all MEQ scales
(3) LSD produced similar effects in patients and healthy controls
(4) MDMA produced significant increases in all dimensions of the
5D-ASC except for ‘auditory alterations’; overall less pronounced
effects than LSD
(5) MDMA produced significant increases in all MEQ scales except
for ratings of ‘internal unity’
(6) MDMA produced greater effects in patients than healthy controls
End of reporting period:
(1) Clinically improved: trauma-related disorders (62%),
anxiety disorders (50%), depression (40%), ASD (50%),
cluster headache (20%)
(2) 60% of participants terminated psychotherapy after this
treatment
Source (Anderson etal., 2020; Agin-Liebes etal.,
2020)
(Schmid etal., 2021) (Oehen and Gasser, 2022)
ASD: autism spectrum disorder; BPD: borderline personality disorder; ; HADS: Hospital Anxiety and Depression Scale; LSD: lysergic acid diethylamide; MDMA: 3,4-methylenodioxymetamphetamine; MEQ: The Mystical Experience Questionnaire;
OCD: obsessive-compulsive disorder; PAGP: psychedelic-assisted group psychotherapy; PTSD: post-traumatic stress disorder; ; STAI: The State-Trait Anxiety Inventory; 5D-ASC: five-dimensional Anxiety Scale for Children.

6 Journal of Psychopharmacology 00(0)
high-dose intense dissociative experience in which participants
flexibly choose when to communicate with each other. The fourth
session gives space for communal integration (Lawlor, 2021).
Contraindications
Specific contraindications for PAGP need more investigation and
have thus far differed between PAGP studies. General exclusion
criteria for any psychedelic treatment currently include preg-
nancy or breastfeeding, cardiovascular diseases, certain medica-
tions, and a history of schizophrenia or other psychotic disorders;
these are further specified elsewhere (Johnson et al., 2008).
PAGP-specific contraindications mentioned in the literature
include borderline personality disorder (Anderson et al., 2020;
Oehen and Gasser, 2022), bipolar disorder in patients and in first-
degree relatives, acute drug dependency (Oehen and Gasser,
2022) and severe lack of social skills (Gasser, 2022). In the long-
term practice of PAGP in Switzerland, no other specific contrain-
dications to PAGP have been documented. Though PAGP in
Switzerland still occurs on a relatively small scale, it appears to
be safe when following the abovementioned guidelines.
Analysis
In this article, we use the term ‘psychedelic experiences’ to refer
to the altered states of consciousness induced by psychedelics,
including their varying phenomenological descriptions from both
the ‘psychedelic’ and the ‘psycholytic’ schools. This includes
general patterns of the ‘unconstrained mind’ (Lifshitz et al.,
2018) embedded in subjective changes in affect, time, space,
embodiment and empathy (Preller and Vollenweider, 2018), as
well as what some would call ‘mystical experiences’ and the
insights drawn from their contents (Yaden and Griffiths, 2021). It
can also encompass the gradual softening of the autobiographical
self (or ‘egolysis’) (Guss, 2022) and its more extreme version of
‘ego dissolution’ at high doses (Lifshitz et al., 2018; Milliere,
2017; Preller and Vollenweider, 2018).
When discussing PAGP, we also group two possible PAGP
frameworks together: (1) traditional group therapy with the addi-
tion of substance sessions and (2) individual psychotherapy with
only the substance sessions in groups (Oehen, 2021). To our
knowledge, specific differences in the effectiveness of these two
approaches have not been studied yet. Furthermore, the PAGP
process often starts with individual psychotherapy because
patients may fear opening up to the other group participants, or
they may worry about the unfamiliarity of psychedelic experi-
ences (Oehen and Gasser, 2022). A flexible approach between
individual and group sessions may be useful to give patients
additional support, build hope and strengthen the therapeutic alli-
ance. We also do not distinguish between specific psychothera-
peutic traditions, focusing instead on general group therapeutic
factors (Gukasyan and Nayak, 2021).
In this review, we examine PAGP through the lens of Yalom’s
11 therapeutic factors within ‘Theory and Practice of Group
Psychotherapy’ (Yalom, 2005). This extensive model on group
psychotherapy is widely accepted and influential, and it builds
the basis for many clinical group therapy frameworks (Behenck
et al., 2017; Chouliara et al., 2020; Reddy, 2015). The 11 factors
which play a major role in group therapy are the following:
1. Instillation of hope
2. Universality
3. Imparting information
4. Altruism
5. Corrective recapitulation of the primary family group
6. Development of socializing techniques
7. Imitative behaviour
8. Interpersonal learning
9. Group cohesiveness
10. Catharsis
11. Existential factors
Taken together, these factors represent a theoretical categori-
zation of the curative aspects of all types of group therapy and are
thought to affect patients positively when in therapeutic focus
(Malhotra and Baker, 2022).
To gather information for the discussion of each therapeutic
factor regarding PAGP, we focused our research on clinical trials
and neurobiological research, as well as supplemental informa-
tion from experienced practitioners in this field. We searched the
databases of Google Scholar and PubMed from October 2021 to
December 2022. Additional information was taken from selected
chapters of relevant books.
Yalom’s therapeutic factors in PAGP
Instillation of hope
The installation of hope unfolds in two directions. First, it is the
patient’s belief in their own capability for overcoming their ill-
ness. Second, it is belief in the effect of the therapy itself. Both
are required for the patient to stay in therapy, and they are there-
fore the most crucial factors (Yalom, 2005).
Sometimes, the increased affectivity and insights derived
from psychedelic sessions can bolster patients’ belief that recov-
ery is possible. Increased belief in one’s power to recover has
been seen in patients’ experiences with psilocybin and MDMA in
multiple studies (Breeksema et al., 2020; Noorani et al., 2018;
Watts et al., 2017). Psychedelics can also enhance autobiographi-
cal memory recollection (Baggott et al., 2016), through which
patients may realize the depth, complexity and nuances of his or
her personal life story. This may help patients to broaden their
autobiographical perspective, bolstering both hope and motiva-
tion for recovery. In qualitative interviews conducted by Passie
(2012), PAGP patients have described revisiting experiences,
people and events from their past, together with an emerging
sense of deep primal trust in their own capabilities and in the
world at large. These realizations have been particularly associ-
ated with challenging experiences, adding a sense of curiosity in
painful moments, as if patients anticipate the coming relief.
In addition, PAGP patients benefit from witnessing and empa-
thizing with the success of other group members, which may be
augmented by psychedelics’ capacity to enhance emotional
empathy (Dolder et al., 2016; Pokorny et al., 2017; Schmid et al.,
2014). The success of others can inspire patients to envision
following a similar path and realize their own self-efficacy, simi-
lar to the effects witnessed in other group therapies (Johnson and
Sullivan-Marx, 2006).

Ponomarenko et al. 7
Universality
The concept of universality addresses the patient’s feeling ‘that
they are unique in their wretchedness’ (Yalom, 2005). As group
members begin to disclose these concerns, they create the oppor-
tunity to relate to each other. Yalom (2005) describes this process
as a ‘welcome to the human race’ experience. Its ultimate stage is
the realization that there is no human deed or thought that is for-
eign to others.
Without the feeling of universality, there is often an increased
focus on one’s own mental state, greater negative self-attribution
and rumination, and reduced attention to others. This can result in
social isolation and difficulties in interpersonal relationships. In
sharing their experiences within a structured group environment,
however, patients start to understand that others share similar
thoughts, feelings and problems. As the PAGP therapist Raquel
Bennett observes,
In individual treatment, people often felt very alone, that they
were the only person on earth dealing with whatever problem
they were living with. In the group, people quickly found that
there were other people who had similar issues and challenges
(Lawlor, 2021).
A recent qualitative analysis of PAGP reports a reduction in
this habitual self-focus, leading to a sense of belonging and inter-
dependence in the majority of patients (Agin-Liebes et al., 2021).
This suggests that treatment with psychedelics in a group setting
can help to develop the feeling of universality.
Though group therapy alone can reduce feelings of unique-
ness, psychedelics may amplify this effect. Psilocybin has been
shown to catalyse experiences of unity, in which people feel like
they are one with other people or their surroundings (Preller
et al., 2016). Psychedelics are also known for their ability to tem-
porarily eliminate the subjective feeling of having a self, some-
times referred to as ego dissolution, which people often describe
as the feeling of becoming ‘one’ with other people or the environ-
ment (Nour et al., 2016). Psychedelics may cause ego dissolution
by altering the functional connectivity of the default mode net-
work (DMN), which is implicated in self-referential processing
(Carhart-Harris et al., 2016; Mason et al., 2020; Palhano-Fontes
et al., 2015; Tagliazucchi et al., 2016). Without the self, there can
be no exaggerated focus on one’s individual mental state. This
may be particularly therapeutic in patients suffering from depres-
sion, for which perceived uniqueness of one’s suffering is a
prominent feature. Depression is also hypothesized to correlate
with an overly active DMN and executive network (Vollenweider
and Smallridge, 2022).
Group therapy alone can increase feelings of universality, and
psychedelic-induced changes in beliefs about the nature of reality
can do the same. Put together, we theorize that they complement
each other: Interactions with other group members offer insight
into the problems they have in common, and psychedelics allow
patients to temporarily step outside of themselves, both of which
work to reduce focus on one’s own individual suffering.
Imparting information
During group therapy, both the therapists and other patients may
share information about mental health, mental illness and general
psychological dynamics, as well as advice, suggestions or direct
guidance (Yalom, 2005). These processes constitute the thera-
peutic factor of imparting information.
Group therapy with psychedelic substances includes an addi-
tional source of information, apart from therapists and other
patients: the personal insights derived from psychedelic experi-
ences themselves. Patients often describe these in terms of learn-
ing experiences, and they can feel like they have acquired
important information about themselves, their mental habits and
their capabilities (Breeksema et al., 2020; Wolff et al., 2020). As
participants undergo these experiences, the psychedelic therapist
can support, orient and deepen the process. This is crucial because
learning experiences on psychedelics are sometimes painful;
psychedelics tend to intensify therapeutic processes, occasionally
leading to challenging experiences for the patient (Carbonaro
et al., 2016; Roseman et al., 2018b). In group therapy, all learning
experiences can be processed and shared within the group,
including challenging ones, and participants can be supported by
both the therapists and their peers. Because PAGP encompasses
both expression-oriented phases and introspection-oriented
phases within the psychedelic session (Jungaberle and Verres,
2008), patients can benefit from both.
Altruism
According to Yalom (2005), the members of a therapy group
profit not only from receiving help, but also from the intrinsic
motivation to give something back. Giving tends to remedy the
feeling of ‘being a burden’ and it can bring back a sense of useful
contribution, value and meaning in life. The opportunity for
reciprocal interactions offers a unique process to patients in
group therapy, which they often use and benefit from.
Psychedelics tend to enhance prosocial feelings and behav-
iour. In particular, MDMA has increased self-reported feelings of
sociability across multiple placebo-controlled trials, with moder-
ate to large effects on extraversion, friendliness and trust (Regan
et al., 2021; Schmid et al., 2014). MDMA may also increase emo-
tional empathy and prosocial behaviour (Hysek et al., 2014),
though some environments may not be conducive to these effects
(Borissova et al., 2021). LSD and psilocybin are also known to
increase emotional empathy and sociality (Dolder et al., 2016;
Pokorny et al., 2017; Schmid et al., 2014), and psychedelics may
make it easier to see things from another’s perspective (Thal
et al., 2021).
Studies also indicate that reciprocity and altruistic behaviour
are more prominent when the other person is a friend, and not a
stranger (Kirkpatrick et al., 2015; Kuypers et al., 2014). In PAGP,
participants have the opportunity to become familiar with each
other during multiple therapy sessions and often form friendships
even outside of the therapy group. In addition, Preller and
Vollenweider (2019) stated that after psychedelic interventions
altruistic behaviour occurs predominantly in participants with
low altruism at baseline, which may be of particular interest in
clinical populations, as altruism and other prosocial behaviour
resulting after psychedelic therapy have been documented as
long-term outcomes in a clinical addiction study (Noorani et al.,
2018).
With MDMA, these effects may partly depend on action at the
serotonin transporter within the nucleus accumbens (Curry et al.,
2019; Heifets et al., 2019; Kamilar-Britt and Bedi, 2015; Mukai
et al., 2020). In addition, both MDMA and classic psychedelics
increase oxytocin levels (Holze et al., 2019, 2022c; Nardou et al.,

8 Journal of Psychopharmacology 00(0)
2019). Oxytocin likely facilitates many prosocial behaviours,
including altruism, cooperation, caring for others and trust
(Marsh et al., 2021).
From these results, we hypothesize that in PAGP, psyche-
delics promote altruism in patients’ interactions with each other.
Patients may experience more feelings of empathy, as well as
perspective shifts and other prosocial impulses, which they can
directly put into practice in the group setting with people they
have come to know relatively well.
The corrective recapitulation of the primary
family group
Yalom (2005) describes the resemblance of the therapy group to
a family structure, often triggering implicit memories of negative
experiences in the primary family of the patient. This causes dis-
comfort at first, but once overcome, interacting with other group
members in the mimicry of their primary family patterns leads to
therapeutically important realizations. While this may also hap-
pen in individual therapy, the group dynamic tends to enhance
this effect, revealing initial behavioural patterns and allowing
them to be re-lived in a corrective manner.
An emotionally positive psychedelic group experience, in
which participants are open, caring and emotionally close to each
other, has the potential to be a corrective learning experience.
The group can serve as a model for a loving and supportive pri-
mary family group. This is especially beneficial for victims of
childhood neglect and violence who have few memories and
imprints of a positive familial atmosphere. In addition, because
psychedelics improve autobiographical memory (Carhart-Harris
et al., 2012; Garcia-Romeu and Richards, 2018; Healy, 2021),
patients may have freer access to relevant memories concerning
family relationships. Throughout PAGP, patients can develop a
new standard for a healthy family structure, discovering that they
are able to express and receive love and kindness both during
therapy and afterwards.
From experience, Oehen and Gasser (2022) observe that ‘pre-
conscious conflicts and ineffable childhood dramas tended to be
re-enacted in the group’ and that such effects, though possible
within any group therapy, can be enhanced by PAGP. They go on
to describe a case study:
[. . .] after being in intensive psychotherapy for more than
1 year she had her first MDMA experience in a group setting.
She labelled it an ‘emotional breakthrough’ and [experienced]
positive and negative emotions of previously unknown
intensity [. . .]. In the group, she befriended a fellow patient
and developed a sister-transference to her. The processing of
this transference reaction was very important to overcome her
chronic feelings of guilt toward her biological sister and to
gain independence, self-worth, and authenticity. This led to
her being able to interact with her fellow patient (and the
others) in a good and increasingly mature way, with clear
boundaries.
However, problematic group dynamics, which reinforce dys-
functional behavioural patterns, can also occur within group psy-
chotherapy and have also been observed in the Swiss limited
medical use program of PAGP. Such dynamics could sometimes
last for several sessions until they were appropriately addressed
and dealt with by the therapists. Nevertheless, such problems
have not thus far led to an overall negative outcome or a rein-
forcement of dysfunctional patterns in individual participants.
From today’s perspective, this therapeutic factor can be
extended towards not only the primary family group and the indi-
viduals’ unconscious inner systems of tension or COEX systems
(systems of condensed experience) (Grof, 2000), but also to any
other autobiographical memories of relational nature. This could
be part of the general phenomenon that psychedelics disrupt psy-
chological habits, fixed cognitions and other constraints or ‘pri-
ors’ which limit one’s thinking (Carhart-Harris and Friston, 2019;
Swanson, 2018). Patients may gain an increased awareness of
avoidance tendencies in difficult social situations (Gasser et al.,
2015), potentially allowing them to process frightening stimuli in
a relatively unconstrained mind (Frecska, 2011), yet still within
the supportive framework provided by other group members and
therapists. This could allow for a more open and positive conver-
sation about traumatic memories in the integration sessions.
Development of socializing techniques
The development of basic social skills is a crucial therapeutic
factor present in group therapy, although it varies greatly depend-
ing on group goals. To promote this, therapists can use both direct
techniques (e.g. role-play) and indirect, dynamic techniques (e.g.
interpersonal feedback) (Yalom, 2005).
In addition to the effects on pro-social behaviour discussed
above, psychedelics may also benefit the development of social
behaviour via changes in mood (Preller and Vollenweider, 2019).
Psychedelics tend to enhance positive mood, as well as reduce
the response to negative facial expressions and increase goal-
directed behaviour towards positive compared to negative cues
(Kometer et al., 2012; Preller and Vollenweider, 2019; Rocha
et al., 2019; Roseman et al., 2018a; Wardle and de Wit, 2014).
MDMA also enhances ratings of pleasantness for affective touch
(Bershad et al., 2019) and significantly increases the emotional
and social content of spontaneous speech, emotional disclosure
and comfort with describing emotional memories (Baggott et al.,
2016; Bershad et al., 2016). Such findings are hypothesized to
lead to an increased social interest (Bedi et al., 2010), more
acceptance of group interactions and increased responsiveness to
therapeutic interventions from the clinician. These pro-social
effects outlast the acute drug effects (Noorani et al., 2018), mean-
ing that socializing techniques may be of benefit in the integra-
tion sessions.
Psychedelic intake may also make patients less sensitive to
social exclusion. After exposure to MDMA or psilocybin, partici-
pants in one study showed reduced feelings of social exclusion in
the CyberBall task, as well as a significant reduction in activation
of the right anterior mid-cingulate cortex, a key region for social
exclusion processing (Frye et al., 2014; Preller et al., 2016).
Psychedelics may therefore reduce social pain processing, which
is associated with changes in self-experience. During therapy,
patients may therefore take social pain less personally, which
may provide an opportunity to reflect more mindfully on social
behaviour. Adding to this, MDMA interventions have been
reported to reduce interpersonal defensiveness (Bedi et al., 2009;
Mithoefer et al., 2011; Oehen et al., 2013), which may help
patients to break out of the blaming communication style and
begin to open up and reconnect to others.

Ponomarenko et al. 9
Imitative behaviour
During group therapy, patients have the tendency to imitate not
only the behaviour of the therapist, but also that of other group
members when learning how to address problems (Yalom, 2005).
This therapeutic effect generally plays a more prominent role in
the beginning of therapy and lessens after a while, as patients
determine the usefulness of the mimicked behaviours and decide
whether to adapt them long-term or not.
Imitative behaviour in PAGP has often been described, but its
effects are not yet entirely understood. Eric Osborne, the founder
of a psychedelic retreat centre, states
Within the direct experience, how many times we have seen
the release of someone in the group, possibly even at a
distance, that has impact on others within the group and
feeling OK to just let it go. [. . .] We have instances where
someone’s outburst or emotional release will trigger someone
else’s. (Osborne and Townsend, 2020)
Because psychedelics can increase empathy (Holze et al.,
2021; Mason et al., 2019), group members may become more
aware of the distress of others in the group. If they then mimic the
perceived behaviour, they may find themselves seeking an expla-
nation for it within their own functioning. This may, in turn, help
them in the process of identifying their own disturbing emotions
and follows a corrective adjustment in the gradually evolving
environment of the PAGP setting (Blewett, 1971).
Passie and Dürst (2008) analysed interviews of patients after
PAGP and summarized multiple examples of members going into
the social ‘roles’ of other members during the psychedelic inter-
ventions. Through this imitative behaviour, they were said to be
exploring other gender, family or work roles, thereby empathiz-
ing even with members that seemed to have completely different
situations from themselves (Passie, 2012). In summary, imitative
behaviour has been documented in relation to PAGP, though
more research is needed to analyse this phenomenon and its use-
fulness in more detail.
Interpersonal learning
Yalom (2005) explains this complex therapeutic factor by divid-
ing it into three main concepts. First, all members must under-
stand the importance of interpersonal relationships for health and
well-being. Second, patients should have corrective emotional
experiences which disconfirm the pathogenic beliefs arising from
negative memories of previous social interactions. Lastly, inter-
personal learning experiences will develop into a social micro-
cosm over time, in which group members will continuously
become more comfortable with expressing themselves. As this
occurs, they will begin to reveal more maladaptive interpersonal
behaviour, which can then be addressed accordingly.
During PAGP, psychedelics may augment corrective emo-
tional experiences. A recent clinical study of PAGP in patients
with moderate-to-severe demoralization observed a significant
reduction in attachment anxiety 3 months after psychedelic inter-
vention (Stauffer et al., 2021). Other PAGP patients also reported
overcoming previous emotional boundaries, resulting in new-
found feelings of connectedness with other group members and
loved ones during and after the psychedelic intervention. During
the treatment and integrative therapy, nearly all participants rec-
ognized destructive unconscious habits and previously ineffec-
tive coping strategies. In semi-structured interviews, they
described an augmented capacity to recognize these past patterns,
and this awareness made them feel acceptance, forgiveness and
relief. They also acquired a more flexible, multidimensional
understanding of themselves and new self-narratives, which
aided them in their interactions with other group members, as
well as with loved ones (Agin-Liebes et al., 2021).
Another study on PAGP also mentions the therapeutic poten-
tial of interpersonal learning, whereby processing shame (e.g.
from being a victim of sexual abuse) in the group setting seemed
more difficult for some participants. Validation from other mem-
bers was reportedly helpful, and it both reduced the feeling of
having a unique struggle and promoted learning experiences
(Anderson et al., 2020). Similarly, interpersonal support can be a
powerful amplifier of therapeutic results during PAGP, positively
affecting attachment security (Stauffer et al., 2021) and giving
instant opportunities to act on newly acquired insights, thereby
deepening the learning process (Passie and Dürst, 2008). Gasser
(2022) found that PAGP can improve patients’ psychedelic expe-
riences, particularly during difficult moments in their sessions.
These difficult moments may include the emergence of negative
memories, strong emotions or changes in beliefs. PAGP provides
a supportive community that can help individuals navigate these
personal challenges and may also highlight commonalities in
their unconscious conflicts and relationship dynamics. In this
way, group members may experience both a network of support-
ive relationships and become a role model themselves (Gasser,
2022).
Furthermore, psychedelics may amplify learning processes in
general through their effects on neuroplasticity. Neuroplasticity
denotes the brain’s ability to modify its connections in an adap-
tive manner, and it underlies learning of all kinds (Sasmita et al.,
2018). Classic psychedelics, MDMA and ketamine have all been
shown to lastingly enhance the growth of dendrites and synapses
in the neocortex, including in areas relevant for emotional regula-
tion (Calder and Hasler, 2022; Ly et al., 2018). Though research
on learning is still sparse, there is some indication that psyche-
delic intake benefits certain types of learning, including reversal
learning and reward learning (Buchborn et al., 2014; Gimpl et al.,
1979; Kanen et al., 2022; King et al., 1974; Romano et al., 2010).
Group learning processes occurring in PAGP could potentially be
amplified by these physiological effects.
Group cohesiveness
Yalom (2005) defines cohesiveness as the group therapy ana-
logue to the therapeutic relationship in individual therapy,
although it is more complex because more people are involved. A
strong and positive bond, as well as the ability to constructively
deal with conflict within the group, is important in altering cogni-
tive distortions and loosening maladaptive beliefs. Group cohe-
siveness is seen as a precondition for the other factors to function
optimally.
Cohesion develops as patients increasingly participate in the
group. They begin to influence each other and allow themselves
to be influenced, they listen to and accept others, they self-dis-
close and learn to feel secure, and they protect group norms and
resist disruptions. PAGP is a long-term project, because these

10 Journal of Psychopharmacology 00(0)
things take time to develop. Oehen and Gasser (2022) describe
how this process might look:
Over time a core group of participants who continuously
attended psychedelic-assisted sessions was formed. They also
began to meet and provide mutual support outside of the
therapy, and new friendships developed. The more advanced
they were in their individual long-term therapeutic process
the more they engaged directly in supporting and confronting
their peers during the sessions in a co-therapeutic sense, as
well as taking care of and serving as a model for newcomers,
helping to experience what secure attachment, mutual
responsibility and care for each other really mean.
This holds imperative value during PAGP, as group sessions
with psychedelic substances can improve trust (Schmid et al.,
2014) and the ability to connect in a social context, potentially
leading to long-lasting and healthy relationships (Kettner et al.,
2021; Roseman et al., 2021). MDMA in particular has been
found to act as a social catalyst in group settings, amplifying
facets of group connectedness (Regan et al., 2021). Blewett
(1971) points out that during PAGP, interpersonal connection
seems to be relatively free of distortions and empathic bonding
occurs with more direct, clear communication. A frequent cause
of criticism and conflict within the PAGP group is when partici-
pants start communicating inauthentically and hiding feelings
during the group exchange, in which case it is often the more
experienced members that begin the confrontation spontane-
ously to re-establish cohesiveness. It is advisable for the conflict
to be declared before the psychedelic session so that the resolu-
tion can come during the sharing phase, when participants are
usually more open and compassionate with each other (Oehen
and Gasser, 2022).
The PAGP study by Agin-Liebes et al. (2021) also concludes
that after the psychedelic intervention, group members express
more feelings of openness and relaxation while being in the
group, even if this had not been so just before the session. Other
effects included enhanced emotional safety and more willingness
to process painful emotions in the group. In addition, patients
may feel closer to each other simply by virtue of having shared a
psychedelic session: people often find psychedelic effects hard to
describe to others who have not experienced them, and the other
PAGP group members therefore have a relatively unique capacity
to understand each other’s experiences (Nielson et al., 2018;
Pedersen et al., 2021).
Connectedness to other members seems to come quickly for
some participants, and peer support is described to be especially
helpful for tolerating and understanding the content and insights
derived from psychedelic experiences (Anderson et al., 2020).
Gasser (2022) also elaborates on the fact that when PAGP patients
start meeting outside of group sessions, it is welcomed as part of
the integration process, as meeting members in ordinary life may
help normalize the extraordinary experiences of the psychedelic
intervention. Some patients were also relieved to realize that dur-
ing the vulnerable psychedelic sessions, boundaries were still
being respected and thus personal freedom was ensured, which
aided the process of opening up to the group on one’s own terms
(Passie and Dürst, 2008).
Summarizing the group cohesiveness effects, among others
discussed above, is a PAGP patients’ testimony:
I was a very lonely and disconnected person before I joined
the group. The psychedelic group experiences helped me to
open up, to be close to others, to express myself, to become
authentic and to build relationships. I realized that other
people also had severe problems and to listen to them and
watch them change from one session to the next was
fascinating, enlightening and encouraging. To talk to the
group about all the bad and painful things that had happened
to me as a child was an extremely helpful and healing
experience. I appreciated the group rules and the clear
structure of the workshops. The preparation evening before
and the sharing and integration the morning after the
experience were very important parts of the treatment. (Oehen
and Gasser, 2022)
Catharsis
Catharsis means intense emotional discharge, and whether nega-
tive and positive, it plays an important role in the group therapeu-
tic process. According to Yalom (2005), catharsis alone does not
relate to positive outcomes; group psychotherapy following a
cathartic experience is essential. It is also intricately related to
cohesiveness: ‘members who express strong feelings toward one
another and work honestly with these feelings will develop close
mutual bonds’ (Yalom, 2005).
As psychedelic intake intensifies affectivity and embodiment
(Preller and Vollenweider, 2018), it may lead to cathartic expres-
sion in clinical settings (Gasser et al., 2015). During IPAP, emo-
tional release is associated with peak experiences and ego
dissolution (Thal et al., 2021) and studies demonstrate these to be
a key mediator of successive psychological changes (Bogenschutz
et al., 2018; Roseman et al., 2019). Herein lies a strange paradox:
though the emotions which arise under the influence of psyche-
delics may seem stronger than ever before, psychedelic intake
also allows patients to withstand previously unbearable emo-
tions. This has been called the ‘helioscope effect’ (Hasler, 2022):
Just as a helioscope allows people to directly observe the sun,
psychedelics allow patients to access and process deep traumatic
memories and overwhelming emotions which were previously
too painful to bear.
Recent comparative research has analysed differences
between acute drug effects between PAGP and IPAP settings
using data from the Swiss limited medical use program (2014–
2018). Results show no significant differences (Schmid et al.,
2021) indicating that cathartic effects are comparable between
the two approaches to psychedelic therapy in Switzerland. To
give space to and encourage cathartic processes, Gasser (2022)
advises that during PAGP, the first 5 h of the acute substance
effect should include little to no interaction with other group
members. As the acute drug effects fade, social interactions are
encouraged so that patients can process their cathartic experi-
ences together.
There is a possibility that the expectation of great catharsis
during psychedelic sessions will lead patients to fear losing con-
trol or reliving traumatic memories in front of others. We there-
fore advise offering the patients a sense of autonomy and control
in this process and letting each person discover their boundaries
within their personal experience in the psychedelic session.
This can be achieved using lower to medium–high doses of
psychedelics, which lowers the risk of being overwhelmed.

Ponomarenko et al. 11
PAGP therapists should also refrain from pushing or forcing
patients into processes for which the patient is not ready.
Research shows that as the therapy progresses, members gain
more control and can guide themselves more directly towards
their questions and problems, as instructed by the therapist
(Passie and Dürst, 2008). In our experience, it is ideal for the
therapeutic process that participants have enough control to vol-
untarily surrender themselves to the experience, as unwillingly
losing control can lead to the so-called ‘bad trips’. Maintaining
some level of control seems to be as important in PAGP as the
profound cathartic effect.
Existential factors
In the process of group psychotherapy, Yalom (2005) emphasizes
that members learn about the following five existential factors:
1. Recognizing that life is at times unfair and unjust.
2. Recognizing that ultimately there is no escape from life’s
pain or from death.
3. Recognizing that no matter how close one gets to other
people, one must still face life alone.
4. Facing the basic issues of one’s life, thus living life more
honestly and being less caught up in trivialities.
5. Learning to take ultimate responsibility for the way one
lives life no matter how much guidance and support one
gets from others.
Many current healthcare providers see great potential in psy-
chedelic therapy to treat existential distress (Niles et al., 2021).
Clinical research suggests that IPAP can help patients with life-
threatening diseases by reducing anxiety, depression, hopeless-
ness and demoralization rapidly, substantially and lastingly
(Agin-Liebes et al., 2020; Ross et al., 2016; Schimmel et al.,
2022). It may also enhance the sense of meaning in life
(Hartogsohn, 2018; Preller et al., 2017).
In PAGP specifically, existential factors were often expressed
in a qualitative analysis of demoralized AIDS patients. Psilocybin
helped the group members go from ‘trauma oriented’ to ‘growth
oriented’ and improve emotional processing and regulation, lead-
ing to self-compassion and an empowering internal sense of
security (Agin-Liebes et al., 2021). Ayahuasca-assisted therapy
in a group retreat helped participants with substance use disor-
ders to not only reduce their use of cocaine and alcohol long
term, but also improve their sense of hopefulness, empowerment
and meaning in life (Thomas et al., 2013). Contemporary existen-
tial psychologists explain these therapeutic effects of psyche-
delics with their ability to reduce death anxiety by forcing
confrontation with mortality, reducing self-focus, shifting meta-
physical beliefs, and increasing the feeling of connectedness and
the meaningfulness of life (Moreton et al., 2020).
However, existential realizations should not only be attributed
to the substance itself. Scharfetter (2008) addresses this issue,
expressing concern about clinicians who create unrealistic expec-
tations of psychedelic therapy. Not all suffering should become
the object of therapeutic ‘elimination’, as that would be based on
the hedonistic illusion of a life free of suffering. Instead, the nor-
mality of suffering should be subject to the therapeutic process.
Suffering-free spiritual bliss is a gift sometimes given within a
psychedelic session, but it cannot be the ultimate life goal. It is
the strength and courage, the development of humility and
acceptance, that make the pain and grief of one’s own life beara-
ble. Having psychedelic sessions in a group context may thus
help to ground people in the realization of personal responsibility
by having the continuous support of multiple discussion partners,
including the therapists, rather than one saviour in the form of a
substance or an idealized, overpowering psychedelic therapist
who promises healing and redemption.
Patient vignette
In the fall of 2021, following previous burn-out and depressive
episodes, 46-year-old Maria (fictious name) sought treatment for
major depression and generalized anxiety. She had already tried
different psychotherapeutic methods and had been in almost con-
tinuous treatment for 25 years, including eye movement desensi-
tization and reprocessing, cognitive behavioural therapy (CBT),
mindfulness-based therapy, psychoanalytic psychotherapy and
hypnosis. Maria had also tried different forms of pharmacother-
apy in conjunction with her different psychotherapies, including
drugs for depression, anxiety and insomnia. During the initial
consultations, traumatic episodes emerged and revealed an
intense emotional neglect in her childhood coupled with maternal
physical violence and verbal abuse between 12 and 15 years of
age. Maria was also bullied in school, and she felt severely
manipulated in her first relationship. She developed a chronic
eating disorder in her youth and was having difficulties holding a
stable intimate relationship, resulting in two divorces. She had
three children from three different partners. Given the panel of
her symptoms, she was diagnosed with Recurrent Depression
(F33.2) and Generalized Anxiety (F41.1). Some symptoms
related to a potential comorbidity with bulimia and C-PTSD were
also noticed but not diagnosed. She started weekly ACT (accept-
ance and commitment therapy) talk therapy and later, after
2 months of therapy, she was recommended for a psychedelic-
assisted psychotherapy group, already active and running in the
therapist’s practice. Maria was psychedelic naive, did not recrea-
tionally consume any substances and was initially sceptical of
joining a group setting. The most important uncertainty revolved
around her fear of having to deal with the impact of other partici-
pants’ negative emotions. After the nature of the group setting
and its benefits were explained, she decided to join group ther-
apy. Maria participated in a total of four MDMA group sessions,
which included between 8 and 10 participants together with three
to four therapists, always in the presence of her main therapist.
Overall, Maria showed a remarkable improvement in her rela-
tionship skills and participation in the group dynamic during
these four sessions.
During the first two group MDMA sessions, Maria showed a
marked anxiety and tension about opening up during the first
exchanges with the other participants, which occurred prior to the
substance intake. When having to talk at the opening and at the
ending of the session, she would keep her discourse superficial,
and she would avoid asking or answering questions to or from
other participants. She expressed a feeling of uniqueness and of
being extremely different from the other participants. Until the
second session, Maria was unable to give feedback during the
common discussion at the end of the session because she felt
emotionally overwhelmed by the group sharing. During the third
and fourth sessions, she increasingly started being more open in

12 Journal of Psychopharmacology 00(0)
her communication and participating in the discussion arising
from participants confronting each other. She was able to speak
more about her own personal story and suffering.
During the fourth session, Maria gave feedback to others mul-
tiple times. She discussed how she had seen them change during
therapy, how their comments helped her reflect on her condition,
how she felt that they all were looking for the same positive feel-
ing of being accepted and cared about, and how being heard by
the group was more crucial than she previously thought. She
could also finally express difficult painful emotions and wept
while sharing her MDMA experience with the group. In particu-
lar, Maria realized she could stand her own emotions and would
not need to avoid or run away from them anymore.
This case shows some of the group factors in action, interact-
ing with each other, from the perspective of one participant. The
interplay between the patient and the group is recognizable by
her increasing participation in the group dynamic. The opening
and deepening of personal processes, though at different rapidity
and intensity for each patient, creates connectedness within the
group. Patients who share their own experiences become increas-
ingly able to learn from each other because they develop a com-
mon language and reference system from one session to the next.
They can use this mutual psychoeducation to understand them-
selves, the other participants and the overall therapeutic process
itself. During the fourth session in particular, Maria’s perspective
shows us an interplay of instillation of hope, altruism, interper-
sonal learning, universality, group cohesiveness and catharsis.
After 10 months, a total of 28 sessions of weekly therapy, and
four MDMA group sessions (125 mg for the first session, then
150 mg for the following three sessions), Maria reports a marked
improvement in various dimensions of her quality of life. At the
time of writing, Maria has been free of bulimic episodes for the
past 4 months. She is relieved of the chronic anxiety she woke up
with every morning for years. She reports an improvement in her
sleep regulation, her relationships with her children and in her
capacity for dealing with stress at work without a major break-
down. Maria also reports having milder depressive symptoms.
Nevertheless, she still suffers from a feeling of shame that is at
the root of her persistent depressive symptoms as well as great
difficulties positively engaging in intimacy with her partner and
parents.
Challenges of PAGP
Institutional challenges
In the emerging field of clinical treatment and research into psy-
chedelic therapy, the individual approach is currently preferred to
PAGP. One can hypothesize many reasons for this, including lack
of knowledge about how to conduct PAGP, as well as the long
tradition of individualistic approaches to psychotherapy in gen-
eral. The implementation of PAGP into the healthcare system at
psychiatric hospitals is also difficult because it requires a great
deal of coordination, attention and specific knowledge about
PAGP that is different from other current practices.
Structural challenges
Some difficulties that PAGP brings may be avoided in the indi-
vidual setting, one of them being the more rigid procedures. In
comparison to the individual approach of IPAP, in which one or
two therapists accompany one patient, our experience showed
that in PAGP there can be up to four therapists who may be guid-
ing a group at a time. The group environment may thus seem
impossible to predict at first. For it to not become laborious or
chaotic, it is important to outline a code of conduct and specific
rules to which every participant must agree. It is therefore essen-
tial to establish a balance between individual and group pro-
cesses, which requires good choices about which patients to
include. Time management and session schedules are less flexi-
ble, and therapists must be mindful of individual needs regarding
stillness, talking and movement, as well as substance-related
openness. However, given a strong group cohesiveness, experi-
enced PAGP members tend to actively maintain boundaries and
group rules in a mostly calm and open manner, which should be
encouraged. Faced with this challenge, Spencer (1963) at first
allowed the patients to freely do as they wish during the psyche-
delic sessions, stating that
Certainly the patients in this group needed to pass through a
phase in which they could do exactly as they wished and still
retain the therapists’ love before they could pass on to a more
mature phase of accepting the demands of society upon them.
During psychedelic sessions, coordinating individual differ-
ences in dose and effect may be laborious, as well as disturbances
due to noise and restlessness. In general, we can say that a higher
degree of illness requires more active guidance of the patient.
However, it also can be especially difficult to integrate distinctly
egocentric individuals within the group. Generally, there is also
the concern of patients being less open in the group setting com-
pared to the individual setting, as they could be worried about
other people’s reactions during the session. This could lead to
interferences or a loss of focus within the intrapersonal process.
Challenges with therapeutic factors
Challenges related to PAGP are similar to those found in conven-
tional group therapy. Before starting therapy, therapists should
carefully screen patients to determine eligibility. External factors,
such as acute stress or moving, can lead to early dropout (Yalom,
1966). It is also important to not create false expectations that the
therapy is beneficial for everyone, as some patients may prefer
individual therapy or request a disproportional amount of person-
alized attention.
A lack of universality can sometimes lead to ‘early provoca-
teurs’ (Yalom, 1966), who exhibit aggressive behaviour and then
leave due to anxiety. Others may develop a feeling of not fitting
in, which is called group deviancy and is accompanied by a lack
of psychological sophistication and interpersonal sensitivity.
This can damage the group cohesion process if not addressed by
the therapist. Providing individual sitters for these patients can
help them feel supported.
Without the corrective recapitulation of the primary family
group, problems with intimacy may arise, such as schizoid with-
drawal, maladaptive self-disclosure or unrealistic demands for
‘instant intimacy’ (Yalom, 1966). When socializing techniques
are not developed with the guidance of the therapist, complica-
tions can also arise through subgrouping, in which patients who
feel left out create their own subgroups within the therapy group,
damaging the group cohesion process.

Ponomarenko et al. 13
Interpersonal learning processes can be disturbed when
patients are strongly affected by hearing the problems of other
group members, causing fear or upset. This can have a lasting
impact on the group atmosphere, and therapists should address
these reactions individually and encourage an accepting mindset
within the group.
Another point addressing the interpersonal exchange in PAGP
is that some authors have argued that psychedelic experiences
can seem ineffable (Nielson et al., 2018; Nielson and Guss, 2018;
Pedersen et al., 2021). They can be vastly different not only inter-
but also intra-individually, potentially creating a greater feeling
of isolation or uniqueness amongst group members rather than
the desired therapeutic outcome. This especially concerns diffi-
culty describing the experience in integration sessions, but also
portends difficulties with properly informing naïve patients about
what they can expect in a psychedelic session (Johnson et al.,
2008). It therefore generates considerations regarding the correct
preparatory approach of set and the establishment of a shared
vocabulary. More research on PAGP is needed to identify the
most beneficial therapeutic context to introduce the psychedelic
group experience to the patient. Focusing more closely on the
influence of an interpersonal setting on psychedelic intake may
shed light on further therapeutic factors.
Depending on numerous variables in patients’ predisposition,
dosage, set and setting, the ‘peak psychedelic experience’, mean-
ing the moment the effects are perceived to be the most intense,
is not always pleasant (Passie and Dürst, 2008). ‘Bad’ or ‘chal-
lenging’ experiences endure critical discussion about their thera-
peutic efficacy, as some argue that they can lead to therapeutic
benefits, and others point out that they can have the potential to
be damaging or provoke undesirable changes in core beliefs
(Carbonaro et al., 2016; Greif and Surkala, 2020; Roseman et al.,
2018b). This may lead the patient to lose hope with the therapy
approach or create disturbances within the group. An essential
aspect of PAGP is that challenging experiences are well sup-
ported as they happen, as well as thoroughly discussed in a social
setting after they subside. Giving psychedelics too frequently
without sufficient integration of the experience into daily life
may also result in delusions and disappointment in the long run
(Oehen, 2013).
Finally, we echo some problems mentioned in an earlier
PAGP study (Spencer, 1963). Treating all patients in the group
equally is important to lessen the feeling of uniqueness and
strengthen the group cohesiveness. Adding to this, not all partici-
pants will always be willing to participate in the group process,
which can affect the therapeutic factors in general. Lastly, thera-
pists need to be prepared for the potential physical acting out of a
cathartic expression.
The PAGP therapist
In PAGP, it is not only the substance that has therapeutic effects,
but also the accompanying psychotherapy, for which correct
training of the therapist plays a crucial part. Phelps (2017)
outlines six basic competencies of the psychedelic therapist:
empathetic abiding presence, trust enhancement, spiritual intel-
ligence, knowledge of the physical and psychological effects of
psychedelics, self-awareness and ethical integrity, and profi-
ciency in basic and complementary psychotherapeutic tech-
niques. As PAGP usually involves multiple therapists, differences
in therapeutic styles should be discussed beforehand to avoid
incoherent processes. Current models of successful PAGP sug-
gest using meaning-centred therapy (Beaussant et al., 2021) or
the Accept, Connect, Embody model, based on ACT (Teixeira
et al., 2022), as well as the theoretical integration of attachment
theory, mindfulness-informed and relational approaches (Agin-
Liebes et al., 2021) and synergistic therapeutic mechanisms (Thal
et al., 2021).
While conventional group psychotherapy often has a specific
focus or goal (Teixeira et al., 2022), in PAGP the focus lies
broadly within the experience of the psychedelic sessions, the
interpretation of its personal insights, and the integration of the
aforementioned psychological processes. The personal issues
that may come up during this therapy may vary a lot within the
group. Therefore, therapists need to be able to flexibly observe
and reframe events to promote the core processes of the group,
while also being able to bring the group’s attention to a particular
issue a given patient is going through. This is possible during the
group integration discussions, in which patients share their own
subjective experience with the group.
Clinicians should also be aware of the intensity and length of
psychedelic sessions. Sufficient time needs to be spent with
every group member to support connectedness, comfort and ther-
apeutic progress. This goal is complex and especially difficult in
a group setting. Therefore, therapist cooperation is advised
(Johnson et al., 2008), preferably involving therapists of different
genders (Passie and Dürst, 2008).
Specific interventions by PAGP therapists are particularly
required in situations where patients show difficulties during
psychedelic sessions, such as being emotionally overwhelmed,
dissociating, freezing or resisting. Verbal interventions should be
kept to a minimum until the late phase of the session since they
risk leading the patient away from the embodied emotional expe-
rience. Alternatives may include humming, singing, storytelling
and reciting poems (Oehen, 2013). In addition, patients with deep
rooted trauma sometimes benefit from emotionally corrective
and restructuring interventions involving body contact and
appropriate touch included in group settings (Oehen, 2013;
Oehen and Gasser, 2022; Spencer, 1963), whereby we do not dif-
ferentiate between different ways of touch in individual and
group settings. After having clearly obtained consent for this
aspect of the therapy during preparation with the patient, the
PAGP therapist may touch the public parts of the patient’s body
during a challenging moment of the experience. Some examples
of this include contact between the hand of the therapist and the
hand, head or shoulder of the patient.
Another responsibility of the psychedelic therapist is to be
mindful of transference in the interactions between therapists and
group members, as well as between the group members.
Transference is a concept derived from psychoanalysis and refers
a tendency for representational aspects of important relation-
ships, such as feelings, desires and expectations of one person, to
be consciously or unconsciously applied to others (Levy and
Scala, 2012). In the group therapy setting, transference can
become more complex, less controllable and potentially rein-
forced by unprofessional behaviour of other group participants,
including unwanted intimacy and sexuality (Peluso et al., 2020).
Therefore, the observance of boundaries and clear and unambig-
uous group rules as well as a transparent therapy concept are
indispensable.

14 Journal of Psychopharmacology 00(0)
The therapists’ self-experience with
psychedelics
In the 18th and 19th centuries, clinicians were encouraged to
have self-experiences with psychoactive substances before
administering them to patients. In contrast to such controlled
self-experiments, today’s scientific experiments that are more
carefully designed often do not provide enough detailed informa-
tion about the subjective experiences (Passie and Brandt, 2018).
However, therapists must understand the psychoactive effects to
know how to convey psychedelic therapy to their patients. If a
therapist expects overly idealistic outcomes from the work with
psychedelic substances, he or she may not only overstrain the
patient, but also abandon the attitude of a supportive psychother-
apist (Noorani and Martell, 2021). In conveying the particular
nature of PAGP, we argue that the therapist can gain the most
accurate knowledge of how to understand and describe the com-
plexity of psychedelic states by experiencing psychedelics them-
selves. In the same way as any psychotherapist has the duty,
ethically and administratively, to have undergone psychotherapy,
we believe that a PAGP therapist would benefit from their own
supervised psychedelic intake in a therapeutic group setting,
which should be part of the obligatory psychotherapeutic training
(Gasser, 2022; Oehen, 2013). As Oehen and Gasser (2022) have
stated, ‘In our view, psychedelic therapists should have experi-
enced drug-induced altered states of consciousness in a therapeu-
tic setting themselves in order to fully appreciate and understand
the mechanisms of action, possibilities, limitations, and pitfalls
of the process’.
Since a great deal of the psychotherapy work revolves around
promoting the patient’s self-reflective and self-regulating skills,
psychedelic therapists will be better able to guide the patient in
discovering and understanding how their mind works if they can
refer to their own subjective experience. This is even more
important when dealing with psychotherapies that used altered
states of consciousness, like IPAP and PAGP. This is also the case
for mindfulness-based CBT, which is based on the patient learn-
ing meditation techniques. The mindfulness therapist in training
is asked to practice mindfulness meditation and learn from per-
sonal experience in order to be able to best implement this ther-
apy and understand patients’ experiences with it (Crane and
Kuyken, 2013). In addition, patients in altered states of con-
sciousness sometimes pick up on extremely subtle cues to the
therapist’s current mental state. A therapist who is not authentic
and aware of his or her own weaknesses and unresolved issues
will not always be able to fool patients, which may get in the way
of the therapeutic process (Oehen, 2013).
However, therapist experiences with psychedelics may not be
currently feasible, since psychedelics are still scheduled as dan-
gerous, illegal drugs under the UN Conventions and many gov-
ernments’ drug laws (Nutt and Carhart-Harris, 2021). Nowadays,
an aspiring psychedelic psychotherapist could feel forced to do
something that is illegal or at least stigmatized, even in countries
with legal psychedelic drugs (Nielson and Guss, 2018). If there is
no access to an organized therapeutic setting, taking psychedelic
substances alone risks either overburdening the therapist or being
perceived as superficial. Guided psychedelic sessions in an ille-
gal context could also create a stigma from the patient perspec-
tive, as they may worry about their therapist engaging in illicit
activities, which could negatively impact trust and the therapeu-
tic alliance (Nielson and Guss, 2018).
There have been only a few documented cases of psychedelic
sessions conducted within a therapist training program. In the
1970s, one study examined 203 mental health professionals
undergoing experiences with LSD as a part of their training in the
United States. However, the data were never systematically ana-
lysed or published (Nielson and Guss, 2018). Individual therapist
experiences have been documented within the MDMA-assisted
therapy training from the Multidisciplinary Association for
Psychedelic Studies, and those therapists reportedly felt more
prepared to conduct their therapy sessions (Nielson and Guss,
2018). Further research into therapist efficacy is needed to evalu-
ate this result. Regarding PAGP, one psychedelic therapist train-
ing at the Imperial College London has successfully piloted a
study on potential psychedelic therapists undergoing a voluntary
group experience with psilocybin (Nutt and Carhart-Harris,
2021). These are first steps towards a wider acceptance of guided
psychedelic sessions in a PAGP therapy training program, but
more research into outcomes from these trainings is needed.
Limitations and future considerations
One limitation of this article is a general lack of clinical studies
on PAGP, despite the fact that this therapeutic framework is
already practiced in some countries. Future research could con-
sider comparing conventional group therapy and IPAP to PAGP
to determine more similarities and differences in method and out-
come. Within clinical research, a greater focus could be placed on
challenges and problems during the PAGP process, as this helps
to improve the method over time. In addition, the standardization
of the psychotherapeutic techniques used in trials with psyche-
delic drugs has been insufficiently studied.
Furthermore, no direct causal relations can be made from neu-
robiological findings to therapeutic outcome; we only use this
information to demonstrate potential connections. Future research
could benefit from studying neurobiological changes following
PAGP, as well as predictors of PAGP treatment response.
Future research on PAGP could also include long-term
assessments of therapeutic effects using both quantitative and
qualitative approaches and comparing PAGP to other forms of
therapy, such as IPAP and conventional group psychotherapy.
Potential selection bias should also be considered when dealing
with participants with prior experience with psychedelics.
Furthermore, the specifics of different PAGP settings and thera-
peutic approaches should be investigated with the aim of creat-
ing internationally recognized guidelines, as well as improving
the cost–benefit ratio of psychotherapeutic treatment.
Conclusion
The aim of this paper was to examine PAGP through the lens of
Yalom’s 11-factor framework for group therapy. We synthesized
existing literature that outlines the potential effectiveness and
challenges of PAGP. We hope that this information provides a
conceptual base for more clinical research on PAGP, as well as its
potential implementation in treatment centres.
In summary, we conclude that psychedelics may enhance
important group therapeutic factors. Psychedelic substances can
broaden the autobiographical perspective, allowing patients to re-
process their personal experiences. They also seem to reduce self-
focus and enhance prosocial behaviour, enabling deeper empathy

Ponomarenko et al. 15
and connection between group members. Psychedelic-assisted
therapeutic sessions also support patients in processing frightening
stimuli in the new social context, and enhanced learning ability may
give them the opportunity to improve their social skills directly with
the support of other group members. Psychedelics can be seen as
social catalysts, amplifying group connectedness. In a well-guided
setting, the intense cathartic effects of these substances are main-
tained even within the group experience. However, PAGP also has
a relatively rigid structure with clear rules. Taken together with its
social context, this may lead individuals to become less open and
experience difficulties during the psychedelic session. The ineffa-
bility of the experiences may also prove challenging, though this
can be overcome by adequate therapeutic training. The art is thus to
maintain a clear, binding structure and orderly flow while being as
open as possible to the experiences of the participants.
In sum, we conclude that psychedelic substances can be pow-
erful vectors of interpersonal psychotherapy, and PAGP has par-
ticular therapeutic potential due to its increased accessibility and
suitability for treating interpersonal issues.
Author contributions
Ponomarenko Polina: writing original draft (lead); writing reviewer
response and editing (lead); creating tables and graphics (lead); Seragnoli
Federico: writing original draft (support); writing case vignette (lead);
writing reviewer response and editing (support); Calder Abigail: revis-
ing content, structure and writing style (support); Oehen Peter: review-
ing original draft (support); Hasler Gregor: conceptualization (lead);
project administration (lead); reviewing original draft (support); writing
reviewer response and editing (support).
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to
the research, authorship and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the
research, authorship, and/or publication of this article: This work was
supported by the University of Fribourg.
ORCID iDs
Federico Seragnoli https://orcid.org/0000-0001-9261-770X
Peter Oehen https://orcid.org/0000-0001-7966-523X
Gregor Hasler https://orcid.org/0000-0002-8311-0138
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