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![The time course of heart-rate variability (HRV) changes are shown in relation to the onset of the 3 different movement types analyzed. Analysis was performed in the time domain (HRV) as well as in the time-frequency plane using a continuous wavelet transform (low frequency [LF], high frequency [HF], and LF/HF). Thick lines show mean ± SEM values. Stair plots below each graph indicate the statistical probability that HRV changes are equal for all 3 movement types at the given time point. Note the 2 distinctive peaks of LF and HF power changes as well as of LF/HF ratio changes, occurring similarly for all examined movement types. LF-power-and LF/HF-ratio changes before and immediately after movement onset (indicating sympathetic activations, process 2) were significantly different between movement types. Furthermore, LF-power changes 4 seconds after movements (indicating vagal activations, process 3) were significantly different. PLMS refers to periodic limb movements of sleep; ILMS, isolated leg movements in sleep; RRLMS, respiratory-related leg movements in sleep.](profile/Adrian-Guggisberg/publication/6255863/figure/fig3/AS:394694036082707@1471113799551/The-time-course-of-heart-rate-variability-HRV-changes-are-shown-in-relation-to-the.png)
The time course of heart-rate variability (HRV) changes are shown in relation to the onset of the 3 different movement types analyzed. Analysis was performed in the time domain (HRV) as well as in the time-frequency plane using a continuous wavelet transform (low frequency [LF], high frequency [HF], and LF/HF). Thick lines show mean ± SEM values. Stair plots below each graph indicate the statistical probability that HRV changes are equal for all 3 movement types at the given time point. Note the 2 distinctive peaks of LF and HF power changes as well as of LF/HF ratio changes, occurring similarly for all examined movement types. LF-power-and LF/HF-ratio changes before and immediately after movement onset (indicating sympathetic activations, process 2) were significantly different between movement types. Furthermore, LF-power changes 4 seconds after movements (indicating vagal activations, process 3) were significantly different. PLMS refers to periodic limb movements of sleep; ILMS, isolated leg movements in sleep; RRLMS, respiratory-related leg movements in sleep.
Source publication
Periodic leg movements in sleep (PLMS) are frequently accompanied by arousals and autonomic activation, but the pathophysiologic significance of these manifestations is unclear.
Changes in heart rate variability (HRV), HRV spectra, and electroencephalogram (EEG) spectra associated with idiopathic PLMS were compared with changes associated with isol...
Contexts in source publication
Context 1
... whereas the power increase associated with PLMS showed a gradual progression from low to high EEG frequencies, it occurred suddenly and simultaneously over almost the entire frequency range for ILMS and RRLMS. Figure 3 displays a comparison of HRV and LF/HF power changes between the 3 different types of leg movement in sleep. The deceleration of HRV was significantly larger after the onset of PLMS than after RRLMS and tended to be larger after PLMS than after ILMS. ...
Context 2
... 2 represents a sympathetic activation, since the HRV transiently increases ( Figure 1A) and the wavelet transform discloses a strong increase in LF power ( Figure 1B, process 2) and the LF/HF ratio (Figure 3). [HF], and LF/HF). ...
Context 3
... This is of importance in case of RRLMS, in which apneas and hypopneas may lead to biased HF power changes. However, since HF power changes of RRLMS were similar to those of ILMS (Figure 3), in which no apneas occurred, the influence of respiration is probably negligible in our setting. ...
Context 4
... comparing the HRV associated with different types of leg movements in sleep, we found significantly greater sympa- thetic activation for PLMS than for the other leg-movement types (Figure 3, LF and LF/HF changes). This finding is in accordance with a recent study reporting that sleep periods with PLMS are associated with significantly greater sympathetic activation than are sleep periods without PLMS of the same subject suffering from RLS. 15 Thus, sympathetic activity appears to be functionally related with PLMS. a A comparison of EEG changes between different movement types further revealed that, whereas gamma rhythms as markers of cortical arousal and cortical movement preparation started to increase before the onset of ILMS and RRLMS, they only started after onset of PLMS (Figure 4, sixth graph). ...
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Background
Recurrent intermittent hypoxia and subsequent increased sympathetic nervous system activity have been adopted as possible mechanisms underlying cardiac rhythm disturbances in obstructive sleep apnea syndrome (OSAS).Methods
We analyzed nocturnal heart rate variability (HRV) in 80 patients (74 males, 6 females, mean age 47.01 ± 10 yrs) wit...
Citations
... These changes in the ventricle and atria may activate the stretch-mediated ion channels and cause cardiac remodeling, hence enhancing the tendency to arrhythmia. These episodes of obstructive apnea lead to corrected QT interval prolongation and progressive increases in atrial premature beat frequency, which have been known as precursors to AF [74,75]. ...
Atrial fibrillation (AF) is a prevalent cardiac arrhythmia that still remains a significant health concern, especially due to its consequences, including stroke and heart failure. This review explores the intricate interplay between AF, lifestyle choices, and dietary habits. It is particularly focused on findings from diverse studies about non-pharmacological methods of managing AF. Moreover, its purpose is to elucidate the implementation of lifestyle changes such as physical activity or proper diet choices in the integrated treatment strategy of patients with AF.
... Other data has suggested that perhaps the HRV and electroencephalogram changes associated with limb movements are not specific to PLMS, but in fact occur during all types of leg movement [14]. One study tried to answer this question by examining not only PLMS but also isolated leg movements during sleep, and found that HRV and EEG changes occur uniformly before and during all leg movements; however, the intensity of HRV was statistically greater in PLMS compared to isolated leg movements, suggesting sympathetic activity as the physiological process was most probably causally related to PLMS [14]. ...
... Other data has suggested that perhaps the HRV and electroencephalogram changes associated with limb movements are not specific to PLMS, but in fact occur during all types of leg movement [14]. One study tried to answer this question by examining not only PLMS but also isolated leg movements during sleep, and found that HRV and EEG changes occur uniformly before and during all leg movements; however, the intensity of HRV was statistically greater in PLMS compared to isolated leg movements, suggesting sympathetic activity as the physiological process was most probably causally related to PLMS [14]. Other analyses have examined HRV and HRV HF compared to sleep with PLMS and sleep without PLMS, and have found elevation of the HRV HF tens of seconds prior to the PLMS series versus elevation at times of sleep without [15]. ...
... To the best of our knowledge, this is the first study examining basal HRV in a large number of subjects in both wake and NREM sleep across groups of subjects with RLS, PLMS, and the combination of RLS and PLMS, as compared to non-RLS/PLMS subjects during overnight polysomnography. Prior studies utilizing HRV analysis have focused on periods with leg movements in NREM sleep, given the fact that movement-related surges of sympathetic activity that are known to occur 20,21 ; however, only a limited number of studies have investigated basal autonomic regulation in PLMS 8,22 . Our study revealed that the PLMS group had reduced basal sympathetic activity in wakefulness, but basal sympathetic predominance during NREM sleep, when compared to the non-RLS/PLMS group; these findings distinguished the PLMS group from both the RLS and the RLS/PLMS groups. ...
Introduction: The relationship between the autonomic nervous system
and restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) consists of
varied and somewhat conflicting reports. In order to further elucidate these complexities,
a retrospective analysis of polysomnography (PSG) records and clinical data was performed.
Methods: Records from 233 adult subjects were randomly selected and organized into one of
four groups ("non-RLS/PLMS" [n=61], "RLS" [n=60], "PLMS" [n=58], and "RLS/PLMS" [n=54]).
Heart rate variability (HRV) analysis was based on 5-minute samples of 2-lead
electrocardiogram data isolated from PSG recordings during wakefulness and NREM sleep, and
included mean RR interval (labeled "NN") and standard deviation of the RR intervals
(labeled "SDNN"), and HRV power, very low frequency (VLF), low frequency (LF), and high
frequency (HF) spectral bands. Results: A significant reduction in the VLF band in the PLMS
group as compared to the non-RLS/PLMS group (542±674 vs. 969±1025
ms2, p=0.038) was found in wakefulness. Statistically
significant differences were seen in the PLMS group as compared to the non-RLS/PLMS group
with a reduction in SDNN (p=0.001) and the HF (p=0.001)
band, and an increase in HRV power (p=0.001), and the VLF
(p=0.005) and LF (p=0.001) bands in NREM sleep.
Conclusions: The PLMS group exhibited reduced basal sympathetic activity in wakefulness,
but basal sympathetic predominance during NREM sleep, distinguishing this group from the
RLS and RLS/PLMS groups.
... This finding is also supported by previous studies showing that the number of PLMS did not sufficiently decrease after CPAP implementation in patients with SDB and PLMS [49][50][51]. Sympathetic overactivity, apart from being present in sleep-disordered patients, has also been linked to the generation of PLMs [52]. Based on these findings, it could be inferred that the presence of SDB leads to a sympathetic overactivity, which in turn generates "genuine" PLMS, creating a vicious circle. ...
Background:
Periodic Limb Movements during Sleep (PLMS) have been described to be frequently present in stroke patients. We aimed to evaluate the prevalence and severity of PLMS in acute stroke patients and clarify the association between PLMS and coexisting Sleep Disordered Breathing (SDB). Additionally, we focused on identifying variables that could independently predict the presence of PLMS in patients with acute stroke. The potential impact of PLMS on stroke outcome at three months was investigated as well.
Methods:
In this study, we performed overnight polysomnography on consecutive stroke patients within 72 h from symptom onset. Data regarding clinical and imaging characteristics were prospectively collected. National Institute of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS) and Epworth-Sleepiness Scale (ESS) were used to evaluate stroke severity on admission, stroke outcome at three months and history of daytime sleepiness, respectively. We documented PLMS and SDB using standard polysomnography criteria.
Results:
We prospectively assessed 126 patients with acute stroke [109 with ischemic and 17 with hemorrhagic stroke, mean age 60 ± 11 years, 68% men, median NIHSS score on admission: 3 (IQR: 2-7)]. The overall rate of PLMS in our cohort was 76%, and the rate of SDB among patients with PLMS was 83%. PLMS detection rates differed significantly (p-value: <0.001) according to SDB, with PLMS prevalence increasing with greater SDB severity. SDB could independently (OR:4.869, 95% CI: 1.884-12.784, p-value: 0.001) predict the presence of PLMS in the acute stroke phase in multivariable analyses adjusting for potential confounders. Moreover, baseline stroke severity (NIHSS-score increase in per-1 point: OR: 0.819, 95% CI: 0.737-0.895, p-value < 0.001) and PLMS (OR:0.099, 95% CI: 0.009-0.482, p-value = 0.015) were significantly associated with the likelihood of excellent functional outcome (mRS-scores: 0-1) at 3 months.
Conclusion:
The common presence of mostly severe PLMS in patients with acute stroke and their negative effect on stroke outcomes point out the necessity for early PLMS detection and treatment.
... PLMS are strongly associated with increased sympathetic activity. However, there is some debate whether PLMS-triggered arousals lead to sympathetic surges, or if the hyperexcitable sympathetic state precedes PLMS (Guggisberg et al., 2007;Ware et al., 1988). Nevertheless, increased sympathetic activity leads to rises in blood pressure (Hart, 2016), vascular inflammation (Hart, 2016), hypercoagulation (Bikov et al., 2021) and dyslipidaemia (Lambert et al., 2013), all being hallmarks of atherosclerotic processes. ...
... Periodic limb movements may elevate cardiovascular risk through surges in sympathetic system activity (Guggisberg et al., 2007;Ware et al., 1988). Indeed, physiological studies showed increases in muscle sympathetic nerve activity (MSNA) during PLMS. ...
Periodic limb movements during sleep and obstructive sleep apnea are both associated with increased sympathetic tone, and have been proposed as risk factors for heart diseases and, in particular, cardiovascular disease. As sympathetic system activation may lead to dyslipidaemia, periodic limb movements during sleep could be an additional risk factor for cardiovascular disease in patients with obstructive sleep apnea. The aim of the study was to determine whether the presence of periodic limb movements during sleep affects serum lipid levels in obstructive sleep apnea. Total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, non- high-density lipoprotein cholesterol and triglyceride levels were investigated in 4138 patients with obstructive sleep apnea in the European Sleep Apnea Database (ESADA) cohort, divided into those with periodic limb movements during sleep index ≥ 15 per hr (n = 628) and controls (n = 3510). ANCOVA adjusted for age, sex, body mass index, apnea-hypopnea index, alcohol intake, smoking status, diabetes, insomnia and study site was used to assess differences in lipids between periodic limb movements during sleep and controls. Patients with periodic limb movements during sleep (24% female, 54.4 ± 12.1 years, body mass index 31.9 ± 5.8 kg m-2 , apnea-hypopnea index 36.7 ± 25.4 per hr) had higher triglyceride (1.81 ± 1.04 versus 1.69 ± 0.90 mmol L-1 , p = 0.002) and lower high-density lipoprotein cholesterol (1.19 ± 0.34 versus 1.24 ± 0.37 mmol L-1 , p = 0.002) levels, whilst there was no difference in either total cholesterol (4.98 ± 1.10 versus 4.94 ± 1.07 mmol L-1 ), low-density lipoprotein cholesterol (3.04 ± 0.96 versus 2.98 ± 0.98 mmol L-1 ) or non- high-density lipoprotein cholesterol (3.78 ± 1.10 versus 3.70 ± 1.05 mmol L-1 ) concentrations (all p > 0.05). The results remained unchanged after most sensitivity analyses. Patients with obstructive sleep apnea with periodic limb movements during sleep had more prevalent cardiovascular disease (11% versus 6%, p < 0.01). Periodic limb movements during sleep in obstructive sleep apnea is associated with dyslipidaemia independently of important confounders. Our results highlight periodic limb movements during sleep as an additional risk factor for cardiovascular disease in obstructive sleep apnea.
... Data from the literature indicates that HRV decreases in PLMS with a concomitant increase in sympathetic tone [29][30][31]. Some studies additionally have indicated decreased vagal activity [32]. ...
... It has been reported that as much as 99% of PLMS is associated with changes in HR [39]. Increases in HR and BP are associated with increased sympathetic arousal, sometimes in combination with arousal in EEG, shortly before the onset of periodic limb movement [30,40]. In our study however, PLMS with arousals were excluded, which could explain the lack of changes in HR and BP. ...
Introduction. The phenomenon known as periodic limb movements in sleep (PLMS) has been linked to a change in autonomic nervous system (ANS) activity and its effect on circulatory regulation. Autonomic dysfunction or dysregulation in patients with PLMS has been described in some domains; however, any relationship between heart rate variability (HRV) and PLMS has not been clearly established. HRV analysis is a recognised, non-invasive research method that describes the influence of the ANS on heart rate (HR). The aim of our study was to further investigate the dysregulation of autonomic HR control in patients with PLMS.
Material and methods. We undertook a retrospective analysis of the polysomnographic (PSG), demographic and medical data of five patients with a total number of 1,348 PLMS. We analysed HR, HRV HF, systolic blood pressure (SBP), and diastolic blood pressure (DBP) for 10 heartbeats before the series of PLMS and 10 consecutive heartbeats as beat-to-beat measurements. The presented method of using successive, short, 10 RR interval segments refers to the time-frequency measurement, which is very clear and useful for presenting changes in the calculated parameters over time and thereby illustrating their dynamics. This
method allowed us to assess dynamic changes in HRV HF during successive PLMS series. Statistical analysis was performed using IBM SPSS Statistics (v. 28.0.0.0). The Kruskal–Wallis test was performed to find statistically significant changes from baseline.
Results. No statistically significant changes in HR, SBP, or DBP were found in our group, although an increase in the value of the HRV HF was noted, suggesting an increase in intracardiac parasympathetic activity during the subsequent series of PLMS.
Conclusions. Our study indicates an increase in parasympathetic activity during the appearance of successive PLMS, which, with the simultaneous lack of changes in HR, may suggest an increase in sympathetic activity, and therefore the appearance of so-called ‘autonomic co-activation’ resulting in the possibility of life-threatening cardiac events.
Clinical implications. Our findings add to the literature information regarding HRV in PLMS, and highlight the need for further studies to elucidate the effects of these conditions on the ANS, and on cardiovascular health.
... PLMS are strongly associated with increased sympathetic activity. However, there is some debate whether PLMS-triggered arousals lead to sympathetic surges, or if the hyperexcitable sympathetic state precedes PLMS (Guggisberg et al., 2007;Ware et al., 1988). Nevertheless, increased sympathetic activity leads to rises in blood pressure (Hart, 2016), vascular inflammation (Hart, 2016), hypercoagulation (Bikov et al., 2021) and dyslipidaemia (Lambert et al., 2013), all being hallmarks of atherosclerotic processes. ...
... Periodic limb movements may elevate cardiovascular risk through surges in sympathetic system activity (Guggisberg et al., 2007;Ware et al., 1988). Indeed, physiological studies showed increases in muscle sympathetic nerve activity (MSNA) during PLMS. ...
... En el presente estudio analizamos el índice de movimientos periódicos durante el sueño y si estos modifican la presión arterial y variables asociadas durante las 24 horas, como así también la frecuencia cardíaca, en una población pequeña, sin comorbilidades. La pérdida del dipping de la presión arterial nocturna, es indicador de mortalidad cardiovascular (13) , de enfermedad coronaria (14) y de accidente cerebrovascular (15,16) , insuficiencia cardíaca y Cheyne Stokes (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33) , trasplante de corazón (18). La fragmentación del sueño, la baja eficiencia del sueño, insomnio, incluso depresión y ansiedad, más aún asociado a desregulación metabólica como diabetes, obesidad y dislipidemia, se han asociado con hiperactividad simpática y por lo tanto a aumento de la presión arterial y SPI (17) . ...
... Tampoco encontramos diferencias significativas en lo que respecta a Presión de Pulso y Frecuencia cardíaca. Se ha propuesto que los microdespertares autonómicos, por hiperactivación simpática coincidiendo con los PLMS (corroborado por varios autores (24,25) , tanto en sueño NREM como REM (26) siendo el sistema nervioso simpático, el principal asociado (27)(28)(29) . Otros estudios, también analizaron los cambios en la Frecuencia Cardíaca (FC), con análisis espectrales del Electroencefalograma (EEG) (30) , aún en ausencia de despertares visibles a nivel del EEG. ...
Los Movimientos Periódicos de las Piernas durante el Sueño (PLMS), diagnosticados por polisomnografía, se caracterizan por movimientos estereotipados de las piernas que aparecen de forma repetitiva durante la noche. Cada PLMS se asocia a un microdespertar e incrementos de la frecuencia cardiaca, presión arterial y actividad simpática. Objetivos: Analizar asociación entre el índice patológico de PLMS y la PA de 24 horas, en pacientes normotensos. Evaluar la asociación entre índice patológico de PLMS, con alteraciones en la velocidad de onda de pulso y frecuencia cardíaca. Métodos Estudio observacional de casos y controles. Se estudiaron 19 sujetos normotensos mediante Polisomnografía Nocturna y Monitoreo Ambulatorio de la Presión Arterial. Se determinaron las variables: Edad, sexo, peso, índice de masa corporal. La presión arterial y frecuencia cardíaca de 24 hs, diurna y nocturna se evaluaron con monitoreo ambulatorio de presión arterial de 24 h. Se excluyeron pacientes con índice de apneas/hipopneas ≥ 5 e/h. Se describieron las variables y compararon sujetos con y sin PLMS, considerando significativo una p<0,05, además análisis de correlación. Resultados Se estudiaron a 11 pacientes con PLMS patológico y 7 controles (Índice PLMS 35,6±15 versus 7,9±5 respectivamente). Los pacientes con PLMS fueron más jóvenes 57 ±14 versus 64±6; p=0,284 años. La presión arterial de 24 h, fue menor en el grupo PLMS que en los controles (sistólica 114,2±11 versus 123±11; p=0,095; y diastólica 65,7±5 versus 74,4±11, p=0,027). Conclusión Encontramos una relación estadísticamente significativa, inversa, no esperada, al correlacionar los movimientos periódicos de piernas durante el sueño, de grado patológico, con la presión arterial sistólica y media de 24 h, la presión arterial sistólica diurna y nocturna, y la presión arterial media nocturna, como así también hallazgos similares en la presión de pulso de 24 horas y la presión de pulso diurna y nocturna que fueron inferiores al grupo control. No encontramos cambios en la frecuencia cardíaca.
... In RLS patients, an association between PLMS and an increase in both systolic and diastolic blood pressure has been reported (Pennestri et al., 2007;Siddiqui et al., 2007), and changes in blood pressure and heart rate in association with PLMS have been found also in healthy subjects (Pennestri et al., 2013). In line with these findings, activation of the sympathetic nervous system has been found in relation to PLMS (Guggisberg et al., 2007;Lin et al., 2020). Of note, PLM-related increases in heart rate (Winkelman, 1999) seem to be gender and age dependent, with a reduction in heart rate variability with age (Gosselin et al., 2003). ...
Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.
... The presence of sleep-disordered breathing, highly prevalent in the study population (Chen et al., 2015), can have a confounding effect on HRV analysis both because it actually alters autonomic control and because abnormal breathing patterns distort the interpretation of the power spectrum (Tobaldini et al., 2013). The same would be true of leg movements during sleep, which are linked to autonomic activation as well as a potential source of motion artifacts (Guggisberg et al., 2007;Tobaldini et al., 2013). Moreover, despite the fact that the stationarity requirements of spectral analysis warrant the averaging of values from 5-min windows over the entire 12-h period, such averaging obscures detailed information on autonomic modulation (Malik et al., 1996). ...
Background
Despite the emerging clinical relevance of heart rate variability (HRV) as a potential biomarker of cognitive decline and as a candidate target for intervention, there is a dearth of research on the prospective relationship between HRV and cognitive change. In particular, no study has addressed this issue in subjects with a diagnosis of cognitive status including cognitive impairment.
Objective
To investigate HRV as a predictor of cognitive decline in subjects with normal cognition (NC) or Mild Cognitive Impairment (MCI). Specifically, we tested the literature-based hypothesis that the HRV response to different physical challenges would predict decline in different cognitive domains.
Methods
This longitudinal study represents the approximately 3-year follow-up of a previous cross-sectional study enrolling 80 older outpatients (aged ≥ 65). At baseline, power spectral analysis of HRV was performed on five-minute electrocardiographic recordings at rest and during a sympathetic (active standing) and a parasympathetic (paced breathing) challenge. We focused on normalized HRV measures [normalized low frequency power (LFn) and the low frequency to high frequency power ratio (LF/HF)] and on their dynamic response from rest to challenge (Δ HRV). Extensive neuropsychological testing was used to diagnose cognitive status at baseline and to evaluate cognitive change over the follow-up via annualized changes in cognitive Z-scores. The association between Δ HRV and cognitive change was explored by means of linear regression, unadjusted and adjusted for potential confounders.
Results
In subjects diagnosed with MCI at baseline a greater response to a sympathetic challenge predicted a greater decline in episodic memory [adjusted model: Δ LFn, standardized regression coefficient (β) = −0.528, p = 0.019; Δ LF/HF, β = −0.643, p = 0.001] whereas a greater response to a parasympathetic challenge predicted a lesser decline in executive functioning (adjusted model: Δ LFn, β = −0.716, p < 0.001; Δ LF/HF, β = −0.935, p < 0.001).
Conclusion
Our findings provide novel insight into the link between HRV and cognition in MCI. They contribute to a better understanding of the heart-brain connection, but will require replication in larger cohorts.
