The Treatment of Sleep Dysfunction in Neurodegenerative Disorders

Assessment of sleep patterns in dementia and general population cohorts using passive in-home monitoring technologies

BACKGROUND

Nocturnal disturbances are a common symptom experienced by People Living with Dementia (PLWD), and these often present prior to diagnosis. Whilst sleep anomalies have been frequently reported, most studies have been conducted in lab environments, which are expensive, invasive and not natural sleeping environments. In this study, we investigate the use of in-home nocturnal monitoring technologies, which enable passive data collection, at low cost, in real-world environments, and without requiring a change in routine.

METHODS

Clustering analysis of passively collected sleep data in the natural sleep environment can help identify distinct sub-groups based on sleep patterns. The analysis uses sleep activity data from; (1) the Minder study, collecting in-home data from PLWD and (2) a general population dataset (combined n = 100, >9500 person-nights).

RESULTS

Unsupervised clustering and profiling analysis identifies three distinct clusters. One cluster is predominantly PLWD relative to the two other groups (72% ± 3.22, p = 6.4 × 10-7, p = 1.2 × 10-2) and has the highest mean age (77.96 ± 0.93, p = 6.8 × 10-4 and p = 6.4 × 10-7). This cluster is defined by increases in light and wake after sleep onset (p = 1.5 × 10-22, p = 1.4 × 10-7 and p = 1.7 × 10-22, p = 1.4 × 10-23) and decreases in rapid eye movement (p = 5.5 × 10-12, p = 5.9 × 10-7) and non-rapid eye movement sleep duration (p = 1.7 × 10-4, p = 3.8 × 10-11), in comparison to the general population.

CONCLUSIONS

In line with current clinical knowledge, these results suggest detectable dementia sleep phenotypes, highlighting the potential for using passive digital technologies in PLWD, and for  detecting architectural sleep changes more generally. This study indicates the feasibility of leveraging passive in-home technologies for disease monitoring.

Knowledge Structure and Emerging Trends of Mild Cognitive Impairment with Dyssomnias in Recent 20 Years: A Bibliometric Analysis via CiteSpace and VOSviewer

Background

Mild cognitive impairment (MCI), an intermediate stage between normal aging and dementia, has emerged as a prominent research area in geriatric care due to its heightened propensity for progressing toward dementia. Sleep plays a pivotal role in cognitive function, with dyssomnias not only exacerbating cognitive and affective symptoms associated with neurodegenerative diseases but also contributing to disease progression.

Aim

This bibliometric analysis investigates the global research on MCI with dyssomnias over the past two decades, aiming to discern key findings, research domains, and emerging trends in this field.

Methods

In this study, a bibliometric analysis was conducted using the search terms "MCI" and "sleep". Data were extracted from the Web of Science Core Collection database, and visualization and collaborative analysis were performed using CiteSpace and VOSviewer.

Results

This study encompassed 546 publications from 2003 to 2023. The publication volume and citation rate consistently increased over time. Neurosciences, Clinical Neurology, and Geriatrics Gerontology emerged as the top three research fields. The Journal of Alzheimer's Disease had the highest publication count, while Sleep Medicine received the most citations. USA, China, and Italy led in publication output. Collaborative clusters among authors and institutions were identified, but cooperation between clusters was limited. Active cocited reference clusters included "obstructive sleep apnea", "possible mediating pathways", and "isolated rapid eye movement sleep behaviour disorder". The top frequently mentioned keywords, besides "MCI", were "Alzheimer's disease", "dementia", "risk factor", and "Parkinson's Disease". Notable keyword clusters spanned circadian rhythm, Parkinson's disease, MCI, dementia with Lewy body, subjective cognitive impairment, Lewy body disease, Alzheimer's disease, and dietary patterns.

Conclusion

The field of MCI with dyssomnias is rapidly expanding, encompassing a wide range of neurodegenerative disorders and sleep disturbances. Current research endeavors are primarily focused on elucidating the underlying pathogenesis, predicting disease progression, and developing innovative treatment strategies for individuals affected by MCI with dyssomnias.

The administration of rhBmal1 reduces sleep deprivation-induced anxiety and cognitive impairment in mice

BACKGROUND

In mammals, circadian rhythms control metabolism, immunological response and reproductive processes. Bmal1 (brain and muscle Arnt-like protein-1) is a key element in the regulation of circadian rhythms.

METHODS

This investigation explores the pathophysiological effects of sleep deprivation in a mouse model as well as the potential underlying mechanisms. A mouse sleep deprivation model was constructed using a modified multi-platform water environment method. The anxiety-like behaviours of mice were assessed by the open field test and elevated plus maze, and the cognitive function of mice was tested by the nest-building test. The expression levels of targeted genes were determined by Western blotting assay and RT-qPCR assay.

RESULTS

We found that sleep deprivation profoundly enhanced anxiety levels and impaired cognitive function in mice. Sleep deprivation also reduced the expression levels of Bmal1 and BDNF (brain-derived neurotrophic factor) and increased oxidative stress in the hippocampus of mice. The intraperitoneal injection of human recombinant rhBmal1 protein alleviated sleep deprivation-induced anxiety and cognitive impairment, restored Bmal1 and BDNF levels, and reduced oxidative stress in the hippocampus of mice.

CONCLUSIONS

rhBmal1 treatment might serve as a potential therapy for mitigating sleep deprivation-related unfavourable symptoms.

Neuroprotective Potential of Melatonin: Evaluating Therapeutic Efficacy in Alzheimer's and Parkinson's Diseases

Decreased melatonin levels have been linked to both Alzheimer's disease (AD) and Parkinson's disease (PD), which are the two most prevalent neurodegenerative disorders. The development of sleep disorders is widespread in patients diagnosed with AD or PD. In this regard, calcification of the pineal gland, typically seen in the third decade, has been associated with a reduction in melatonin production. Recent studies have suggested that exogenous melatonin application can be utilized to treat sleep disorders in patients with neurodegenerative diseases. Furthermore, research has shown that deficiencies in melatonin levels in patients with AD or PD begin before a diagnosis of either disease is made. These findings could encourage further research on melatonin as a potential biomarker for the diagnosis or a possible area for the early treatment of these diseases. Many clinical studies have also produced data denoting melatonin treatment as a method to reduce the detrimental neurocognitive effects of these diseases. Further research on the role of melatonin in neurodegenerative diseases could expand symptomatic and prophylactic treatment options for diseases such as AD and PD. This review investigates melatonin's physiological properties, its role in AD and PD, and current findings on its potential therapeutic benefits in AD and PD patients.

The state of brain activity modulates cerebrospinal fluid transport

Earlier studies based on 2-photon imaging have shown that glymphatic cerebrospinal fluid (CSF) transport is regulated by the sleep-wake cycle. To examine this association, we used 3DISCO whole-body tissue clearing to map CSF tracer distribution in awake, sleeping and ketamine-xylazine anesthetized mice. The results of our analysis showed that CSF tracers entered the brain to a significantly larger extent in natural sleep or ketamine-xylazine anesthesia than in wakefulness. Furthermore, awake mice showed preferential transport of CSF tracers in the rostro-caudal direction towards the cervical and spinal cord lymphatic vessels, and hence to venous circulation and excretion by the kidneys. The study extends the current literature by showing that CSF dynamics on the whole-body scale is controlled by the state of brain activity.

Pharmacological interventions targeting α-synuclein aggregation triggered REM sleep behavior disorder and early development of Parkinson's disease

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by elevated motor behaviors and dream enactments in REM sleep, often preceding the diagnosis of Parkinson's disease (PD). As RBD could serve as a biomarker for early PD developments, pharmacological interventions targeting α-synuclein aggregation triggered RBD could be applied toward early PD progression. However, robust therapeutic guidelines toward PD-induced RBD are lacking, owing in part to a historical paucity of effective treatments and trials. We reviewed the bidirectional links between α-synuclein neurodegeneration, progressive sleep disorders, and RBD. We highlighted the correlation between RBD development, α-synuclein aggregation, and neuronal apoptosis in key brainstem regions involved in REM sleep atonia maintenance. The current pharmacological intervention strategies targeting RBD and their effects on progressive PD are discussed, as well as current treatments for progressive neurodegeneration and their effects on RBD. We also evaluated emerging and potential pharmacological solutions to sleep disorders and developing synucleinopathies. This review provides insights into the mechanisms and therapeutic targets underlying RBD and PD, and explores bidirectional treatment effects for both diseases, underscoring the need for further research in this area.

Sex differences in the effects of sleep disorders on cognitive dysfunction

Sleep is an essential physiological function that sustains human life. Sleep disorders involve problems with the quality, duration, and abnormal behaviour of sleep. Insomnia is the most common sleep disorder, followed by sleep-disordered breathing (SDB). Sleep disorders often occur along with medical conditions or other mental health conditions. Of particular interest to researchers is the role of sleep disorders in cognitive dysfunction. Sleep disorder is a risk factor for cognitive dysfunction, yet the exact pathogenesis is still far from agreement. Little is known about how sex differences influence the changes in cognitive functions caused by sleep disorders. This narrative review examines how sleep disorders might affect cognitive impairment, and then explores the sex-specific consequences of sleep disorders as a risk factor for dementia and the potential underlying mechanisms. Some insights on the direction of further research are also presented.

Neuroprotective Effect of Melatonin on Sleep Disorders Associated with Parkinson's Disease

Parkinson's disease (PD) is a complex, multisystem disorder with both neurologic and systemic manifestations, which is usually associated with non-motor symptoms, including sleep disorders. Such associated sleep disorders are commonly observed as REM sleep behavior disorder, insomnia, sleep-related breathing disorders, excessive daytime sleepiness, restless legs syndrome and periodic limb movements. Melatonin has a wide range of regulatory effects, such as synchronizing circadian rhythm, and is expected to be a potential new circadian treatment of sleep disorders in PD patients. In fact, ongoing clinical trials with melatonin in PD highlight melatonin's therapeutic effects in this disease. Mechanistically, melatonin plays its antioxidant, anti-inflammatory, anti-excitotoxity, anti-synaptic dysfunction and anti-apoptotic activities. In addition, melatonin attenuates the effects of genetic variation in the clock genes of Baml1 and Per1 to restore the circadian rhythm. Together, melatonin exerts various therapeutic effects in PD but their specific mechanisms require further investigations.

Sleep and Circadian Rhythm Dysfunction in Animal Models of Huntington's Disease

Sleep and circadian disruption affects most individuals with Huntington's disease (HD) at some stage in their lives. Sleep and circadian dysregulation are also present in many mouse and the sheep models of HD. Here I review evidence for sleep and/or circadian dysfunction in HD transgenic animal models and discuss two key questions: 1) How relevant are such findings to people with HD, and 2) Whether or not therapeutic interventions that ameliorate deficits in animal models of HD might translate to meaningful therapies for people with HD.

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.

Modelling Neurological Diseases in Large Animals: Criteria for Model Selection and Clinical Assessment

Issue: The impact of neurological disorders is recognised globally, with one in six people affected in their lifetime and few treatments to slow or halt disease progression. This is due in part to the increasing ageing population, and is confounded by the high failure rate of translation from rodent-derived therapeutics to clinically effective human neurological interventions. Improved translation is demonstrated using higher order mammals with more complex/comparable neuroanatomy. These animals effectually span this translational disparity and increase confidence in factors including routes of administration/dosing and ability to scale, such that potential therapeutics will have successful outcomes when moving to patients. Coupled with advancements in genetic engineering to produce genetically tailored models, livestock are increasingly being used to bridge this translational gap. Approach: In order to aid in standardising characterisation of such models, we provide comprehensive neurological assessment protocols designed to inform on neuroanatomical dysfunction and/or lesion(s) for large animal species. We also describe the applicability of these exams in different large animals to help provide a better understanding of the practicalities of cross species neurological disease modelling. Recommendation: We would encourage the use of these assessments as a reference framework to help standardise neurological clinical scoring of large animal models.

Hypnotic enhancement of slow-wave sleep increases sleep-associated hormone secretion and reduces sympathetic predominance in healthy humans

Sleep is important for normal brain and body functioning, and for this, slow-wave sleep (SWS), the deepest stage of sleep, is assumed to be especially relevant. Previous studies employing methods to enhance SWS have focused on central nervous components of this sleep stage. However, SWS is also characterized by specific changes in the body periphery, which are essential mediators of the health-benefitting effects of sleep. Here we show that enhancing SWS in healthy humans using hypnotic suggestions profoundly affects the two major systems linking the brain with peripheral body functions, i.e., the endocrine and the autonomic nervous systems (ANS). Specifically, hypnotic suggestions presented at the beginning of a 90-min afternoon nap to promote subsequent SWS strongly increased the release of growth hormone (GH) and, to a lesser extent, of prolactin and aldosterone, and shifted the sympathovagal balance towards reduced sympathetic predominance. Thus, the hypnotic suggestions induced a whole-body pattern characteristic of natural SWS. Given that the affected parameters regulate fundamental physiological functions like metabolism, cardiovascular activity, and immunity, our findings open up a wide range of potential applications of hypnotic SWS enhancement, in addition to advancing our knowledge on the physiology of human SWS.

The hypnotic enhancement of slow wave sleep, the deepest stage of sleep, goes beyond the central nervous system, causing changes at the level of the endocrine and the autonomic nervous systems.

Cross talk mechanism of disturbed sleep patterns in neurological and psychological disorders

The incidence and prevalence of sleep disorders continue to increase in the elderly populace, particularly those suffering from neurodegenerative and neuropsychiatric disorders. This not only affects the quality of life but also accelerates the progression of the disease. There are many reasons behind sleep disturbances in such patients, for instance, medication use, nocturia, obesity, environmental factors, nocturnal motor disturbances and depressive symptoms. This review focuses on the mechanism and effects of sleep dysfunction in neurodegenerative and neuropsychiatric disorders. Wherein we discuss disturbed circadian rhythm, signaling cascade and regulation of genes during sleep deprivation. Moreover, we explain the perturbation in brainwaves during disturbed sleep and the ocular perspective of neurodegenerative and neuropsychiatric manifestations in sleep disorders. Further, as the pharmacological approach is often futile and carries side effects, therefore, the non-pharmacological approach opens newer possibilities to treat these disorders and widens the landscape of treatment options for patients.

Alzheimer's disease and sleep disorders: Insights into the possible disease connections and the potential therapeutic targets

One of the comorbid conditions in an individual with Alzheimer's disease is a sleep disorder. Clinical features of sleep disorders involve various sleep disturbances such as Obstructive Sleep Apnea (OSAS), Excessive Daytime Sleepiness (EDS), Rapid Eye Movement (REM), Breathing Disorders, Periodic limb movements in sleep (PLMS), etc. The primary tools used for the identification of such disturbances are Polysomnography (PSG) and Wrist actigraphy. This review will highlight and explains the different approaches used in the treatment of sleep disorders. Non-pharmacological treatments include Peter Hauri rules, sleep education program, and light therapy which play a key role in the regulation of sleep-wake cycles. Pharmacological therapy described in this article may be useful in treating sleep destruction in patients with Alzheimer's disease. Along with the Non-pharmacological and pharmacological treatment, here we discuss five commonly recognized plant-based nutraceuticals with hypothesized impact on sleep disorders: caffeine, chamomile, cherries, L-tryptophan, and valerian by the proper emphasis on the known mechanism of their action.

What evidence is there for implicating the brain orexin system in neuropsychiatric symptoms in dementia?

Neuropsychiatric symptoms (NPS) affect people with dementia (PwD) almost universally across all stages of the disease, and regardless of its exact etiology. NPS lead to disability and reduced quality of life of PwD and their caregivers. NPS include hyperactivity (agitation and irritability), affective problems (anxiety and depression), psychosis (delusions and hallucinations), apathy, and sleep disturbances. Preclinical studies have shown that the orexin neuropeptide system modulates arousal and a wide range of behaviors via a network of axons projecting from the hypothalamus throughout almost the entire brain to multiple, even distant, regions. Orexin neurons integrate different types of incoming information (e.g., metabolic, circadian, sensory, emotional) and convert them into the required behavioral output coupled to the necessary arousal status. Here we present an overview of the behavioral domains influenced by the orexin system that may be relevant for the expression of some critical NPS in PwD. We also hypothesize on the potential effects of pharmacological interference with the orexin system in the context of NPS in PwD.

Sleep-Based Interventions in Alzheimer's Disease: Promising Approaches from Prevention to Treatment along the Disease Trajectory

The multifactorial nature of Alzheimer’s disease (AD) has led scientific researchers to focus on the modifiable and treatable risk factors of AD. Sleep fits into this context, given the bidirectional relationship with AD confirmed by several studies over the last years. Sleep disorders appear at an early stage of AD and continue throughout the entire course of the pathology. Specifically, sleep abnormalities, such as more fragmented sleep, increase in time of awakenings, worsening of sleep quality and primary sleep disorders raise with the severity and progression of AD. Intervening on sleep, therefore, means acting both with prevention strategies in the pre-clinical phase and with treatments during the course of the disease. This review explores sleep disturbances in the different stages of AD, starting from the pre-clinical stage. Particular attention is given to the empirical evidence investigating obstructive sleep apnea (OSA) disorder and the mechanisms overlapping and sharing with AD. Next, we discuss sleep-based intervention strategies in the healthy elderly population, mild cognitive impairment (MCI) and AD patients. We mention interventions related to behavioral strategies, combination therapies, and bright light therapy, leaving extensive space for new and raising evidence on continuous positive air pressure (CPAP) treatment effectiveness. Finally, we clarify the role of NREM sleep across the AD trajectory and consider the most recent studies based on the promising results of NREM sleep enhancement, which use innovative experimental designs and techniques.

Sleep Neurology's Toolkit at the Crossroads: Challenges and Opportunities in Neurotherapeutics Lost and Found in Translation

We find ourselves at our present crossroads with a well-traveled toolkit, perhaps too well worn but with aspirational hopes and dreams for the field of sleep neurotherapeutics. This volume is organized thematically into six topical domains that parallel the major subspecialty areas of contemporary clinical sleep neurology practice, as well as novel directions and opportunities. The issue begins with an overview of the central disorders of hypersomnolence, including narcolepsy, idiopathic hypersomnia and other hypersomnia disorders, and the related use of the entire broad range of stimulant and wake-promoting pharmacotherapies. Next, the range of behavioral therapies, application of light and light restriction and melatonin therapies, and hypnotic pharmacotherapies useful in insomnia and circadian sleep-wake rhythm disorders are reviewed, followed by an overview of treatment options for sleep-related breathing disorders including positive airway pressure and the novel approach of hypoglossal neurostimulation for obstructive sleep apnea. The parasomnias and sleep-related movement disorders, including NREM disorders of arousal, REM parasomnias (nightmares and isolated sleep paralysis and idiopathic/isolated REM sleep behavior disorder, and restless legs syndrome are then discussed, and the applications of sleep neurotherapeutics in sleep and neurological disease are reviewed, including neurodevelopmental, epileptic, autoimmune encephalopathies, and neurodegenerative diseases. Last, the novel directions and opportunities in sleep neurology offered by cannabinoid therapies and machine learning/artificial intelligence methodology conclude this comprehensive survey of contemporary sleep neurology. We hope that you find this volume to be a useful and inspirational support tool for the work that matters most, your care of all our sleep neurology patients in the clinics.

Pharmacological and Non-pharmacological Treatments of Sleep Disorders in Parkinson's Disease

Sleep disorders are one of the most common non-motor symptoms in Parkinson's disease (PD). It can cause a notable decrease in quality of life and functioning in PD patients, as well as place a huge burden on both patients and caregivers. The most cited sleep disorders in PD included insomnia, restless legs syndrome (RLS), rapid eye movement (REM), sleep behavior disorders (RBD), excessive daytime sleepiness (EDS) and sleep disordered breathing (SDB), which can appear alone or several at the same time. In this review, we listed the recommended pharmacological treatments for common sleep disorders in PD, and discussed the recommended dosages, benefits and side effects of relative drugs. We also discussed non-pharmacological treatments to improve sleep quality, including sleep hygiene education, exercise, deep brain stimulation, cognitive behavior therapy and complementary therapies. We tried to find proper interventions for different types of sleep disorders in PD, while minimizing relative side effects.