REM sleep behavior disorder portends poor prognosis in Parkinson’s disease: A systematic review

Anticipating Tomorrow: Tailoring Parkinson's Symptomatic Therapy Using Predictors of Outcome

BACKGROUND

Although research into Parkinson's disease (PD) subtypes and outcome predictions has continued to advance, recommendations for using outcome prediction to guide current treatment decisions remain sparse.

OBJECTIVES

To provide expert opinion-based recommendations for individually tailored PD symptomatic treatment based on knowledge of risk prediction and subtypes.

METHODS

Using a modified Delphi approach, members of the Movement Disorders Society (MDS) Task Force on PD subtypes generated a series of general recommendations around the question: "Using what you know about genetic/biological/clinical subtypes (or any individual-level predictors of outcome), what advice would you give for selecting symptomatic treatments for an individual patient now, based on what their subtype or individual characteristics predict about their future disease course?" After four iterations and revisions, those recommendations with over 75% endorsement were adopted.

RESULTS

A total of 19 recommendations were endorsed by a group of 13 panelists. The recommendations primarily centered around two themes: (1) incorporating future risk of cognitive impairment into current treatment plans; and (2) identifying future symptom clusters that might be forestalled with a single medication.

CONCLUSIONS

These recommendations provide clinicians with a framework for integrating future outcomes into patient-specific treatment choices. They are not prescriptive guidelines, but adaptable suggestions, which should be tailored to each individual. They are to be considered as a first step of a process that will continue to evolve as additional stakeholders provide new insights and as new information becomes available. As individualized risk prediction advances, the path to better tailored treatment regimens will become clearer.

The basal forebrain cholinergic system as target for cell replacement therapy in Parkinson's disease

In recent years there has been a renewed interest in the basal forebrain cholinergic system as a target for the treatment of cognitive impairments in patients with Parkinson's disease, due in part to the need to explore novel approaches to treat the cognitive symptoms of the disease and in part to the development of more refined imaging tools that have made it possible to monitor the progressive changes in the structure and function of the basal forebrain system as they evolve over time. In parallel, emerging technologies allowing the derivation of authentic basal forebrain cholinergic neurons from human pluripotent stem cells are providing new powerful tools for the exploration of cholinergic neuron replacement in animal models of Parkinson's disease-like cognitive decline. In this review, we discuss the rationale for cholinergic cell replacement as a potential therapeutic strategy in Parkinson's disease and how this approach can be explored in rodent models of Parkinson's disease-like cognitive decline, building on insights gained from the extensive animal experimental work that was performed in rodent and primate models in the 1980s and 90s. Although therapies targeting the cholinergic system have so far been focused mainly on patients with Alzheimer's disease, Parkinson's disease with dementia may be a more relevant condition. In Parkinson's disease with dementia, the basal forebrain system undergoes progressive degeneration and the magnitude of cholinergic cell loss has been shown to correlate with the level of cognitive impairment. Thus, cell therapy aimed to replace the lost basal forebrain cholinergic neurons represents an interesting strategy to combat some of the major cognitive impairments in patients with Parkinson's disease dementia.

Whole brain pattern of iron accumulation in REM sleep behavior disorder

Isolated REM sleep behavior disorder (iRBD) is an early stage of synucleinopathy with most patients progressing to Parkinson's disease (PD) or related conditions. Quantitative susceptibility mapping (QSM) in PD has identified pathological iron accumulation in the substantia nigra (SN) and variably also in basal ganglia and cortex. Analyzing whole-brain QSM across iRBD, PD, and healthy controls (HC) may help to ascertain the extent of neurodegeneration in prodromal synucleinopathy. 70 de novo PD patients, 70 iRBD patients, and 60 HCs underwent 3 T MRI. T1 and susceptibility-weighted images were acquired and processed to space standardized QSM. Voxel-based analyses of grey matter magnetic susceptibility differences comparing all groups were performed on the whole brain and upper brainstem levels with the statistical threshold set at family-wise error-corrected p-values <.05. Whole-brain analysis showed increased susceptibility in the bilateral fronto-parietal cortex of iRBD patients compared to both PD and HC. This was not associated with cortical thinning according to the cortical thickness analysis. Compared to iRBD, PD patients had increased susceptibility in the left amygdala and hippocampal region. Upper brainstem analysis revealed increased susceptibility within the bilateral SN for both PD and iRBD compared to HC; changes were located predominantly in nigrosome 1 in the former and nigrosome 2 in the latter group. In the iRBD group, abnormal dopamine transporter SPECT was associated with increased susceptibility in nigrosome 1. iRBD patients display greater fronto-parietal cortex involvement than incidental early-stage PD cohort indicating more widespread subclinical neuropathology. Dopaminergic degeneration in the substantia nigra is paralleled by susceptibility increase, mainly in nigrosome 1.

GBA1 rs3115534 Is Associated with REM Sleep Behavior Disorder in Parkinson's Disease in Nigerians

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) is an early feature of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Damaging coding variants in Glucocerebrosidase (GBA1) are a genetic risk factor for RBD. Recently, a population-specific non-coding risk variant (rs3115534) was found to be associated with PD risk and earlier onset in individuals of African ancestry.

OBJECTIVES

We aimed to investigate whether the GBA1 rs3115534 PD risk variant is associated with RBD in persons with PD.

METHODS

We studied 709 persons with PD and 776 neurologically healthy controls from Nigeria. All DNA samples were genotyped and imputed, and the GBA1 rs3115534 risk variant was extracted. The RBD screening questionnaire (RBDSQ) was used to assess symptoms of possible RBD.

RESULTS

RBD was present in 200 PD (28.2%) and 51 (6.6%) controls. We identified that the non-coding GBA1 rs3115534 risk variant is associated with possible RBD in individuals of Nigerian origin (β, 0.3640; standard error [SE], 0.103, P = 4.093e-04), as well as in all samples after adjusting for PD status (β, 0.2542; SE, 0.108; P = 0.019) suggesting that although non-coding, this variant may have the same downstream consequences as GBA1 coding variants.

CONCLUSIONS

Our results indicate that the non-coding GBA1 rs3115534 risk variant is associated with an increasing number of RBD symptoms in persons with PD of Nigerian origin. Further research is needed to assess if this variant is also associated with polysomnography-defined RBD and with RBD symptoms in DLB. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Transitioning from Subtyping to Precision Medicine in Parkinson's Disease: A Purpose-Driven Approach

The International Parkinson and Movement Disorder Society (MDS) created a task force (TF) to provide a critical overview of the Parkinson's disease (PD) subtyping field and develop a guidance on future research in PD subtypes. Based on a literature review, we previously concluded that PD subtyping requires an ultimate alignment with principles of precision medicine, and consequently novel approaches were needed to describe heterogeneity at the individual patient level. In this manuscript, we present a novel purpose-driven framework for subtype research as a guidance to clinicians and researchers when proposing to develop, evaluate, or use PD subtypes. Using a formal consensus methodology, we determined that the key purposes of PD subtyping are: (1) to predict disease progression, for both the development of therapies (use in clinical trials) and prognosis counseling, (2) to predict response to treatments, and (3) to identify therapeutic targets for disease modification. For each purpose, we describe the desired product and the research required for its development. Given the current state of knowledge and data resources, we see purpose-driven subtyping as a pragmatic and necessary step on the way to precision medicine. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Differences in brain aging between sexes in Parkinson's disease

Parkinson's disease (PD) is linked to faster brain aging. Male sex is associated with higher prevalence, severe symptoms, and a faster progression rate in PD. There remains a significant gap in understanding the function of sex in the process of brain aging in PD. The structural T1-weighted MRI-driven brain-predicted age difference (i.e., Brain-PAD: the actual age subtracted from the brain-predicted age) was computed in a group of 373 people with PD (mean age ± SD: 61.37 ± 9.81, age range: 33-85, 34% female) from the Parkinson's Progression Marker Initiative database using a robust brain-age estimation framework that was trained on 949 healthy subjects. Linear regression models were used to investigate the association between Brain-PAD and clinical variables in PD, stratified by sex. Males with Parkinson's disease (PD-M) exhibited a significantly higher mean Brain-PAD than their female counterparts (PD-F) (t(256) = 2.50, p = 0.012). In the propensity score-matched PD-M group (PD-M*), Brain-PAD was found to be associated with a decline in general cognition, a worse degree of sleep behavior disorder, reduced visuospatial acuity, and caudate atrophy. Conversely, no significant links were observed between these factors and Brain-PAD in the PD-F group. Having 'older' looking brains in PD-M than PD-F supports the idea that sex plays a vital function in PD, such that the PD mechanism may be different in males and females. This study has the potential to broaden our understanding of dissimilarities in brain aging between sexes in the context of PD.

Impact of REM Sleep Behavior and Sleep Talking on Mortality in Parkinson's Disease

Background REM sleep behavior disorder (RBD) is a prodromal marker for Parkinson's disease (PD) and other alpha-synucleinopathies. Sleep talking (ST) is an isolated symptom and is frequent in PD and RBD. Here, we investigate the associations of ST and RBD with the mortality of PD patients. Patients and methods A total of 1,500 PD patients were randomly selected from the registry of the Finnish Parkinson's Association. Of the 855 that participated at baseline, 645 gave permission for follow-up studies. We gathered a completely filled sleep questionnaire and mortality information from 384 subjects. The Nelson-Aalen test and Cox hazard ratios (HR) were used for mortality analyses. Results The mean follow-up time was 4.3 years (0.3-7.0). PD patients with RBD or frequent ST had more non-motor symptoms. Depression, hallucinations, constipation, and excessive daytime sleepiness were more prevalent among subjects with RBD. Subjects with RBD and frequent ST (talking in their sleep ≥ once per week) had increased mortality (HR: 1.90, 95% CI: 1.18-3.06). RBD without frequent ST was not associated with mortality (HR: 0.77, 95% CI: 0.4-1.5). Frequent ST was associated with increased mortality when adjusted for age, PD duration, depression, gender, RBD, BMI, and hallucinations (HR: 2.22, 95% CI: 1.10-4.51). Additionally, age, duration of PD, arterial hypertension, and lower BMI were associated with increased mortality. Male gender, dopaminergic medication, depression, and hallucinations were not significantly associated with mortality. Conclusions RBD with frequent ST and ST alone appear to be risk factors for mortality in PD. Frequent ST may be a sign representing wider neurodegeneration. RBD subjects and frequent sleep talkers demonstrated more non-motor symptoms compared to PD without RBD or ST. Our findings have clinical implications. It remains to be seen if frequent ST indicates a poorer prognosis. Prospective studies are needed to find whether frequent ST is also a risk factor for developing PD.

Obstructive Sleep Apnea and Striatal Dopamine Availability in Parkinson's Disease

BACKGROUND

Sleep disorders are frequently associated with Parkinson's disease. Obstructive sleep apnea syndrome is one of these sleep disorders and is associated with the severity of motor symptoms in Parkinson's disease. Obstructive sleep apnea can lead to dopaminergic neuronal cell degeneration and may impair the clearance of α-synuclein in Parkinson's disease. Striatal dopamine uptake is a surrogate marker of nigral dopaminergic cell damage.

OBJECTIVE

We aimed to investigate the differences in striatal dopamine availability between Parkinson's disease patients with or without obstructive sleep apnea.

METHODS

A total of 85 de novo and nonmedicated Parkinson's disease patients were enrolled. Full-night polysomnography was performed for all patients, and obstructive sleep apnea was diagnosed as apnea/hypopnea index ≥5. Positron emission tomography was performed with 18 F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane, and the regional standardized-uptake values were analyzed using a volume-of-interest template and compared between groups with or without obstructive sleep apnea.

RESULTS

Dopamine availability in the caudate nucleus of the obstructive sleep apnea group was significantly lower than that of the nonobstructive sleep apnea group. On subgroup analysis, such association was found in female but not in male patients. In other structures (putamen, globus pallidus, and thalamus), dopamine availability did not differ between the two groups.

CONCLUSION

This study supports the proposition that obstructive sleep apnea can contribute to reduced striatal dopamine transporter availability in Parkinson's disease. Additional studies are needed to assess the causal association between obstructive sleep apnea and the neurodegenerative process in Parkinson's disease. © 2023 International Parkinson and Movement Disorder Society.

Mood disturbances in Parkinson's disease: From prodromal origins to application of animal models

Parkinson's disease (PD) is a complex illness with a constellation of environmental insults and genetic vulnerabilities being implicated. Strikingly, many studies only focus on the cardinal motor symptoms of the disease and fail to appreciate the major non-motor features which typically occur early in the disease process and are debilitating. Common comorbid psychiatric features, notably clinical depression, as well as anxiety and sleep disorders are thought to emerge before the onset of prominent motor deficits. In this review, we will delve into the prodromal stage of PD and how early neuropsychiatric pathology might unfold, followed by later motor disturbances. It is also of interest to discuss how animal models of PD capture the complexity of the illness, including depressive-like characteristics along with motor impairment. It remains to be determined how the underlying PD disease processes contributes to such comorbidity. But some of the environmental toxicants and microbial pathogens implicated in PD might instigate pro-inflammatory effects favoring α-synuclein accumulation and damage to brainstem neurons fueling the evolution of mood disturbances. We posit that comprehensive animal-based research approaches are needed to capture the complexity and time-dependent nature of the primary and co-morbid symptoms. This will allow for the possibility of early intervention with more novel and targeted treatments that fit with not only individual patient variability, but also with changes that occur over time with the evolution of the disease.

Clinical Evaluation of Sleep Disorders in Parkinson’s Disease

The paradigm of the framing of Parkinson’s disease (PD) has undergone significant revision in recent years, making this neurodegenerative disease a multi-behavioral disorder rather than a purely motor disease. PD affects not only the “classic” substantia nigra at the subthalamic nuclei level but also the nerve nuclei, which are responsible for sleep regulation. Sleep disturbances are the clinical manifestations of Parkinson’s disease that most negatively affect the quality of life of patients and their caregivers. First-choice treatments for Parkinson’s disease determine amazing effects on improving motor functions. However, it is still little known whether they can affect the quantity and quality of sleep in these patients. In this perspective article, we will analyze the treatments available for this specific clinical setting, hypothesizing a therapeutic approach in relation to neurodegenerative disease state.

Chronobiology of Parkinson's disease: Past, present and future

Parkinson's disease is a neurodegenerative disorder predominately affecting midbrain dopaminergic neurons that results in a broad range of motor and non-motor symptoms. Sleep complaints are among the most common non-motor symptoms, even in the prodromal period. Sleep alterations in Parkinson's disease patients may be associated with dysregulation of circadian rhythms, intrinsic 24-h cycles that control essential physiological functions, or with side effects from levodopa medication and physical and mental health challenges. The impact of circadian dysregulation on sleep disturbances in Parkinson's disease is not fully understood; as such, we review the systems, cellular and molecular mechanisms that may underlie circadian perturbations in Parkinson's disease. We also discuss the potential benefits of chronobiology-based personalized medicine in the management of Parkinson's disease both in terms of behavioural and pharmacological interventions. We propose that a fuller understanding of circadian clock function may shed important new light on the aetiology and symptomatology of the disease and may allow for improvements in the quality of life for the millions of people with Parkinson's disease.

Sleep Disturbances in Neurological Disease: A Target for Intervention

Sleep is a biological function required for neurological and general health, but a significant and under-recognized proportion of the population has disturbed sleep. Here, we briefly overview the biology of sleep, sleep requirements over the lifespan, and common sleep disorders. We then turn our attention to five neurological diseases that significantly contribute to global disease burden and neurology practice makeup: epilepsy, headache, ischemic stroke, Parkinson's disease, and Alzheimer's disease. For each disease, we review evidence that sleep disturbances contribute to disease risk and severity and discuss existing data that addressing sleep disturbances may have disease-modifying effects. We provide recommendations derived from the literature and existing clinical guidelines to facilitate the evaluation and management of sleep disturbances within the context of each neurological disease. Finally, we synthesize identified needs and commonalities into future directions for the field and practical sleep-related recommendations for physicians caring for patients at risk for or currently suffering from neurological disease.

Altered Motor Performance, Sleep EEG, and Parkinson's Disease Pathology Induced by Chronic Sleep Deprivation in Lrrk2G2019S Mice

Parkinson's disease (PD) is a multifaceted disease in which environmental variables combined with genetic predisposition cause dopaminergic (DAergic) neuron loss in the substantia nigra pars compacta. The mutation of leucine-rich repeat kinase 2 (Lrrk2) is the most common autosomal dominant mutation in PD, and it has also been reported in sporadic cases. A growing body of research suggests that circadian rhythm disruption, particularly sleep-wake abnormality, is common during the early phase of PD. Our present study aimed to evaluate the impact of sleep deprivation (SD) on motor ability, sleep performance, and PD pathologies in Lrrk2G2019S transgenic mice. After two months of SD, Lrrk2G2019S mice at 12 months of age showed an exacerbated PD-like phenotype with motor deficits, a reduced striatal DA level, degenerated DAergic neurons, and altered sleep structure and biological rhythm accompanied by the decreased protein expression level of circadian locomotor output cycles kaput Lrrk2 gene in the brain. All these changes persisted and were even more evident in 18-month-old mice after 6 months of follow-up. Moreover, a significant increase in α-synuclein aggregation was found in SD-treated transgenic mice at 18 months of age. Taken together, our findings indicate that sleep abnormalities, as a risk factor, may contribute to the pathogenesis and progression of PD. Early detection of sleep disorders and improvement of sleep quality may help to delay disease progression and provide long-term clinical benefits.

Modeling Parkinson's disease-related symptoms in alpha-synuclein overexpressing mice

BACKGROUND

Intracellular deposition of alpha-synuclein (α-syn) as Lewy bodies and Lewy neurites is a central event in the pathogenesis of Parkinson's disease (PD) and other α-synucleinopathies. Transgenic mouse models overexpressing human α-syn, are useful research tools in preclinical studies of pathogenetic mechanisms. Such mice develop α-syn inclusions as well as neurodegeneration with a topographical distribution that varies depending on the choice of promoter and which form of α-syn that is overexpressed. Moreover, they display motor symptoms and cognitive disturbances that to some extent resemble the human conditions.

PURPOSE

One of the main motives for assessing behavior in these mouse models is to evaluate the potential of new treatment strategies, including their impact on motor and cognitive symptoms. However, due to a high within-group variability with respect to such features, the behavioral studies need to be applied with caution. In this review, we discuss how to make appropriate choices in the experimental design and which tests that are most suitable for the evaluation of PD-related symptoms in such studies.

METHODS

We have evaluated published results on two selected transgenic mouse models overexpressing wild type (L61) and mutated (A30P) α-syn in the context of their validity and utility for different types of behavioral studies.

CONCLUSIONS

By applying appropriate behavioral tests, α-syn transgenic mouse models provide an appropriate experimental platform for studies of symptoms related to PD and other α-synucleinopathies.

The impact of probable rapid eye movement sleep behavior disorder on Parkinson's disease: A dual-tracer PET imaging study

OBJECTIVE

With a dual-tracer PET study design, this study aimed to identify the differences between PD patients with and without probable RBD (PD+RBD+/PD+RBD-) and the influence of timing of RBD onset [probable RBD anterior to PD onset (PD+RBDa)/probable RBD posterior to PD onset (PD+RBDp)].

METHODS

Seventy-four PD+RBD+ patients, sixty-three PD+RBD-patients and twenty healthy controls were enrolled. Clinical variates, striatal DAT tracer uptake, voxel-wise glucose metabolism and Parkinson's disease-related pattern (PDRP) expressions were compared among groups.

RESULTS

No significant difference were found on clinical characteristics between PD+RBD+ and PD+RBD-groups. Compared with PD+RBD-group, PD+RBD+ group had more severe dopaminergic dysfunction (p<0.05) except for posterior putamen in the more affected hemisphere (MAH) (p = 0.350). Meanwhile, it showed relative hypermetabolism in anterior putamen in the less affected hemisphere (LAH), bilateral anterior pallidum with wider involvement in the LAH, hippocampus and para-hippocampus in the LAH and bilateral olfactory gyrus, together with relative hypometabolism in limited bilateral posterio-parietal area (p<0.001). Significantly elevated PDRP expression was also seen in PD+RBD+ group (p < 0.01). For the timing of RBD onset, PD+RBDa patients harbored greater progression rate than PD+RBDp patients (p<0.01), greater DAT declining rates of striatal subregions and greater increasing rate of PDRP expressions than both PD+RBDp and PD+RBD-patients (p<0.05).

CONCLUSION

Our study found that PD patients with probable RBD have worse striatal dopaminergic dysfunction and higher PDRP network activity, supporting the assumption that PD with RBD may be a specific phenotype of PD. Additionally, RBD preceding PD onset may indicate a steeper disease decline.

Quantitative sensory testing and norepinephrine levels in REM sleep behaviour disorder - a clue to early peripheral autonomic and sensory dysfunction?

INTRODUCTION

Studies have reported autonomic impairment in patients with idiopathic REM sleep behaviour disorder (iRBD), which is considered a prodromal stage of alpha-synucleinopathies. It is still debated whether central or peripheral pathologies are first manifestations of alpha-synucleinopathies. This study aimed to characterize autonomic and somatosensory function in iRBD patients.

METHODS

This cross-sectional prospective case-control study included 17 iRBD patients (mean age 66.3 ± 9.2 years) and 16 healthy controls (HCs, 66.6 ± 11.3 years). Quantitative sensory testing, neurological and neuropsychological assessments, norepinephrine blood plasma levels, tilt table examination with orthostatic blood pressure, and heart rate variability were carried out. Longitudinal data of 10 iRBD patients, including neurological, neuropsychological, and tilt table examination, were assessed.

RESULTS

iRBD patients more frequently presented with orthostatic dysfunction than HCs (70.6% vs. 6.3%, p < 0.0001). Supine norepinephrine plasma levels were normal, but lower in iRBD (249.59 ± 99.78 pg/ml iRBD, 354.13 ± 116.38 pg/ml HCs, p < 0.05). Quantitative sensory testing revealed impaired cold (CDT) and vibration detection thresholds (VDT) on the foot in iRBD (CDT foot iRBD - 1.24 ± 0.31, HCs - 9.89E-17 ± 0.25, VDT iRBD - 1.11 ± 0.47, HCs - 1.46E-16 ± 0.25, p < 0.05). Cold detection thresholds differed between the foot and hand among iRBD patients (foot - 1.24 ± 0.31, hand - 0.56 ± 0.25, p < 0.05). Longitudinal data revealed an increase in maximum systolic and diastolic orthostatic blood pressure changes and a decrease in the Valsalva ratio in the follow-up group (p < 0.05).

CONCLUSION

This study revealed autonomic dysfunction with somatosensory impairment, and decreased norepinephrine levels in iRBD, which may serve as a possible prodromal marker for developing alpha-synucleinopathy.

Recent Progress in Non-motor Features of Parkinson's Disease with a Focus on Circadian Rhythm Dysregulation

Parkinson's disease (PD) is the second most common neurodegenerative disease, which manifests with both motor and non-motor symptoms. Circadian rhythm dysregulation, as one of the most challenging non-motor features of PD, usually appears long before obvious motor symptoms. Moreover, the dysregulated circadian rhythm has recently been reported to play pivotal roles in PD pathogenesis, and it has emerged as a hot topic in PD research. In this review, we briefly introduce the circadian rhythm and circadian rhythm-related genes, and then summarize recent research progress on the altered circadian rhythm in PD, ranging from clinical features to the possible causes of PD-related circadian disorders. We believe that future comprehensive studies on the topic may not only help us to explore the mechanisms of PD, but also shed light on the better management of PD.

Probable REM Sleep Behavior Disorder Is a Risk Factor for Symptom Progression in Parkinson Disease

Background: The literature is conflicting on whether rapid eye movement sleep behavior disorder (RBD) is associated with more rapid progression of Parkinson disease (PD).

Objective: We aimed to determine (1) how stable probable RBD (pRBD) is over time and (2) whether it predicts faster PD progression.

Methods: We evaluated participants in the Parkinson's Disease Biomarker Project (PDBP) who were prospectively assessed every 6–12 months with a series of motor, non-motor, disability, and health status scales. For aim 1, we calculated the incidence and disappearance rates of pRBD and compared stability of pRBD in PD with control subjects. For aim 2, we developed multiple regression models to determine if pRBD at baseline influenced the rate of change or average value at 48 months of 10 outcome variables.

Results: We found that pRBD was a less stable diagnosis for PD than controls. In pRBD+ subjects, the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score progressed 2.78 points per year faster (p < 0.01), MDS-UPDRS total score progressed 3.98 points per year faster (p < 0.01), a global composite outcome (GCO) worsened by 0.09 points per year faster (p = 0.02), and Parkinson's Disease Questionnaire (PDQ-39) mobility score progressed 2.57 percentage points per year faster (p < 0.01). The average scores at 48 months were 8.89 (p = 0.02) and 14.3 (p = 0.01) points higher for pRBD+ in MDS-UPDRS part III and total scores, respectively.

Conclusions: Our study confirms that pRBD detected at the start of a study portends more rapid progression of PD. Knowing this could be useful for enriching clinical trials with fast progressors to accelerate discovery of a disease modifying agent.

Impact of rapid eye movement sleep behavior disorder and autonomic disorders on Parkinson's disease: a review

Parkinson's disease (PD) has heterogeneous clinical manifestations and prognoses. It is accompanied by a group of motor and non-motor symptoms ranging from independence to total disability, limiting work and personal care activities. Currently, disease subtype markers for informing prognosis remain elusive. However, some studies have reported an association between rapid eye movement (REM) sleep behavior disorder (RBD) and faster motor and non-motor symptom progression, including autonomic dysfunction and cognitive decline. Moreover, since autonomic dysfunction has been described in idiopathic forms of RBD, and they share some central regulatory pathways, it remains unclear whether they have a primary association or if they are more severe in patients with PD and RBD, and thus are a disease subtype marker. This article aimed at critically reviewing the literature on the controversies about the prevalence of RBD in PD, the higher incidence of PD non-motor symptoms associated with RBD, the evidence of faster motor worsening in parkinsonian patients with this parasomnia, and the main pathophysiological hypotheses that support these findings.

Probable REM sleep behavior disorder is associated with longitudinal cortical thinning in Parkinson's disease

REM sleep behavior disorder (RBD) has a poor prognostic implication in both motor and non-motor functions in Parkinson’s disease (PD) patients. However, to the best of our knowledge no study to date investigated the longitudinal cerebral changes underlying RBD symptoms in PD. We performed the longitudinal study to investigate the association between probable RBD and cortical and subcortical changes in early, de novo PD patients. We studied 78 participants from the Parkinson’s Progression Marker Initiative who underwent structural MRI at baseline and after 2 years. The presence of probable RBD (pRBD) was evaluated using the RBD screening questionnaire. We compared the cross-sectional and longitudinal cortical thickness and subcortical volume changes, between PD patients with and without pRBD. At baseline, we found bilateral inferior temporal cortex thinning in the PD-pRBD group compared with the PD-noRBD group. Longitudinally, the PD-pRBD group revealed a significant increase in the rate of thinning in the left insula compared with the PD-noRBD group, and the increased thinning correlated with decreased cognitive performance. In subcortical volume analyses, the presence of pRBD was linked with volume decrease over time in the left caudate nucleus, pallidum and amygdala. The volume changes in the left caudate nucleus revealed correlations with global cognition. These results support the idea that RBD is an important marker of rapid progression in PD motor and non-motor symptoms and suggest that the atrophy in the left insula and caudate nucleus might be the underlying neurobiological mechanisms of the poorer prognosis in PD patients with RBD.

The Association Between REM Sleep Behavior Disorder and Autonomic Dysfunction in Parkinson's Disease

BACKGROUND

REM behavior disorder (RBD) can occur in the context of neurodegenerative alpha-synucleinopathies, such as Parkinson's disease (PD). PD patients with RBD (PD-pRBD) represent more severe symptoms and signs compared with those without RBD (PD-nRBD). On another note, autonomic dysfunction in PD patients is categorized as one of the most prominent non-motor symptoms and has been lately the field of interest in research.

OBJECTIVE

In the current study, we longitudinally studied autonomic dysfunction in PD-pRBD and PD-nRBD groups.

METHOD

This study was conducted on 420 drug-naïve PD patients selected from the Parkinson's Progression Markers Initiative database. The RBD Screening Questionnaire was used to define the presence of probable RBD. SCOPA-AUT was used to assess autonomic dysfunction. Additionally, dopamine transporter deficits on [123I] FP-CIT SPECT imaging was performed for all of the patients.

RESULTS

Out of 420 PD patients, 158 individuals (37.6%) were considered to have probable RBD (PD-pRBD) and others without RBD (PD-nRBD). Except for pupillomotor function, all the autonomic symptoms were significantly more severe in PD-pRBD group. In PD-nRBD group, caudate striatal binding ratio was negatively correlated with SCOPA-AUT scores, while no significant correlation was observed in PD-pRBD group. Finally, there was a significant difference considering the longitudinal changes of SCOPA-AUT total between PD-pRBD and PD-nRBD groups, suggesting a more severe autonomic decline in PD-pRBD patients.

CONCLUSION

Our results indicate that PD-pRBD patients have more severe autonomic dysfunction. These results support the theory that PD patients can be categorized based on the clinical presentation, possibly representing differences in the disease pathophysiology.

Spectrum of Non-Motor Symptoms in Parkinson's Disease

Parkinson's disease is predominantly classified as a movement disorder. Beyond the textbook definition of rigidity, tremors, and bradykinesia, Parkinson's disease encompasses an entire entity of non-motor symptom complexes that can precede the motor features by many years. Despite their significant clinical importance, the awareness of non-motor symptoms is quite negligible. Sleep disorders, gastrointestinal dysfunction, olfactory disturbances, anxiety, and depressive episodes are some of the most common non-motor presentations. The wide-spread occurrence of olfactory symptoms and the low cost of the assessment, is favoring olfactory dysfunction as a potential biomarker in Parkinson's. Sleep disorders may manifest before the motor and autonomic symptoms and might be linked to concomitant sleeping disorders like insomnia, REM sleep disorders, restless leg syndrome, narcolepsy, or obstructive sleep apnea. Non-motor symptoms can deteriorate the quality of life in Parkinson's patients. Early detection of non-motor symptoms can help in the diagnosis of Parkinson's disease and can fairly improve the survival and prognosis of these patients.

Cognitive and Neuropsychiatric Profiles in Idiopathic Rapid Eye Movement Sleep Behavior Disorder and Parkinson's Disease

Rapid eye movement (REM) sleep behavior disorder (RBD) is a risk factor for developing Parkinson’s disease (PD) and may represent its prodromal state. We compared neuropsychological and neuropsychiatric phenotypes of idiopathic (i) RBD, PD and healthy comparators (HC) in order to identify iRBD specific characteristics. Thirty-eight patients with iRBD, 38 PD patients with RBD (PD + RBD), 38 PD patients without RBD (PD-RBD) and 38 HC underwent a comprehensive neurological, neuropsychological and neuropsychiatric evaluation. iRBD, PD + RBD and PD-RBD performed worse than HC in short-term verbal memory, praxia, language and executive functions. iRBD had higher levels of anxiety, depression, apathy and alexithymia than HC. iRBD had higher levels of apathy than PD + RBD. Both PD groups had higher levels of anxiety and depression than HC. Surprisingly, iRBD performed better than all groups in long-term verbal memory. Patients diagnosed with iRBD are characterized by poor global cognitive performance, but better long-term memory and higher levels of depression, anxiety, alexithymia and apathy. Alexithymia and apathy in patients diagnosed with iRBD may be the expression of precocious derangement of emotional regulation, subsequently observed also in PD. Cognitive and neuropsychiatric symptoms of iRBD are early clinical manifestations of widespread neurodegeneration.

Improving Accuracy of Brainstem MRI Volumetry: Effects of Age and Sex, and Normalization Strategies

Background: Brainstem-mediated functions are impaired in neurodegenerative diseases and aging. Atrophy can be visualized by MRI. This study investigates extrinsic sources of brainstem volume variability, intrinsic sources of anatomical variability, and the influence of age and sex on the brainstem volumes in healthy subjects. We aimed to develop efficient normalization strategies to reduce the effects of intrinsic anatomic variability on brainstem volumetry.

Methods: Brainstem segmentation was performed from MPRAGE data using our deep-learning-based brainstem segmentation algorithm MD-GRU. The extrinsic variability of brainstem volume assessments across scanners and protocols was investigated in two groups comprising 11 (median age 33.3 years, 7 women) and 22 healthy subjects (median age 27.6 years, 50% women) scanned twice and compared using Dice scores. Intrinsic anatomical inter-individual variability and age and sex effects on brainstem volumes were assessed in segmentations of 110 healthy subjects (median age 30.9 years, range 18–72 years, 53.6% women) acquired on 1.5T (45%) and 3T (55%) scanners. The association between brainstem volumes and predefined anatomical covariates was studied using Pearson correlations. Anatomical variables with associations of |r| > 0.30 as well as the variables age and sex were used to construct normalization models using backward selection. The effect of the resulting normalization models was assessed by % relative standard deviation reduction and by comparing the inter-individual variability of the normalized brainstem volumes to the non-normalized values using paired t- tests with Bonferroni correction.

Results: The extrinsic variability of brainstem volumetry across different field strengths and imaging protocols was low (Dice scores > 0.94). Mean inter-individual variability/SD of total brainstem volumes was 9.8%/7.36. A normalization based on either total intracranial volume (TICV), TICV and age, or v-scale significantly reduced the inter-individual variability of total brainstem volumes compared to non-normalized volumes and similarly reduced the relative standard deviation by about 35%.

Conclusion: The extrinsic variability of the novel brainstem segmentation method MD-GRU across different scanners and imaging protocols is very low. Anatomic inter-individual variability of brainstem volumes is substantial. This study presents efficient normalization models for variability reduction in brainstem volumetry in healthy subjects.

The probable REM sleep behavior disorder negatively affects health-related quality of life in Parkinson's disease with bilateral subthalamic nucleus stimulation

OBJECTIVE

The aim of this study was to compare the short- and long-term outcomes of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) patients with and without probable REM sleep behavior disorder (RBD).

METHODS

We retrospectively reviewed 127 patients who underwent bilateral STN-DBS for PD with probable RBD from September 2011 to November 2018. Motor performance, physical and mental health-related quality of life (HRQoL), cognitive function, and depressive severity were compared between with or without probable RBD at the baseline and at the 1-, 3- or 5-year follow-up.

RESULTS

One hundred three PD patients (55 with RBD; 48 without RBD) were evaluated at the baseline and at the 1-year follow-up and 33 (17 with RBD, 16 without RBD) of them were examined at the 5-year follow-up. Motor performances were significantly improved in the non-RBD group compared to the RBD group at the 1-year follow-up, and there was a trend toward a greater difference in the physical HRQoL compared with the 1-year follow-up. There were also marked improvements of axial symptom and physical HRQoL in the non-RBD group compared with the RBD group from baseline to 5 years after STN-DBS.

CONCLUSION

Our study showed that RBD negatively affected the short- and long-term outcomes on motor performances, especially axial symptom and HRQoL after STN-DBS in PD patients.

REM sleep behavior disorder in early Parkinson's disease predicts the rapid dopaminergic denervation

OBJECTIVE

To test the hypothesis that REM sleep behavior disorder (RBD) in early Parkinson's disease (PD) predicts rapid progression of dopaminergic denervation.

METHODS

123I-FP-CIT single photon emission computed tomography (SPECT) scans were performed sequentially at baseline, 1 year, 2 years, and 4 years in 416 de novo patients with PD. RBD screening questionnaire scores >5 at baseline placed the participant in the likely-RBD group. Temporal changes in the specific binding ratio (SBR; caudate, putamen. sum of both, striatum) were compared between the likely-RBD and the non-likely-RBD groups for more or less affected striatum with a repeated measure ANOVA.

RESULTS

Likely-RBD was reported in 37.7% of the drug-naïve PD patients at baseline. The likely-RBD and non-likely-RBD groups did not have significant differences in the baseline clinical features including gender, age, disease duration, UPDRS motor score, and striatal SBR. Striatal SBR decreased significantly over four years in both groups (P < .001). In the analysis of a more affected striatum, striatal SBR decreased significantly faster in the likely-RBD group than in the non-likely-RBD group (P < .05 for all), whereas it was not statistically significant for the less affected striatum. The mean striatal SBR value (mean value of both striata), especially the caudate SBR, indicated greater acceleration of denervation in the likely-RBD group than in the non-likely-RBD group over time (P < .05).

CONCLUSION

Likely-RBD in PD predicts accelerating dopaminergic denervation, thereby implicating it as a marker for a poor prognosis or distinctive subtype in PD.

[Recommendations on performing polygraphy or polysomnography in the fields of psychiatry and psychotherapy : Position paper of the working group on sleep medicine of the German Association for Psychiatry, Psychotherapy and Psychosomatics]

Difficulties in falling asleep and maintaining sleep, nonrestorative sleep and decreased daytime wakefulness represent very common but relatively unspecific health complaints. Around 100 specific sleep-related disorders will be classified in their own major chap. 7 (sleep wake disorders) for the first time in the upcoming 11th version of the International Classification of Diseases (ICD 11). With respect to the disciplines of psychiatry and psychotherapy there is a bidirectional relationship between mental health and sleep wake disorders. Sleep wake disorders can be an independent risk factor for the onset of a mental disorder and have a negative influence on the course of the disease. In addition, sleep wake disorders can also precede a mental disease as an early symptom and therefore be an important indication for early recognition. Many sleep wake disorders can be diagnosed based on the anamnesis and routine clinical investigations. In special cases, examination in a specialized sleep laboratory and treatment in a sleep medicine center following a staged care approach can be mandatory. Polysomnography represents the gold standard for the differential diagnostics; however, there is no legal foundation in the field of neuropsychiatric disorders for remuneration in the German healthcare system. This review summarizes the current guidelines with respect to the criteria for an investigation in a sleep laboratory from the perspective of the disciplines of psychiatry and psychotherapy. From this the requirements for guideline-conform diagnostics and treatment are derived.

Brain atrophy in Parkinson's disease with polysomnography-confirmed REM sleep behavior disorder

We aimed to investigate cortical and subcortical brain alterations in people with Parkinson's disease with polysomnography-confirmed rapid eye movement (REM) sleep behavior disorder (RBD). Thirty people with Parkinson's disease, including 15 people with RBD, were recruited and compared with 41 healthy controls. Surface-based cortical and subcortical analyses were performed on T1-weighted images to investigate thickness and shape abnormalities between groups, and voxel-based and deformation-based morphometry were performed to investigate local volume. Correlations were performed in patients to investigate the structural correlates of motor activity during REM sleep. People with RBD showed cortical thinning in the right perisylvian and inferior temporal cortices and shape contraction in the putamen compared with people without RBD. Compared with controls, people with RBD had extensive cortical thinning and volume loss, brainstem volume was reduced, and shape contraction was found in the basal ganglia and hippocampus. In comparison to controls, people without RBD showed more restricted thinning in the sensorimotor, parietal, and occipital cortices, reduced volume in the brainstem, temporal and more posterior areas, and shape contraction in the pallidum and hippocampus. In Parkinson's disease, higher tonic and phasic REM sleep motor activity was associated with contraction of the thalamic surface, extensive cortical thinning, and subtle volume reduction in the middle temporal gyrus. In Parkinson's disease, the presence of RBD is associated with extensive cortical and subcortical abnormalities, suggesting more severe neurodegeneration in people with RBD. This provides potential neuroanatomical correlates for the more severe clinical phenotype reported in people with Parkinson's disease with RBD.

Tract-Based Spatial Statistics Reveal Lower White Matter Integrity Specific to Idiopathic Rapid Eye Movement Sleep Behavior Disorder as a Proxy for Prodromal Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is characterized by distinct motor symptoms which do not manifest until significant neurodegeneration has already occurred. Therefore, preventative treatments depend on PD being detected in a prodromal phase. To date, prodromal PD (pPD) has been conceptualized based on conditions such as REM Sleep Behavior Disorder (RBD), which has a high conversion rate to clinical PD (cPD). However, few studies have examined microstructural differences between healthy controls (HC), pPD, and cPD.

OBJECTIVE

The current study examined white matter microstructure in different phases of PD progression.

METHODS

Participants included 21 HC, 20 pPD (14 with RBD and 6 with hyposmia), and 17 cPD from the Parkinson's Progression Markers Initiative database. Tract-based spatial statistics were used to determine between group differences in fractional anisotropy (FA) and mean diffusivity (MD).

RESULTS

Mean diffusivity was significantly increased in pPD relative to cPD in widespread, but mostly right lateralized regions. Post-hoc analyses indicated that this pattern was particular to individuals with RBD. There were no microstructural differences between HC and pPD or cPD. The pPD group had significantly higher RBD symptoms and the cPD group had significantly higher motor symptoms.

CONCLUSIONS

Observed microstructural deterioration in individuals with RBD relative to cPD may indicate an altered pattern of neurodegeneration associated with RBD as a prodromal symptom of PD. Future studies should aim to further characterize possible differential patterns of progression from various non-motor symptoms (e.g., RBD, hyposmia) to cPD using longitudinal designs.

Overview of Sleep and Circadian Rhythm Disorders in Parkinson Disease

Sleep disorders are common among PD patients and affect quality of life. They are often under-recognized and under-treated. Mechanisms of sleep disorders in PD remain relatively poorly understood. Improved awareness of common sleep problems in PD. Tailored treatment and evidence for efficacy are lacking. The purpose of this review is to provide an overview and update on the most common sleep disorders in PD. We review specific features of the most common sleep disorders in PD, including insomnia, excessive daytime sleepiness, sleep-disordered breathing, restless legs syndrome, circadian rhythm disorders and REM sleep behavior disorders.

Deep Learning With EEG Spectrograms in Rapid Eye Movement Behavior Disorder

REM Behavior Disorder (RBD) is now recognized as the prodromal stage of α-synucleinopathies such as Parkinson's disease (PD). In this paper, we describe deep learning models for diagnosis/prognosis derived from a few minutes of eyes-closed resting electroencephalography data (EEG) collected at baseline from idiopathic RBD patients (n = 121) and healthy controls (HC, n = 91). A few years after the EEG acquisition (4±2 years), a subset of the RBD patients were eventually diagnosed with either PD (n = 14) or Dementia with Lewy bodies (DLB, n = 13), while the rest remained idiopathic RBD. We describe first a simple deep convolutional neural network (DCNN) with a five-layer architecture combining filtering and pooling, which we train using stacked multi-channel EEG spectrograms from idiopathic patients and healthy controls. We treat the data as in audio or image classification problems where deep networks have proven successful by exploiting invariances and compositional features in the data. For comparison, we study a simple deep recurrent neural network (RNN) model using three stacked Long Short Term Memory network (LSTM) cells or gated-recurrent unit (GRU) cells-with very similar results. The performance of these networks typically reaches 80% (±1%) classification accuracy in the balanced HC vs. PD-conversion classification problem. In particular, using data from the best single EEG channel, we obtain an area under the curve (AUC) of 87% (±1%)-while avoiding spectral feature selection. The trained classifier can also be used to generate synthetic spectrograms using the DeepDream algorithm to study what time-frequency features are relevant for classification. We find these to be bursts in the theta band together with a decrease of bursting in the alpha band in future RBD converters (i.e., converting to PD or DLB in the follow up) relative to HCs. From this first study, we conclude that deep networks may provide a useful tool for the analysis of EEG dynamics even from relatively small datasets, offering physiological insights and enabling the identification of clinically relevant biomarkers.

Accurate, rapid and reliable, fully automated MRI brainstem segmentation for application in multiple sclerosis and neurodegenerative diseases

Neurodegenerative disorders, such as Alzheimer's disease (AD) and progressive forms of multiple sclerosis (MS), can affect the brainstem and are associated with atrophy that can be visualized by MRI. Anatomically accurate, large-scale assessments of brainstem atrophy are challenging due to lack of automated, accurate segmentation methods. We present a novel method for brainstem volumetry using a fully-automated segmentation approach based on multi-dimensional gated recurrent units (MD-GRU), a deep learning based semantic segmentation approach employing a convolutional adaptation of gated recurrent units. The neural network was trained on 67 3D-high resolution T1-weighted MRI scans from MS patients and healthy controls (HC) and refined using segmentations of 20 independent MS patients' scans. Reproducibility was assessed in MR test-retest experiments in 33 HC. Accuracy and robustness were examined by Dice scores comparing MD-GRU to FreeSurfer and manual brainstem segmentations in independent MS and AD datasets. The mean %-change/SD between test-retest brainstem volumes were 0.45%/0.005 (MD-GRU), 0.95%/0.009 (FreeSurfer), 0.86%/0.007 (manually edited segmentations). Comparing MD-GRU to manually edited segmentations the mean Dice scores/SD were: 0.97/0.005 (brainstem), 0.95/0.013 (mesencephalon), 0.98/0.006 (pons), 0.95/0.015 (medulla oblongata). Compared to the manual gold standard, MD-GRU brainstem segmentations were more accurate than FreeSurfer segmentations (p < .001). In the multi-centric acquired AD data, the mean Dice score/SD for the MD-GRU-manual segmentation comparison was 0.97/0.006. The fully automated brainstem segmentation method MD-GRU provides accurate, highly reproducible, and robust segmentations in HC and patients with MS and AD in 200 s/scan on an Nvidia GeForce GTX 1080 GPU and shows potential for application in large and longitudinal datasets.

Automatic substantia nigra segmentation in neuromelanin-sensitive MRI by deep neural network in patients with prodromal and manifest synucleinopathy

Neuromelanin (NM) is a black pigment located in the brain in substantia nigra pars compacta (SN) and locus coeruleus. Its loss is directly connected to the loss of nerve cells in this part of the brain, which plays a role in Parkinson’s Disease. Magnetic resonance imaging (MRI) is an ideal tool to monitor the amount of NM in the brain in vivo. The aim of the study was the development of tools and methodology for the quantification of NM in a special neuromelanin-sensitive MRI images. The first approach was done by creating regions of interest, corresponding to the anatomical position of SN based on an anatomical atlas and determining signal intensity threshold. By linking the anatomical and signal intensity information, we were able to segment the SN. As a second approach, the neural network U-Net was used for the segmentation of SN. Subsequently, the volume characterizing the amount of NM in the SN region was calculated. To verify the method and the assumptions, data available from various patient groups were correlated. The main benefit of this approach is the observer-independency of quantification and facilitation of the image processing process and subsequent quantification compared to the manual approach. It is ideal for automatic processing many image sets in one batch.

Algorithmic Complexity of EEG for Prognosis of Neurodegeneration in Idiopathic Rapid Eye Movement Behavior Disorder (RBD)

Idiopathic rapid eye movement sleep behavior disorder (RBD) is a serious risk factor for neurodegenerative processes such as Parkinson's disease (PD). We investigate the use of EEG algorithmic complexity derived metrics for its prognosis. We analyzed resting state EEG data collected from 114 idiopathic RBD patients and 83 healthy controls in a longitudinal study forming a cohort in which several RBD patients developed PD or dementia with Lewy bodies. Multichannel data from ~ 3 min recordings was converted to spectrograms and their algorithmic complexity estimated using Lempel-Ziv-Welch compression. Complexity measures and entropy rate displayed statistically significant differences between groups. Results are compared to those using the ratio of slow to fast frequency power, which they are seen to complement by displaying increased sensitivity even when using a few EEG channels. Poor prognosis in RBD appears to be associated with decreased complexity of EEG spectrograms stemming in part from frequency power imbalances and cross-frequency amplitude algorithmic coupling. Algorithmic complexity metrics provide a robust, powerful and complementary way to quantify the dynamics of EEG signals in RBD with links to emerging theories of brain function stemming from algorithmic information theory.

Microstructural Changes in Patients With Parkinson's Disease Comorbid With REM Sleep Behaviour Disorder and Depressive Symptoms

The diagnosis of Parkinson's disease (PD) is currently anchored on clinical motor symptoms, which appear more than 20 years after initiation of the neurotoxicity. Extra-nigral involvement in the onset of PD with probable nonmotor manifestations before the development of motor signs, lead us to the preclinical (asymptomatic) or prodromal stages of the disease (various nonmotor or subtle motor signs). REM sleep behavior disorder (RBD) and depression are established prodromal clinical markers of PD and predict worse motor and cognitive outcomes. Nevertheless, taken by themselves, these markers are not yet claimed to be practical in identifying high-risk individuals. Combining promising markers may be helpful in a reliable diagnosis of early PD. Therefore, we aimed to detect neural correlates of RBD and depression in 93 treatment-naïve and non-demented early PD by means of diffusion MRI connectometry. Comparing four groups of PD patients with or without comorbid RBD and/or depressive symptoms with each other and with 31 healthy controls, we found that these two non-motor symptoms are associated with lower connectivity in several white matter tracts including the cerebellar peduncles, corpus callosum and long association fibers such as cingulum, fornix, and inferior longitudinal fasciculus. For the first time, we were able to detect the involvement of short association fibers (U-fibers) in PD neurodegenerative process. Longitudinal studies on larger sample groups are needed to further investigate the reported associations.

Prevalence and Clinical Characteristics of Probable REM Behavior Disorder in Thai Parkinson's Disease Patients

Background

Previous studies have shown that Parkinson's disease (PD) patients who have REM behavior disorder (PD with RBD) might be a PD subtype since they have different symptom clusters and disease trajectories from PD without RBD.

Objective

To study the prevalence of PD with pRBD and to compare the clinical characteristics with PD without pRBD. The feasibility of clinical interview of items adopted from the Mayo Sleep Questionnaire was also to be determined.

Methods

A total of 140 Parkinson's patients visiting neurological clinics during January to December 2016 were enrolled in this study. “Probable RBD (pRBD)” was defined as present when the patient answered “yes” to a question adapted from the first Mayo Sleep Questionnaire (MSQ). The demographic data, motor symptoms, and nonmotor symptoms were obtained.

Results

The prevalence of pRBD among this study's PD patients was 48.5% (68 out of the total of 140). The median onset of RBD before PD diagnosis was 5 years (range: 0–11 years). By comparison of PD with pRBD and PD without pRBD, this study showed significant difference in the levodopa equivalent dose (742 mg/day versus 566 mg/day; p < 0.01), prevalence of symptomatic orthostatic hypotension (35.3% versus 8.3%; p < 0.01). The multivariable analysis found that pRBD is independently associated with orthostatic hypotension (OR = 5.02, p < 0.01). Conclusion. The findings regarding prevalence and main clinical features of PD with pRBD in this study were similar to those of a previous study of PD with polysomnogram- (PSG-) proven RBD. This study hypothesized that interviewing by adopted MSQ may be a cost-effective tool for screening RBD. Further studies with direct comparison are needed.