Sleepiness and Unintended Sleep in Parkinson's Disease

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.

CLOCK 3111T/C Variant Correlates with Motor Fluctuation and Sleep Disorders in Chinese Patients with Parkinson's Disease

Background

The clock genes controlling biological rhythm play an important role in the pathophysiology of aging. The purpose of this study was to determine whether there is an association between a variant of the circadian locomotor output cycles kaput (CLOCK) gene and circadian dysfunction of Parkinson's disease (PD).

Methods

Six hundred and forty-six cases of Parkinson's disease from consecutive outpatients and inpatients ward from our hospital were included in this study. Kompetitive allele-specific PCR was used to determine the frequency distribution of genotypes and alleles. The examinations for the PD group were assessed in person in order to evaluate motor symptoms, cognitive function, sleep, and depression, including the Unified Parkinson's Disease Rating Scale (UPDRS), Mini-Mental State Examination (MMSE), Pittsburgh Sleep Quality Index (PSQI), and 17-item Hamilton Rating Scale for Depression (HAMD-17).

Results

Motor fluctuation (P < 0.001) and sleep disorders (P=0.007) were significantly different between the two groups. These correlations persisted after adjusting for confounding risk factors by further binary logistic regression analysis, suggesting that the CLOCK 3111T/C variant was associated with motor fluctuation (OR = 1.080, P < 0.001) and a subjective sleep disorder (OR = 1.130, P=0.037).

Conclusion

The CLOCK 3111T/C variant can be an independent risk factor for motor fluctuation and sleep disorder in Parkinson's disease.

Syndemics and the biosocial conception of health

The syndemics model of health focuses on the biosocial complex, which consists of interacting, co-present, or sequential diseases and the social and environmental factors that promote and enhance the negative effects of disease interaction. This emergent approach to health conception and clinical practice reconfigures conventional historical understanding of diseases as distinct entities in nature, separate from other diseases and independent of the social contexts in which they are found. Rather, all of these factors tend to interact synergistically in various and consequential ways, having a substantial impact on the health of individuals and whole populations. Specifically, a syndemics approach examines why certain diseases cluster (ie, multiple diseases affecting individuals and groups); the pathways through which they interact biologically in individuals and within populations, and thereby multiply their overall disease burden, and the ways in which social environments, especially conditions of social inequality and injustice, contribute to disease clustering and interaction as well as to vulnerability. In this Series, the contributions of the syndemics approach for understanding both interacting chronic diseases in social context, and the implications of a syndemics orientation to the issue of health rights, are examined.

Management of sleep disorders in Parkinson's disease and multiple system atrophy

Parkinson's disease (PD) and multiple system atrophy (MSA) are disorders associated with α synuclein-related neurodegeneration. Nonmotor symptoms are common hallmarks of these disorders, and disturbances of the sleep-wake cycle are among the most common nonmotor symptoms. It is only recently that sleep disturbances have received the attention of the medical and research community. Significant progress has been made in understanding the pathophysiology of sleep and wake disruption in alphasynucleinopathies during the past few decades. Despite these advancements, treatment options are limited and frequently associated with problematic side effects. Further studies that center on the development of novel treatment approaches are very much needed. In this article, the author discusses the current state of the management of disturbed sleep and alertness in PD and MSA. © 2017 International Parkinson and Movement Disorder Society.

Circadian system - A novel diagnostic and therapeutic target in Parkinson's disease?

The circadian system regulates biological rhythmicity in the human body. The role of the circadian system in neurological disorders is a theme that is attracting an increasing amount of interest from the scientific community. This has arisen, in part, from emerging evidence that disorders such as Parkinson's disease (PD) are multifactorial with many features exhibiting diurnal fluctuations, thereby suggestive of circadian involvement. Although the importance of fluctuating motor and nonmotor manifestations in PD have been well acknowledged, the role of the circadian system has received little attention until recently. It is proposed that intervening with circadian function provides a novel research avenue down which new strategies for improving symptomatic treatment and slowing of the progressive degenerative process can be approached to lessen the burden of PD. In this article we review the literature describing existing circadian research in PD and its experimental models.

Chronic sleep disturbance and neural injury: links to neurodegenerative disease

Sleep-wake disruption is frequently observed and often one of the earliest reported symptoms of many neurodegenerative disorders. This provides insight into the underlying pathophysiology of these disorders, as sleep-wake abnormalities are often accompanied by neurodegenerative or neurotransmitter changes. However, in addition to being a symptom of the underlying neurodegenerative condition, there is also emerging evidence that sleep disturbance itself may contribute to the development and facilitate the progression of several of these disorders. Due to its impact both as an early symptom and as a potential factor contributing to ongoing neurodegeneration, the sleep-wake cycle is an ideal target for further study for potential interventions not only to lessen the burden of these diseases but also to slow their progression. In this review, we will highlight the sleep phenotypes associated with some of the major neurodegenerative disorders, focusing on the circadian disruption associated with Alzheimer's disease, the rapid eye movement behavior disorder and sleep fragmentation associated with Parkinson's disease, and the insomnia and circadian dysregulation associated with Huntington's disease.

Consequences of Circadian Disruption on Neurologic Health

Circadian rhythms have a major role in physiology and behavior. Circadian disruption has negative consequences for physiologic homeostasis at molecular, cellular, organ-system, and whole-organism levels. The onset of many cerebrovascular insults shows circadian temporal trends. Impaired sleep-wake cycle, the most robust output rhythms of the circadian system, is significantly affected by neurodegenerative disorders, may precede them by decades, and may also affect their progression. Emerging evidence suggests that circadian disruption may be a risk factor for these neurologic disorders. This article discusses the implications of circadian rhythms in brain disorders, with an emphasis on cerebrovascular and neurodegenerative disorders.

Circadian melatonin rhythm and excessive daytime sleepiness in Parkinson disease

IMPORTANCE

Diurnal fluctuations of motor and nonmotor symptoms and a high prevalence of sleep-wake disturbances in Parkinson disease (PD) suggest a role of the circadian system in the modulation of these symptoms. However, surprisingly little is known regarding circadian function in PD and whether circadian dysfunction is involved in the development of sleep-wake disturbances in PD.

OBJECTIVE

To determine the relationship between the timing and amplitude of the 24-hour melatonin rhythm, a marker of endogenous circadian rhythmicity, with self-reported sleep quality, the severity of daytime sleepiness, and disease metrics.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional study from January 1, 2009, through December 31, 2012, of 20 patients with PD receiving stable dopaminergic therapy and 15 age-matched control participants. Both groups underwent blood sampling for the measurement of serum melatonin levels at 30-minute intervals for 24 hours under modified constant routine conditions at the Parkinson's Disease and Movement Disorders Center of Northwestern University.

INTERVENTIONS

Twenty-four hour monitoring of serum melatonin secretion.

MAIN OUTCOMES AND MEASURES

Clinical and demographic data, self-reported measures of sleep quality (Pittsburgh Sleep Quality Index) and daytime sleepiness (Epworth Sleepiness Scale), and circadian markers of the melatonin rhythm, including the amplitude, area under the curve (AUC), and phase of the 24-hour rhythm.

RESULTS

Patients with PD had blunted circadian rhythms of melatonin secretion compared with controls; the amplitude of the melatonin rhythm and the 24-hour AUC for circulating melatonin levels were significantly lower in PD patients (P < .001). Markers of the circadian phase were not significantly different between the 2 groups. Compared with PD patients without excessive daytime sleepiness, patients with excessive daytime sleepiness (Epworth Sleepiness Scale score ≥10) had a significantly lower amplitude of the melatonin rhythm and 24-hour melatonin AUC (P = .001). Disease duration, Unified Parkinson's Disease Rating Scale scores, levodopa equivalent dose, and global Pittsburgh Sleep Quality Index score in the PD group were not significantly related to measures of the melatonin circadian rhythm.

CONCLUSIONS AND RELEVANCE

Circadian dysfunction may underlie excessive sleepiness in PD. The nature of this association needs to be explored further in longitudinal studies. Approaches aimed to strengthen circadian function, such as timed exposure to bright light and exercise, might serve as complementary therapies for the nonmotor manifestations of PD.

Cerebrospinal hypocretin, daytime sleepiness and sleep architecture in Parkinson's disease dementia

Excessive daytime sleepiness is common in Parkinson's disease and has been associated with Parkinson's disease-related dementia. Narcoleptic features have been observed in Parkinson's disease patients with excessive daytime sleepiness and hypocretin cell loss has been found in the hypothalamus of Parkinson's disease patients, in association with advanced disease. However, studies on cerebrospinal fluid levels of hypocretin-1 (orexin A) in Parkinson's disease have been inconclusive. Reports of sleep studies in Parkinson's disease patients with and without excessive daytime sleepiness have also been disparate, pointing towards a variety of causes underlying excessive daytime sleepiness. In this study, we aimed to measure cerebrospinal fluid hypocretin-1 levels in Parkinson's disease patients with and without dementia and to study their relationship to dementia and clinical excessive daytime sleepiness, as well as to describe potentially related sleep architecture changes. Twenty-one Parkinson's disease patients without dementia and 20 Parkinson's disease patients with dementia, along with 22 control subjects without sleep complaints, were included. Both Epworth sleepiness scale, obtained with the help of the caregivers, and mini-mental state examination were recorded. Lumbar cerebrospinal fluid hypocretin-1 levels were measured in all individuals using a radio-immunoassay technique. Additionally, eight Parkinson's disease patients without dementia and seven Parkinson's disease patients with dementia underwent video-polysomnogram and multiple sleep latencies test. Epworth sleepiness scale scores were higher in Parkinson's disease patients without dementia and Parkinson's disease patients with dementia than controls (P < 0.01) and scores >10 were more frequent in Parkinson's disease patients with dementia than in Parkinson's disease patients without dementia (P = 0.04). Cerebrospinal fluid hypocretin-1 levels were similar among groups (controls = 321.15 +/- 47.15 pg/ml; without dementia = 300.99 +/- 58.68 pg/ml; with dementia = 309.94 +/- 65.95 pg/ml; P = 0.67), and unrelated to either epworth sleepiness scale or mini-mental state examination. Dominant occipital frequency awake was slower in Parkinson's disease patients with dementia than Parkinson's disease patients without dementia (P = 0.05). Presence of slow dominant occipital frequency and/or loss of normal non-rapid eye movement sleep architecture was more frequent among Parkinson's disease patients with dementia (P = 0.029). Thus, excessive daytime sleepiness is more frequent in Parkinson's disease patients with dementia than Parkinson's disease patients without dementia, but lumbar cerebrospinal fluid hypocretin-1 levels are normal and unrelated to severity of sleepiness or the cognitive status. Lumbar cerebrospinal fluid does not accurately reflect the hypocretin cell loss known to occur in the hypothalamus of advanced Parkinson's disease. Alternatively, mechanisms other than hypocretin cells dysfunction may be responsible for excessive daytime sleepiness and the sleep architecture alterations seen in these patients.

[Sleep in neurodegenerative disorders]

Neurodegenerative disorders are a group of heterogeneous, progressive disorders of varying etiology that affect one or more systems. They occur predominantly at older age, during which the structure and amount of sleep undergo changes. Neurodegenerative processes cause structural changes of the sleep/wake generators in the brainstem which result in disorders such as daytime sleepiness, insomnia, sleep-related movement and breathing disturbances, and disorders of the circadian rhythms. Some sleep disorders manifest years before the onset of neurodegenerative disorders and may serve as predictors. Polysomnography shows sleep fragmentation, tonic or phasic movements of the extremities, alteration of respiratory muscles, reduced slow wave sleep, REM sleep absence or without muscle atonia, increased arousal or wake activity, epileptiform EEG activity, and changes in sleep-related breathing. Very frequently, REM sleep behaviour disorder is associated with neurodegenerative disorders. In this overview we present symptoms, pathophysiology, and polysomnographic findings of sleep disorders in prevalent neurodegenerative disorders.

Sleep disorders in Parkinson's disease

Depression, dementia, and physiologic changes contribute to the high prevalence of sleep disturbances in patients with Parkinson's disease (PD). Antiparkinsonian drugs also play a role in insomnia by increasing daytime sleepiness and affecting motor symptoms and depression. Common types of sleep disturbances in PD patients include nocturnal sleep disruption and excessive daytime sleepiness, restless legs syndrome, rapid eye movement sleep behavior disorder, sleep apnea, sleep walking and sleep talking, nightmares, sleep terrors, and panic attacks. A thorough assessment should include complete medical and psychiatric histories, sleep history, and a 1- to 2-week sleep diary or Epworth Sleepiness Scale evaluation. Polysomnography or actigraphy may also be indicated. Treatment should address underlying factors such as depression or anxiety. Hypnotic therapy for sleep disturbances in PD patients should be approached with care because of the risks of falling, agitation, drowsiness, and hypotension. Behavioral interventions may also be useful.