Dream Enactment Behavior Research Articles

Prodromal markers of α-synucleinopathy neurodegeneration in 'isolated' recurrent dream enactment behaviors among first degree relatives of patients with REM sleep behavior disorder - preliminary validation of prodromal rbd concept

Prodromal markers of α-synucleinopathy neurodegeneration in 'isolated' recurrent dream enactment behaviors among first degree relatives of patients with REM sleep behavior disorder - preliminary validation of prodromal rbd concept

Clinical Correlates of Dream Enactment Behaviors in Previously Deployed OEF/OIF/OND Veterans: An Exploratory Analysis.

Veterans with posttraumatic stress disorder (PTSD) frequently report dream enactment behavior (DEB). Although DEBs are associated with PTSD symptoms, their relationship with other sleep disorders, including REM behavior disorder, warrants reexamination of their clinical correlates. The investigators used a cross-sectional, exploratory analysis to compare demographic and clinical characteristics of veterans endorsing regularly occurring DEB compared with those endorsing no or infrequent DEB. The participants comprised a convenience sample of servicemembers who were previously deployed to Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn (OEF/OIF/OND) and enrolled in an ongoing cohort study. Of the 78 eligible participants, 19 (24.4%) endorsed DEBs occurring at least once per week in the past month. Compared with participants who reported no or infrequent DEBs, participants with regularly occurring DEBs had poorer sleep quality, greater PTSD severity, a higher number of reported mild traumatic brain injuries (mTBI) with loss of consciousness, and a higher likelihood of being diagnosed with sleep disorders. After adjustment for global sleep quality, a significant association persisted between DEBs and the number of mTBI with loss of consciousness but not between DEBs and the severity of PTSD symptoms. These results suggest that mTBI may disrupt neural circuits regulating sleep among OIF/OEF/OND veterans. Prospective, polysomnographic assessment of muscle tone and behavioral events during REM sleep is needed to characterize the physiology of DEBs in this population.

Faster cognitive decline in dementia due to Alzheimer disease with clinically undiagnosed Lewy body disease

BackgroundNeuropathology has demonstrated a high rate of comorbid pathology in dementia due to Alzheimer’s disease (ADD). The most common major comorbidity is Lewy body disease (LBD), either as dementia with Lewy bodies (AD-DLB) or Alzheimer’s disease with Lewy bodies (AD-LB), the latter representing subjects with ADD and LBD not meeting neuropathological distribution and density thresholds for DLB. Although it has been established that ADD subjects with undifferentiated LBD have a more rapid cognitive decline than those with ADD alone, it is still unknown whether AD-LB subjects, who represent the majority of LBD and approximately one-third of all those with ADD, have a different clinical course.MethodsSubjects with dementia included those with “pure” ADD (n = 137), AD-DLB (n = 64) and AD-LB (n = 114), all with two or more complete Mini Mental State Examinations (MMSE) and a full neuropathological examination.ResultsLinear mixed models assessing MMSE change showed that the AD-LB group had significantly greater decline compared to the ADD group (β = -0.69, 95% CI: -1.05, -0.33, p<0.001) while the AD-DLB group did not (β = -0.30, 95% CI: -0.73, 0.14, p = 0.18). Of those with AD-DLB and AD-LB, only 66% and 2.1%, respectively, had been diagnosed with LBD at any point during their clinical course. Compared with clinically-diagnosed AD-DLB subjects, those that were clinically undetected had significantly lower prevalences of parkinsonism (p = 0.046), visual hallucinations (p = 0.0008) and dream enactment behavior (0.013).ConclusionsThe probable cause of LBD clinical detection failure is the lack of a sufficient set of characteristic core clinical features. Core DLB clinical features were not more common in AD-LB as compared to ADD. Clinical identification of ADD with LBD would allow stratified analyses of ADD clinical trials, potentially improving the probability of trial success.

Clinical profiles of late-onset psychiatric patients exhibiting incidental REM sleep without atonia.

Rapid eye movement (REM) sleep without atonia (RWA), which is a hallmark of REM sleep behavior disorder (RBD) on polysomnography (PSG), may represent specific characteristics of prodromal Parkinson's disease (PD)/dementia with Lewy bodies (DLB), even when dream-enactment behavior is absent. We investigated the clinical profiles associated with PD/DLB in late-onset psychiatric patients exhibiting incidental RWA. Among patients who underwent PSG in our psychiatric ward, eight with incidental RWA, nine with idiopathic RBD, and seven with PD or DLB who had preceding RBD were included. Clinical variables, including the percentage of RWA in the total REM sleep (%RWA), were compared among the three groups. The frequency of depressive disorders as a primary psychiatric diagnosis and antidepressant usage were significantly higher in the incidental RWA group than in the other groups. There were no differences in the prevalence of supportive features of DLB among the three groups. The median %RWA was significantly lower in the incidental RWA group than in the other groups. Although the cardiac 123I-metaiodobenzylguanidine uptake was significantly higher in the incidental RWA group compared with the other groups, the groups showed overlap in the specific binding ratios on dopamine transporter imaging. All patients in the three groups exhibited cingulate island sign ratios on brain perfusion single-photon emission computed tomography within a threshold of 0.281, which is the optimal cut-off value for a diagnosis of DLB. In this series, late-onset psychiatric patients with incidental RWA partially shared common clinical profiles with idiopathic RBD and PD/DLB.

0957 “To Be, Or Not To Be? Case Series Of Patients With Discrepancy Between Clinical Vs. Psg Criteria For Diagnosis Of Rem Behavior Disorder (RBD).”

The ICSD 3 lists the presence of REM without atonia (RWA) on PSG, as an essential criterion for the diagnosis of RBD. However, the scoring criteria for RWA are not clearly defined in the AASM scoring manual (2012). We describe three patients with clinical diagnosis of RBD, who did not fulfill the PSG criteria for RWA. They reported improvement on treatment with melatonin. These three males, aged 68, 73 and 73 years, complained of >1 year history of witnessed semi-purposeful behaviors in sleep, that correlated with their dream content. One patient had a history of Parkinson’s Disease (PD) with worsening episodes, despite being on dopaminergic therapy. All three patients underwent PSG with Multiple Muscle Montage (MMM) which includes upper extremities EMG, in our lab. All 3 patients PSG’s revealed excessive transient muscle activity in some epochs of REM sleep as defined by AASM manual, but these epochs did not add up to >50% of the total REM epochs, and hence did not meet the PSG criteria for RWA in our lab. Of these, 2 patients had neither OSA nor PD. In 1 of the 2 PSG’s, dream enactment behavior (DEB) was noted. The PD patient had mild OSA and underwent a CPAP study with MMM, which revealed DEB but also did not meet the criteria for RWA. The AASM definition of RWA is deficient in specifying: 1) the percentage of total REM epochs that should show excessive twitching 2) the minimal duration of REM sleep required for application of this definition 3) whether the definition is applicable if the patient has comorbid OSA or is on dopaminergic medications 4) whether the montage for assessment of RWA should include upper extremities EMG. These deficiencies may lead to underestimation of RBD in some labs, and reduced inter-scorer reliability between labs. Hence, further clarification of the definition is needed before RWA is deemed as an essential criterion for the diagnosis of RBD. Support (If Any)

1035 Dream Enactment Behavior during non-REM sleep in the setting of serotonin noradrenergic reuptake inhibitor therapy &amp; REM Sleep Suppression

1035 Dream Enactment Behavior during non-REM sleep in the setting of serotonin noradrenergic reuptake inhibitor therapy &amp; REM Sleep Suppression

Clinical and video-polysomnographic analysis of rapid eye movement sleep behavior disorder and other sleep disturbances in dementia with Lewy bodies.

The main objective of this study was to study rapid eye movement (REM) sleep behavior disorder (RBD) and other sleep disorders in dementia with Lewy bodies (DLB). Consecutive patients with DLB and mild dementia severity were recruited irrespective of sleep complaints. Patients underwent clinical interview, assessment of sleep scales, and video-polysomnography (V-PSG). RBD was diagnosed with V-PSG based on electromyographic and audiovisual analysis. Thirty-five patients (65.7% men; mean age 77.7 ± 6.1 years) were evaluated. Poor sleep quality (54.3%), hypersomnia (37.1%), snoring (60%), and abnormal nocturnal behaviors (77.1%) were reported. Sleep-wake architecture abnormalities occurred in 75% patients and consisted of occipital slowing on awake electroencephalography (EEG; 34.4%), the absence of sleep spindles and K complexes (12.9%), slow frequency sleep spindles (12.9%), delta activity in REM sleep (19.2%), and REM sleep without atonia (44%). Three patients showed hallucinatory-like behaviors and 10 patients showed abnormal behaviors during arousals mimicking RBD. RBD was diagnosed in 50% of those patients in whom sufficient REM sleep was attained. Of these, 72.7% were not aware of displaying dream-enacting behaviors and in 63.7% RBD preceded the onset of cognitive impairment. For RBD diagnosis, the sensitivity of Mayo Sleep Questionnaire was 50%, specificity was 66.7%, positive predictive value was 83.3%, and negative predictive value was 28%. False-positive RBD cases according to clinical history had hallucinatory-like behaviors, severe obstructive sleep apnea, and prominent periodic limb movements in sleep. Occipital EEG frequency while awake and rate of electromyographic activity in REM sleep were negatively correlated, suggesting a common subcortical origin. In DLB, RBD and sleep-wake disorders are common, heterogeneous, and complex, challenging their identification without performing V-PSG.

Parkinsonism Risk Factors in Salt Lake City, Utah: A Community-Based Study.

Background: The prevalence of dream enactment behavior and other risk factors for a parkinsonian disorder is not well documented. Methods: A survey on prevalence of parkinsonism risk factors was designed using two validated instruments (REM behavior disorder single item question, bowel movement frequency for constipation) and three exploratory instruments (for hallucinations, cognitive and olfactory complaints.) It was sent by mail and email to patients aged 50 and over at two University of Utah community clinics in Salt Lake City. A total of 7888 unique patients were sent the survey, and 1607 responses were recorded (response rate 20%). Those whose age was missing (n = 117) or less than 50 years (n = 10) were excluded from the analysis. Results: Of the 1406 without personal diagnosis of neurodegenerative disease 62.7% were female, and median age was 63. Family history (FH) of Parkinson’s disease was endorsed by 9%, constipation (defined as a bowel movement less than once per day) by 19%, mild cognitive complaints (MCI) 15.8%, dream enactment 13.7%, subjective hyposmia or anosmia 18.2%, and at least one potential psychotic symptom in 37.6%. Multivariable logistic regression showed male gender, mild cognitive complaints, hearing voices, and at least one potentially psychotic symptom to be significantly associated with dream enactment. Conclusions: This survey shows that dream enactment, a strong predictor of risk for synucleinopathy, is relatively common in the older population; because such individuals rarely come to medical attention of a sleep clinic, such survey research may be useful to identify and recruit at-risk individuals for trials aimed at preventing neurodegenerative disease.

Trauma-Associated Sleep Disorder: A Posttraumatic Stress/REM Sleep Behavior Disorder Mash-Up?

Trauma-associated sleep disorder (TASD) is a parasomnia sharing characteristics of post-traumatic stress disorder (PTSD) and REM sleep behavior disorder (RBD) including dream-enactment behavior (DEB). Here we report REM sleep without atonia (RSWA) and other neurological features in a patient with complex vocal and motor DEB following traumatic combat military exposure. Post-discharge, his wife observed frequent yelling and jerking during sleep with dream mentation reminiscent of traumatic military experiences. He was initially diagnosed with PTSD. Polysomnography demonstrated RSWA and severe obstructive sleep apnea treated with nasal continuous positive airway pressure (CPAP). Dream-enactment behavior severity and frequency was reduced, but still persisted despite nasal CPAP and sequential fluoxetine, escitalopram, prazosin, and melatonin trials. Our case demonstrated overlapping clinical features of PTSD and RBD with polysomnography features of RSWA supportive of idiopathic RBD but no "soft signs" suggesting underlying synucleinopathy. Longitudinal follow-up of larger case series must clarify whether TASD consistently manifests REM sleep atonia loss and determine the phenoconversion risk for synucleinopathy neurodegeneration. A commentary on this article appears in this issue on page 181.

Parasomnia overlap disorder with adolescent-onset presumed REM sleep behavior disorder converting to Parkinson's disease after 48 years

BackgroundIt is now recognized that the vast majority of individuals with typical RBD will develop a synucleinopathy; usually 11–16 years after symptom onset. Parasomnia Overlap Disorder (POD) with adolescent-onset dream enactment behavior with phenoconversion to neurodegenerative disease after a long latency has not been previously described. PatientWe present a case of a 65-year-old man with presumptive POD who had co-morbid childhood onset sleep walking and adolescent-onset dream enactment behavior beginning at age 17, with subsequent evolution to an increasingly troublesome REM sleep behavior disorder (RBD) at age 64 with Parkinson's Disease (PD) developing a year later. ResultsPolysomnography performed at age 64 was consistent with a diagnosis of RBD. Dream enactment behavior preceded PD diagnosis by at least 48 years. Our case represents the youngest reported RBD case who developed PD. ConclusionsWe report the first case of adolescent onset, presumed RBD in the context of presumptive POD developing neurodegenerative disease. Adolescent-onset RBD may have similar prognostic implications as typical RBD, where future phenoconversion to a synucleinopathy is expected.

Sleep disturbances are common in patients with autoimmune encephalitis.

Autoimmune encephalitis (AE) is increasingly recognized as an important cause of subacute cognitive decline, seizures, and encephalopathy, with an ever-broadening clinical phenotype. Sleep disturbances are reported in AE patients, including rapid eye movement sleep behavior disorder, hypersomnia, fragmented sleep, and sleep-disordered breathing; however, the prevalence of sleep disturbances and contributions to outcomes in AE patients remain unknown. There is a need to determine the prevalence of sleep disturbances in AE patients, and to clarify the relationship between specific autoantibodies and disruptions in sleep. Clinical history, results of serum and cerebrospinal fluid testing, electroencephalography, and neuroimaging were reviewed from 26 AE patients diagnosed and managed at our tertiary care hospital. Polysomnography was performed in patients with clinical indications, yielding data from 12 patients. The median age of AE patients was 53years (range 18-83). Autoantibodies against intracellular antigens (including Ma and Hu autoantibodies) were identified in 6/26 (23%) patients, while autoantibodies against cell-surface neuronal antigens (including NMDAR and LGI1) were identified in 20/26 (77%) patients. New sleep complaints were reported by 19/26 (73%) AE patients, including gasping or snoring (9/19, 47%), dream enactment behavior (6/19, 32%), insomnia (5/19, 29%), hypersomnia (4/19, 21%), other parasomnias (4/19, 21%), and dream-wake confusional states (2/19, 11%). Dream enactment behaviors were particularly common in AE associated with LGI1 autoantibodies, reported in 4/7 (57%) patients. Polysomnography showed reduced total sleep time, stage 3 and rapid eye movement sleep, and prominent sleep fragmentation. Sleep disturbances are common in AE, warranting active surveillance in affected patients. Improved identification and treatment of sleep disorders may reduce morbidity associated with AE and improve long-term outcomes.

Quetiapine-induced behavioral disorder during sleep.

Quetiapine-induced behavioral disorder during sleep.

Mild Head Injury Induced Rapid Eye Movement Sleep Behaviour Disorder

Rapid eye movement (REM) sleep behaviour disorder (RBD) is a parasomnia characterised by REM sleep without atonia, causing dream-enacting behaviours (DEBs) or vocalisation. The aetiology of RBD is largely unknown, likely a result from breakdown of the circuits underlying REM sleep atonia. It is also strongly associated with neurodegenerative disorders. Recent studies suggested that head injury could be a risk factor for RBD. We present a case of new-onset RBD, triggered by mild head injury in a patient with well-managed severe obstructive sleep apnoea (OSA). Our case provides a rare opportunity to examine the link between head injury and RBD.

Sleep Disorders

Recent research has generated an enormous fund of knowledge about the neurobiology of sleep and wakefulness. Sleeping and waking brain circuits can now be studied by sophisticated neuroimaging techniques that map different areas of the brain during different sleep states and stages. Although the exact biologic functions of sleep are not known, sleep is essential, and sleep deprivation leads to impaired attention and decreased performance. Sleep is also believed to have restorative, conservative, adaptive, thermoregulatory, and consolidative functions. This review discusses the physiology of sleep, including its two independent states, rapid eye movement (REM) and non–rapid eye movement (NREM) sleep, as well as functional neuroanatomy, physiologic changes during sleep, and circadian rhythms. The classification and diagnosis of sleep disorders are discussed generally. The diagnosis and treatment of the following disorders are described: obstructive sleep apnea syndrome, narcolepsy-cataplexy sydrome, idiopathic hypersomnia, restless legs syndrome (RLS) and periodic limb movements in sleep, circadian rhythm sleep disorders, insomnias, nocturnal frontal lobe epilepsy, and parasomnias. Sleep-related movement disorders and the relationship between sleep and psychiatric disorders are also discussed. Tables describe behavioral and physiologic characteristics of states of awareness, the international classification of sleep disorders, common sleep complaints, comorbid insomnia disorders, causes of excessive daytime somnolence, laboratory tests to assess sleep disorders, essential diagnostic criteria for RLS and Willis-Ekbom disease, and drug therapy for insomnia. Figures include polysomnographic recording showing wakefulness in an adult; stage 1, 2, and 3 NREM sleep in an adult; REM sleep in an adult; a patient with sleep apnea syndrome; a patient with Cheyne-Stokes breathing; a patient with RLS; and a patient with dream-enacting behavior; schematic sagittal section of the brainstem of the cat; schematic diagram of the McCarley-Hobson model of REM sleep mechanism; the Lu-Saper “flip-flop” model; the Luppi model to explain REM sleep mechanism; and a wrist actigraph from a man with bipolar disorder. This review contains 14 highly rendered figures, 8 tables, 115 references, and 5 MCQs.

Abnormal activation of motor cortical network during phasic REM sleep in idiopathic REM sleep behavior disorder.

We investigated electroencephalography (EEG) power spectral density and functional connectivity during phasic and tonic rapid eye movement (REM) sleep, and examined any differences between patients with idiopathic REM sleep behavior disorder (iRBD) and controls. EEG data from 13 people with iRBD (mean age, 66.3 years; men, 84.6%) and 10 controls (mean age, 62.3 years; men, 70%) were analyzed. We selected thirty 3 s miniepochs of both tonic and phasic REM sleep. We estimated relative power for six frequency bands. For functional connectivity analysis, we calculated weighted phase lag index (wPLI) and conducted pairwise comparisons between the two groups. EEG power spectral analysis revealed significant interactions between the REM sleep state (phasic vs. tonic) and group at sigma (p = 0.009) and beta (p = 0.002) bands. Sigma- and beta-power decrease during phasic REM sleep was more pronounced and extensive in people with iRBD than in controls. Regarding functional connectivity, there were significant interactions between the REM sleep state and group at alpha (p = 0.029), sigma (p = 0.047), beta (p = 0.015), and gamma (p = 0.046) bands. The average wPLI was significantly higher during phasic REM sleep than during tonic REM sleep, which was observed in people with iRBD but not in controls. The altered functional connections mainly involved the frontal and parietal regions at beta and gamma bands. Our findings provide neurophysiological evidence for pathological motor cortex activation during phasic REM sleep which may be associated with generation of dream-enacting behaviors in iRBD.

REM sleep behavior disorder: relevance to epileptologists

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia that features loss of the generalized skeletal muscle atonia of mammalian REM sleep, with release of injurious dream-enacting behaviors. Video-polysomnography is necessary to confirm the diagnosis. Our aim was to provide a relevant update on RBD for electroencephalography (EEG) and epilepsy specialists. This study comprised a focused literature review. Typical and atypical RBD clinical profiles are presented and discussed. Official diagnostic criteria are listed and experimental animal models are reviewed. The differential diagnosis, including nocturnal seizures, is considered, and EEG, evoked potential, and sleep spindle findings are presented. Emphasis is placed on idiopathic RBD as a common herald of future alpha-synucleinopathy neurodegeneration (Parkinson’s disease, dementia with Lewy bodies, multiple system atrophy). Furthermore, we describe the formation of the International RBD Study Group in 2009 with yearly research symposia. RBD comprises a fascinating, multidimensional parasomnia that needs to be considered in the differential diagnosis of nocturnal epilepsy with abnormal sleep-related behaviors in order to facilitate identifying the correct diagnosis and to initiate proper therapy.

REM sleep behavior disorder in patients with Parkinson’s disease: clinical and polysomnographic characteristics

The objectives of this study were to describe the characteristics of RBD in a group of PD patients and verify the accuracy of the clinical interview in this group, determine the causes of failure of the interview, as well as to verify the clinical and polysomnographic differences between the groups of PD patients with and without RBD. So, a cross-sectional study was conducted in 88 consecutive PD patients from the outpatient clinic, during a period of 21 months. Participants underwent a clinical interview, assessment based on standardized scales (Epworth Sleepiness Scale, Parkinson’s disease Questionnaire, Pittsburgh Sleep Quality Index), and video polysomnography. Out of the 88 participants, 55 underwent vPSG which confirmed a diagnosis of RBD. The clinical interview had a high sensitivity (87.5%) but a low specificity (42.1%) for RBD diagnosis and thus the clinical interview alone may miss those without episodes of dream-enacting behavior. We note in this group a higher proportion of men (54.5%) and an average age of 60.4 years ± 10.6. In 54% of patients, RBD preceded motor symptoms of PD. In addition, patients with PD and RBD had lower Apnea–Hypopnea Index in REM sleep and a higher equivalent dose of levodopa than PD patients without RBD. RBD is a prevalent condition in patients with PD, requiring polysomnography for diagnostic confirmation, and is associated with certain particularities in PD.

From Rapid Eye Movement Sleep Behavior Disorder to Parkinson's Disease: Possible Predictive Markers of Conversion.

Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) manifests as unpleasant dreams and dream-enacting behaviors during REM sleep. iRBD is currently recognized as a prodromal stage of Parkinson's disease (PD), and the majority of iRBD patients will develop PD. However, there is an approximately 10 year interval between iRBD onset and established PD, which provides neurologists a window for intervention prior to irreversible neuron damage in prodromal PD patients. In this Review, we summarize possible predictive markers of PD in iRBD on clinical assessment, heredity, neuroimaging, and electrophysiology. We hope this summary can help researchers and clinical physicians better understand the risk factors for conversion from iRBD to PD and indicate directions for neuroprotective strategies and the prediction of disease progression.

REM sleep behaviour disorder.

Rapid eye movement (REM) sleep behaviour disorder (RBD) is a parasomnia that is characterized by loss of muscle atonia during REM sleep (known as REM sleep without atonia, or RSWA) and abnormal behaviours occurring during REM sleep, often as dream enactments that can cause injury. RBD is categorized as either idiopathic RBD or symptomatic (also known as secondary) RBD; the latter is associated with antidepressant use or with neurological diseases, especially α-synucleinopathies (such as Parkinson disease, dementia with Lewy bodies and multiple system atrophy) but also narcolepsy type 1. A clinical history of dream enactment or complex motor behaviours together with the presence of muscle activity during REM sleep confirmed by video polysomnography are mandatory for a definite RBD diagnosis. Management involves clonazepam and/or melatonin and counselling and aims to suppress unpleasant dreams and behaviours and improve bedpartner quality of life. RSWA and RBD are now recognized as manifestations of an α-synucleinopathy; most older adults with idiopathic RBD will eventually develop an overt neurodegenerative syndrome. In the future, studies will likely evaluate neuroprotective therapiesinpatients with idiopathic RBD to prevent or delay α-synucleinopathy-related motorandcognitivedecline.

Difference in severity of sleep apnea in patients with rapid eye movement sleep behavior disorder with or without parkinsonism

ObjectiveRapid eye movement sleep behavior disorder (RBD) is a common sleep disturbance in patients with neurodegenerative disorders. We aimed to compare sleep parameters among the different types of RBD patients. MethodsA total of 122 patients with dream enactment behavior were screened. Of these, 92 patients who were diagnosed with RBD by polysomnography were included in this study. Enrolled patients with RBD were classified into four groups based on the following diagnoses: idiopathic RBD (iRBD); RBD with Parkinson disease (PD-RBD); multiple system atrophy (MSA) with RBD (MSA-RBD); and dementia with Lewy bodies (DLB) with RBD (DLB-RBD). Various clinical and polysomnographic parameters were compared. ResultsAmong the 92 patients with RBD, 35 had iRBD, 25 had PD-RBD, 17 had MSA-RBD, and 15 had DLB-RBD. The mean apnea−hypopnea index of atypical parkinsonism with RBD (AP-RBD) group was 16.2 ± 17.7 events/h (MSA-RBD, 14.0 ± 16.6; DLB-RBD, 18.8 ± 19.1), which was significantly higher than the other groups (p < 0.05). The proportion of patients with 100% supine sleep in the AP-RBD group (44%) was higher than that in the iRBD group (14%; p = 0.030). The proportion of OSA with 100% supine sleep position was significantly higher in the MSA-RBD and DLB-RBD groups than in the iRBD group (p = 0.042 and p = 0.029, respectively). ConclusionOur study demonstrated that patients in the MSA-RBD and DLB-RBD groups had a tendency to sleeping in the supine position and a higher vulnerability to OSA compared to other RBD groups. Further cohort studies are needed to evaluate the influence of these factors on the development of parkinsonism.