Folie à Deux in Monozygotic Twins with Cerebral Palsy

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CLINICAL SCHIZOPHRENIA & RELATED PSYCHOSES
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DOI: 10.3371/CSRP.FRBA.050614
© 2014 Walsh Medical Media LLC
Folie à deux in monozygotic twins with cerebral palsy.
Dimitry Francois, M.D., Evan Bander, Mark D’Agostino, M.D., Alec Swinburne, Lauren
Broderick, Michael B. Grody, M.D., Annaheta Salajegheh, M.D.
Weill Cornell Medical College – Psychiatry, New York, New York
Correspondence:
Dimitry Francois
21 Bloomingdale Road. White Plains. NY. 10605
Fax: 914 997 5770
Tel: 914 997 5770
Email: dif9013@med.cornell.edu

Introduction
Folie à deux or shared psychotic disorder was first described by Lasègue and Falret in
1877 (1) as a “mental contagion” such that delusional ideas from one person were
transferred to at least one other person closely associated with the primary affected
person. Folie à deux is an uncommon condition which has long attracted clinical
attention. Here we describe the first report of folie à deux in monozygotic twins with
cerebral palsy who presented with a shared somatic delusion that they strongly smelled
of feces.
Case Summary
Sister 1 and Sister 2 were born in 1980 as monozygotic twins. Per maternal history and
medical record review the patients were identified as monoamnionic in their mother’s
womb, born 10 weeks premature, required NICU hospitalization, and were subsequently
diagnosed with mild cerebral palsy. Their mother, father, and two brothers had no
history of psychotic illness; there is a paternal aunt with bipolar disorder. Sister 2
underwent multiple orthopedic surgeries for complications of cerebral palsy (CP),
leaving her with a profound limp. However, both twins have persistent, subtle right lower
extremity weakness as a result of CP, but no apparent cognitive deficits. Per mother,
both sisters were "bullied" through school but Sister 1 always tried to "protect" Sister 2.
Both twins finished high school and college without special education, and worked in
administrative positions. Neither had any prior evidence of psychiatric illness, neither
married nor had children, and after moving from their parent's home were domiciled

together in an apartment. There is no evidence or history of substance abuse in either
twin.
In 2011, without a clear precipitating event, Sister 1 began to believe that she was
unable to control the passing of flatus. She also experienced auditory hallucinations of a
voice telling her ‘leave, leave’. Her sister and co-workers reportedly did not notice any
changes in her odor, but due to the insistent nature of her complaints, asked her to seek
medical attention. She did seek medical attention, and over the course of the following
two years she: changed her diet in various ways, tried pelvic floor physical therapy, and
eventually sought surgical treatment. She had two surgeries, a posterior colporrhaphy in
October 2012 and a colon resection in February 2013. Her delusions persisted and
intensified, and at the end of May 2013 Sister 1 sought evaluation for depression on her
own. She was seen in a two-part evaluation because of her bizarre symptom cluster
and concern for psychosis. However, further research into her medical complaints
revealed that they were at least in part based in reality; she had gastrointestinal motility
studies which demonstrated paradoxical puborectalis contraction, a problem with
defecation which could be due, in part, to the CP. She was accepted to the clinic for
treatment of anxiety, was not found to be depressed and was found to have moderate
anxiety. We mainly accepted her for further evaluation and to ensure that she minimized
medical harm to herself with further surgeries as we were concerned that her delusions
might trigger unnecessary surgical procedures. She was prescribed lorazepam initially
for the anxiety and mirtazapine later for insomnia, as well as for self-reported
depression in light of gastrointestinal problems. She never took either medication,

claiming that her psychiatrist was lying to her because she told her that she didn't smell
anything when she was in her office on several occasions. Sister 2, who lived with her
sister in 2011 when the symptoms began, initially did not adopt her complaints or note
any odor. During this time they worked on opposite schedules (day and night shifts
respectively), and had minimal daily contact. However, in December 2012 after Sister 1
stopped working in order to "protect" people at work from her odor, Sister 2 began to
have similar delusions. Sister 2 the more “submissive” twin per the patient’s mother,
quickly reported auditory hallucinations, hearing "leave, leave, leave" periodically
emanating from heating vents in the ceiling. Sister 2 stopped working within a few
months. They reported frequenting emergency departments to seek “cures” for their
odors, and spent days isolated in a park in order to spare others from their fecal odor.
Without income, they were eventually evicted from their apartment and domiciled in a
shelter. For both Sister 1 and Sister 2 there were no reports of any hostile or aggressive
behavior, neurovegetative depressive symptoms, or evidence of mania preceding
hospitalization. They were brought into the psychiatric emergency department by their
father for further evaluation.
Both twins were admitted to a psychiatric hospital, diagnosed with schizophrenia and
placed on different units so as not to potentiate symbiotic pathological behavior (see
discussion for more details). During the initial two weeks of their hospitalization both
twins were started on Risperidone. Despite separation, both continued to manifest
similar somatic and persecutory delusions, as well as ideas of reference. Of note, Sister
1 was noted to become irritated and agitated following telephonic conversations with her

sister. As a result, her treating psychiatrists recommended a complete cessation of
contact. After two weeks on Risperidone titrated up to 6 mg orally daily, Sister 2 noted a
decreased frequency of auditory hallucinations. However her somatic delusions
remained firmly fixed and she continued to isolate: sitting by the windows, avoiding
eating meals in common areas and not attending groups without active coaxing due to a
stated intent of minimizing others exposure to her "odor". MRI obtained showed white
matter changes consistent with CP that were unchanged from prior imaging, and no
evidence of temporal lobe seizures or pathology. She was cross-tapered to Olanzapine,
and the dose was titrated up to 15 mg orally daily over the next two weeks. Concurrent
with the titration she had no contact with her sister. Within these two weeks her auditory
hallucinations ceased, her affect brightened, and her delusions, while still present, were
far less fixed. She was discharged to a partial hospital program, and endorsed a
willingness to return to work.
Sister 1, who as above was more dominant in the relationship, had less difficulty
socializing, and was able to attend most groups despite initially insisting that she was
malodorous and that other patients were talking badly about her. Despite disagreeing
with the treatment team she remained pleasant and in good behavioral control.
Risperdal was titrated up to 6 mg orally daily with good effect, with no cross-taper
required. Weeks ahead of her sister, Sister 1 had a cessation of auditory hallucinations,
demonstrated insight into her delusional thoughts, and endorsed improved mood. She
was discharged to the shelter and her outpatient therapists, also with an intent to return
to work.

Discussion:
Dewhurst and Todd (2) proposed the following criteria when diagnosing folie à deux:
1. Intimate association between partners in the delusion
2. Identical delusional content between partners
3. Partners share, support, and accept both their own delusion and that of their
counterpart.
In this dynamic of transference, the dominant/principle initiates the delusion and the
submissive/ associate acquires the delusion secondarily. According to Soni & Rockley
(3), most cases of folie a deux occur in pairs with social isolation. Additionally, the
principle often has clinical features consistent with paranoid schizophrenia, while the
associate presents with socio-clinical personality vulnerabilities including
“seclusiveness, suggestibility, or dependence on the principle.” Such personality
vulnerabilities can be of a “prepsychotic” pathology, including “suspicious, histrionic,
dependent, or antisocial traits” (4). Specifically, Soni & Rockley (3) postulate that the
associate tends to rationalize and identify with the principle to reduce their own anxiety.
As such, both ego defense mechanisms and inherent personality traits appear to
underlie an associate’s vulnerability to folie à deux. Additionally, there appears to be
evidence for a biological correlate for folie à deux. Folie a deux appears to be more
common in genetically related individuals (5). In the case of identical twins, there
appears to be a powerful link between genetics, complex psychodynamic relationships,
and shared environmental forces that could promote the acquisition of folie a deux (6).
Specifically, there appears to be a “genotype-environment correlation” such that “any

delusional thinking in one twin would tend to be reinforced by the other” (7). Given this
dynamic positive feedback loop, the psychological similarity, parallel life experiences
and unique interpersonal experiences combined with the shared genetic loading, folie à
deux in monozygotic twins creates a unique interplay of both nature and nurture in the
presentation of shared psychosis (6). The primary and recipient/induced individuals in
folie a deux often demonstrate close emotional associations. In this case, the two
patients were identical twins, whose close relationship was further entrenched due to
their shared medical diagnosis of cerebral palsy, their social isolation, cohabitation in a
shelter, and the emotional stress of being bullied from a young age due to their physical
disabilities. Perhaps unsurprisingly, the primary sister was considered the “stronger”,
more dominant sister. From a young age, the primary sister required fewer surgeries
after their premature birth and was characterized by their mother as the protector of the
induced sister. This relationship dynamic likely established a psychological framework
ripe for the development of the shared delusion in the induced sister (4).
Gralnick (5), in reviewing a number of cases of folie à deux, was able to separate folie à
deux into four subtypes: folie imposée (the dominant person with delusions imposes his
or her delusions on a younger, more submissive person), folie simultanée (the
simultaneous appearance of an identical psychosis occurs in two intimately associated
and morbidly predisposed individuals), folie communiquée(the recipient develops
psychosis after a long period of resistance and maintains the symptoms even after
separation), and folie induite(new delusions are adopted by an individual with psychosis
who is under the influence of another individual with psychosis). The folie communiquée

subtype best characterizes these two sisters, since the induced patient was initially
skeptical of the primary’s delusion, but once adopted, the delusion proved difficult to
extinguish. Folie à deux in identical twins has been identified as particularly treatment
resistant (8). In this case we believe the treatment was successful (at least until before
the patients were discharged) due to the proper recognition of the condition and
situation, the fact the sisters were treated by physical separation into different units of
the hospital and the use of an atypical antipsychotic for both patients. Risperidone was
chosen because the option for intramuscular administration was ideal for the medication
naive and potentially noncompliant sisters. The primary sister’s delusions resolved more
rapidly than the induced patient, who continued to perseverate on the delusion despite
frequent reality testing.
The problem of chronic organic brain dysfunction and its etiological role in various
psychiatric diagnoses, whether presenting classically or in an atypical manner, has
been a point of much discussion and controversy. Rutter (9) in his report to the Third
W.H.O. Seminar on Psychiatric Diagnosis pointed out that the diagnosis of Cerebral
Palsy does not leave room for differentiation “between a child with cerebral palsy, but no
psychiatric problems, and a child with cerebral palsy who also showed a psychosis or
neurosis.” There are few descriptions of presentation of acute psychosis in this
population, and this is the first report that we know of regarding a shared psychotic
disorder involving two individuals with CP. Some descriptions (10, 11) describe acute
onset, florid and fluctuating symptoms successfully treated with antipsychotics. If the
nonprogressive brain lesions that characterize Cerebral Palsy play an etiological role in

various complex psychiatric presentations, such as the folie à deux in this case, the
question beckons -by what underlying, and perhaps characteristic, mechanisms.
Considerations could include the lesions itself, the associated intellectual impairment
and effect on sensorimotor and speech/language functioning, environmental protective
and risk factors, and psychosocial defensive and adaptive styles which may be more
prone to psychotic-level manifestations. The successful management with neuroleptics
in this and other cases seems to point to a standard that would not deviate from
treatment of such symptoms in populations without evidence of early developmental
nonprogressing brain dysfunction. Reviewing the literature, Shiwach and Sobin found
that delusional disorder is the most common primary diagnosis in folie à deux of twin-
pairs, as compared to schizophrenia in non-twin pairs. Psychosis secondary to the
general medical condition of cerebral palsy must also be considered in the sisters.
However, based on EEG and MRI, the contribution of cerebral palsy was less likely one
of biology as opposed to psychosocial priming of parallel life experiences and emotional
identification.
Conclusion:
Folie à Deux is a rare phenomenon. This example of shared psychotic disorder in
monozygotic twins with cerebral palsy is a good illustration of the interactions between
common genetic make-up, common and individual environmental agents and the nature
of relationship between the inducer and the induced. Our case suggests that treatment
with risperidone can lead to a good clinical outcome with a remission of the psychotic
symptoms.

Acknowledgments
The authors report no conflict of interest.
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