Melatonin for sleep disturbances in Parkinson's disease

Dietary Protocols to Promote and Improve Restful Sleep: A Narrative Review

Humans spend approximately one third of their life asleep but, as counterintuitive as it may sound, sleep is far from being a quiet state of inactivity. Sleep provides the opportunity to perform numerous biological and physiological functions that are essential to health and wellbeing, including memory consolidation, physical recovery, immunoregulation, and emotional processing. Yet, sleep deprivation, chronic sleep restriction, and various types of sleep disorders are all too common in modern society. Failure to meet the recommended 7-9 hours of restful sleep per night is known to increase the risk of several health conditions, reason why regular and adequate sleep should be seen as a priority instead of an unnecessary commodity easily traded as required by the commitments of our busy lives. While both the quantity and the quality of sleep can be largely improved with relatively straightforward practices dictated by good sleep hygiene, emerging research suggests that dietary and supplementation protocols focused on certain foods, nutrients, and biochemical compounds with sleep-promoting properties can act as subsidiary sleep aids in complementing these behavioral changes. The scope of this narrative review is to summarize the available evidence on the potential benefits of selected nutraceuticals in the context of circadian rhythm and sleep disturbances, namely melatonin, magnesium, omega-3 fatty acids, tart cherry juice, kiwifruit, apigenin, valerian root, L-theanine, glycine, ashwagandha, myoinositol, Rhodiola rosea, and phosphatidylserine. A comprehensive recapitulation of the relevant literature is provided, alongside corresponding evidence-based nutritional protocols to promote and improve restful sleep.

Exploring the role of melatonin in managing sleep and motor symptoms in Parkinson's disease: a pooled analysis of double-blinded randomized controlled trials

BACKGROUND

Parkinson's disease (PD), a progressive neurodegenerative disorder, often involves sleep disturbances, affecting 88-98% of patients. Melatonin, a sleep-regulating neurohormone, shows the potential to improve sleep quality and non-motor symptoms in PD.

AIM

To evaluate melatonin's efficacy and safety in PD patients with sleep disorders.

METHODS

We systematically searched PubMed, Scopus, Web of Science, and Cochrane till January 2025. The risk of bias in the included studies was evaluated using the Cochrane risk-of-bias tool. Dichotomous outcomes were expressed as risk ratios (RRs) with 95% confidence intervals (CIs), while continuous outcomes were reported as mean differences (MDs) with 95% CIs.

RESULTS

We retrieved 2537 records. Five double-blinded RCTs were finally included. The meta-analysis revealed a significant improvement in sleep quality, as measured by the Pittsburgh Sleep Quality Index (PSQI), in the melatonin group compared to placebo (MD= -1.88, 95% CI: [-3.07, -0.68], P = 0.002). However, no significant differences were observed for the Epworth Sleepiness Scale (MD= -1.04 CI: [-2.81, 0.73], P = 0.25), total sleep time (MD = 14.85 min CI: [-5.45, 35.16], P = 0.15), sleep efficiency, sleep latency, REM sleep latency, frequency of arousals, or REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ; MD = 0.74, P = 0.50). For Parkinson's disease-related outcomes, melatonin significantly improved Non-Motor Symptom Scale (NMSS) scores but showed no significant effects on UPDRS Part III scores or Parkinson's Disease Quality of Life.

CONCLUSION

Melatonin improves subjective sleep quality and non-motor symptoms in PD patients with a favorable safety profile, but effects on objective measures and motor symptoms remain inconclusive.

TRIAL REGISTRY NUMBER

This meta-analysis was registered on PROSPERO.

REGISTRATION NUMBER

CRD42024619496.

Melatonin for Huntington's Disease (HD) gene carriers with HD-related sleep disturbance - A pilot study

BACKGROUND

Sleep disorders are common in people with Huntington's Disease (HD). Possible causes include disruptions to the body's internal clock and changes in melatonin levels. Although melatonin is known to treat sleep disruptions related to circadian rhythm disorders, its effects on HD patients have not been thoroughly explored.

OBJECTIVE

to assess the effectiveness of melatonin in improving the sleep quality of individuals with HD.

METHODS

double-blind, randomized, placebo-controlled, crossover trial with individuals with HD experiencing sleep disturbances, defined as Pittsburgh Sleep Quality Index (PSQI) > 5. Participants received 4-week treatments with 5 mg immediate-release melatonin/placebo, separated by a one-week wash-out (NCT04421339). Clinical assessments were conducted at baseline, week 5 (crossover visit), and week 9 (final visit) and included the PSQI, HD Sleep Questionnaire (HD-SQ), Epworth Sleepiness Scale (ESS), Montreal Cognitive Assessment (MoCA), Neuro-QoL™ v2.0 Cognitive Function, Neuropsychiatric Inventory Questionnaire (NPI-Q), Hospital Anxiety and Depression Scale (HADS), Unified Huntington Disease Rating Scale (UHDRS), and Clinical Global Impression (CGI).

RESULTS

Fifteen patients (46.53 ± 13.92 years old, seven females) completed the study procedures. We found no significant differences between melatonin and placebo treatments in the primary outcome (PSQI), other sleep measures (ESS and HD-SQ), neuropsychiatric symptoms (NPI-Q, HADS, Neuro-QoL, MoCA), and motor/functional measures.

CONCLUSIONS

We found that melatonin did not significantly differ from placebo in improving sleep quality in individuals with HD. Given the conflicting findings from previous research, it may be beneficial to explore alternative dosages of melatonin, increase the sample size, and consider different stages of HD in future studies.

Circadian clock communication during homeostasis and ageing

Maintaining homeostasis is essential for continued health, and the progressive decay of homeostatic processes is a hallmark of ageing. Daily environmental rhythms threaten homeostasis, and circadian clocks have evolved to execute physiological processes in a manner that anticipates, and thus mitigates, their effects on the organism. Clocks are active in almost all cell types; their rhythmicity and functional output are determined by a combination of tissue-intrinsic and systemic inputs. Numerous inputs for a specific tissue are produced by the activity of circadian clocks of other tissues or cell types, generating a form of crosstalk known as clock communication. In mammals, the central clock in the hypothalamus integrates signals from external light-dark cycles to align peripheral clocks elsewhere in the body. This regulation is complemented by a tissue-specific milieu of external, systemic and niche inputs that modulate and cooperate with the cellular circadian clock machinery of a tissue to tailor its functional output. These mechanisms of clock communication decay during ageing, and growing evidence suggests that this decline might drive ageing-related morbidities. Dietary, behavioural and pharmacological interventions may offer the possibility to overcome these changes and in turn improve healthspan.

Sleep and circadian dysfunction in Parkinson disease: New perspective and opportunities for treatment

Sleep and circadian dysfunction are common nonmotor symptoms in patients with Parkinson disease (PD). Sleep and circadian dysfunction usually have a significant negative impact on quality of life and may also serve as markers to identify patients in the preclinical stage of PD. Sleep disturbances have different types in PD such as insomnia, excessive daytime sleepiness, rapid eye movement sleep behavior disorders, restless legs syndrome, and sleep-disordered breathing. Because PD has a variety of clinical manifestations, sleep disorders and circadian dysfunction are most easy to be overlooked. The management of sleep and circadian dysfunction in patients with PD is complex as these conditions are heterogeneous; therefore, treatment plans must be individualized and directed at the underlying cause(s). Therefore, screening for and managing sleep and circadian dysfunction are important in clinical practice, and looking for new perspective and opportunities for treatment of them may improve the quality of life of PD patients. Therefore, screening for and managing sleep and circadian dysfunction are important in clinical practice. Looking for new perspective and opportunities for treatment will likely improve the quality of life of PD patients.

Melatonin, an Antitumor Necrosis Factor Therapy

Tumor necrosis factor (TNF) is a biomarker of inflammation whose levels are elevated in patients with several diseases associated with dysregulation of the immune response. The main limitations of currently used anti-TNF therapies are the induction of immunodepression, which in many cases leads to serious adverse effects such as infection and cancer, and the inability to cross the blood-brain barrier in neuroinflammatory conditions. Melatonin, in addition to being a chronobiotic compound, is widely known for its antioxidant and immunomodulatory capacity to control inflammatory processes in different pathological contexts. The aim of the present review is to address human-based studies that describe the effect of melatonin on TNF production. The review includes all the articles published in PubMed databases until April 15, 2024. After depuration, 45 studies were finally included in the review, 23 related to the in vitro action of melatonin in human cells and 22 in vivo studies in humans. Most of the data reviewed support the idea that melatonin has an immunosuppressive effect on TNF levels, which, together with its low toxicity profile, low cost, and ability to cross the blood-brain barrier, points to melatonin as a potential anti-TNF therapy. Therefore, improving our knowledge of the action of melatonin in regulating TNF through appropriate clinical trials would reveal the true potential of this molecule as a possible anti-TNF therapy.

Irregular sleep-wake rhythm disorder: From the pathophysiologic perspective to the treatment

Irregular sleep-wake rhythm disorder (ISWRD) is an intrinsic circadian rhythm disorder caused by loss of the brain's circadian regulation, through changes of the input and/or output to the suprachiasmatic nucleus (SCN), or of the SCN itself. Although there are limited prevalence data for this rare disease, ISWRD is associated with neurodegenerative disorders, including the Alzheimer disease (AD) and the Parkinson disease (PD), which will become increasingly prevalent in an aging population. It additionally presents in childhood developmental disorders, psychiatric disorders, and traumatic brain injury (TBI). Patients present with unpredictable, short sleep periods over a 24-h period, with significant day-to-day and weekly variability. Symptoms manifest as insomnia and excessive daytime sleepiness. Sleep logs and actigraphy monitoring capture rest-activity patterns required for diagnosis. Treatment aims to enhance external circadian cues through timed light therapy, behavioral activity regimens, and melatonin, but efficacy remains quite limited. Pathophysiology of ISWRD in association with various diseases and their specific management are discussed. There is a need for further investigation of disease pathophysiology, development of widely applicable tools for diagnosis, and development of treatments.

Sleep-Related Disorders in Parkinson's Disease: Mechanisms, Diagnosis, and Therapeutic Approaches

BACKGROUND

Parkinson's Disease (PD) is frequently associated with a spectrum of sleep-related disorders, including insomnia, Excessive Daytime Sleepiness (EDS), REM sleep Behaviour Disorder (RBD), Restless Legs Syndrome (RLS), and Sleep-related Breathing Disorders (SBDs). These disorders significantly impact PD patients' Quality of Life (QoL) and present unique diagnostic and therapeutic challenges.

METHODS

This review has explored the intricate relationship between PD and sleep-related disorders, emphasizing their distinctive features and underlying neurobiological mechanisms. It aimed to consolidate current knowledge to optimize clinical management and improve patient care. The profound impact of these disorders on QoL has been evaluated, along with precise diagnostic methodologies. Additionally, various therapeutic strategies, including pharmacological treatments, nonpharmacological interventions, and device-aided therapies, have been examined.

RESULTS

Sleep-related disorders are prevalent among PD patients. Specifically, RBD exhibits a prevalence of 40-50%, often preceding the onset of motor symptoms, indicating its potential as an early marker of PD. Despite their significant impact on QoL, these non-motor symptoms are frequently under-recognized and inadequately managed in clinical practice. Pharmacological treatments, along with nonpharmacological interventions, like cognitive-behavioral therapy for insomnia and lifestyle modifications, have shown varied efficacy. Device-aided therapies have also demonstrated the potential to improve sleep-related disorders and overall non-motor symptom burden.

CONCLUSION

Effective management of sleep-related disorders in PD calls for personalized, comprehensive, and multimodal therapeutic approaches. This requires the collaborative efforts of neurologists, sleep specialists, psychiatrists, and other healthcare professionals. Future research should focus on the intricate relationship between PD and sleep disorders, aiming to develop innovative treatments and significantly improve patient outcomes.

Melatonin on sleep in Parkinson's disease: A randomized double blind placebo controlled trial

BACKGROUND

Sleep disturbances are one of the most common non-motor symptoms in Idiopathic Parkinson's Disease (IPD) patients. However, the effect of melatonin on sleep problems in Parkinson's disease patients is unclear.

AIMS AND OBJECTIVES

To study the effect of melatonin on sleep in IPD patients through subjective and objective assessment.

METHODS

Between August 2023 to February 2024, we conducted a randomized, double-blind, placebo-controlled trial on IPD patients. We randomized eligible subjects to melatonin (3 mg) (n = 43) or placebo (n = 43) for 8 weeks. The primary endpoint was sleep quality assessed through the Pittsburgh sleep quality index and daytime sleepiness using Epworth sleepiness scale. Secondary endpoints were polysomnographic sleep parameters, quality of life, motor and non-motor symptoms. Assessments were done at baseline and at the end of 8 weeks.

RESULTS

We screened 107 IPD patients and 86 patients were included in the study. Seventy three patients (melatonin, 35 and placebo, 38) completed the study. The mean change in Pittsburgh Sleep Quality Index (PSQI) score between the two groups was 1.87 (95 % CI: 1.5-2.1; p = 0.001) and Epworth Sleepiness Scale (ESS) score was 1.25 (95 % CI: 0.80-1.71; p = 0.001) favoring melatonin. The mean difference between the two groups for Non-Motor Symptoms Scale (NMSS) was 6.11 (95 % CI 5.27-6.92; p = 0.001), Parkinson's Disease Questionnaire (PDQ 39) 8.12 (95 % CI 6.97-9.50; p = 0.001) & Polysomnography (PSG) parameters [sleep latency 8.36 (95 % CI 4.38-12.34; p = 0.001) and total sleep time 14.51 (95 % CI 5.00-24.41; p = 0.005)] favoring melatonin. Side effects attributable to melatonin were minimal.

CONCLUSION

Melatonin is an effective and safe treatment option for sleep problems in PD patients, and beneficial effects on sleep quality are associated with improved non-motor symptoms and quality of life. We need to emphasize the fact that though we had statistically significant changes in our outcomes, it is not clear whether such changes would have real-life impact (meaningfulness) that would be relevant to licensing authorities or management as patients in our study are young, have short disease duration, have high use of anticholinergics and on modest levodopa equivalent dose. So, we are doubtful if this could be generalized to the typical PD population who are older, have longer disease duration and are on potentially sedating medications or not.

Pharmacological and non-pharmacological management of sleep disturbances in Parkinson's disease: if when and how

INTRODUCTION

Sleep dysfunction occurs in various forms and is a bothersome and intrusive non-motor symptom of Parkinson's disease (PD). Frequently undiagnosed, their poor management can have a great impact on the quality of life of PD patients and their caregivers.

AREAS COVERED

This article covers the safety and efficacy of pharmacological strategies for the management of the most frequent sleep disturbances in Parkinson's disease. Non-pharmacological aspects are also discussed, but these are not the main focus. Literature searches using electronic databases (Medline, Cochrane Library) and systematic checking of references from review articles/other reports were performed.

EXPERT OPINION

Melatonin and clonazepam are the most commonly used therapies for the management of REM sleep behavior disorder (RBD). The most used pharmacological wake-promoting agents in the treatment of excessive daytime sleepiness (EDS) are modafinil and caffeine. Poor nocturnal sleep quality is usually linked to EDS, thus proper sleep hygiene is recommended. As nocturnal motor symptoms are commonly associated with sleep fragmentation and early morning off, optimization of dopaminergic treatment during nighttime is highly recommended for the proper management of insomnia. Further interventions include eszopiclone and melatonin for the management of insomnia. Therapeutic options for restless legs syndrome (RLS) include calcium channel alpha-2-delta ligands and low-dose dopamine agonists (DA). Further confirmatory evidence is needed before the general recommendation of these treatments.

Setting the clinical context to non-motor symptoms reflected by Park-pain, Park-sleep, and Park-autonomic subtypes of Parkinson's disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) are well described in both clinical practice and the literature, enabling their management and enhancing our understanding of PD. NMS can dominate the clinical pictures and NMS subtypes have recently been proposed, initially based on clinical observations, and later confirmed in data driven analyses of large datasets and in biomarker-based studies. In this chapter, we provide an update on what is known about three common subtypes of NMS in PD. The pain (Park-pain), sleep dysfunction (Park-sleep), and autonomic dysfunction (Park-autonomic), providing an overview of their individual classification, clinical manifestation, pathophysiology, diagnosis, and potential treatments.

Significant potential of melatonin therapy in Parkinson's disease - a meta-analysis of randomized controlled trials

Objective

Since its discovery as an antioxidant, melatonin has been increasingly recognized for its therapeutic potential beyond sleep disturbances in neurodegenerative disorders. This study aims to evaluate efficacy of various melatonin doses, treatment durations, and formulations, in alleviating motor symptoms and sleep disturbances in Parkinson's disease, the second most common neurodegenerative disorder worldwide.

Methods

PubMed, Cochrane Library, ClinicalTrials.gov and other databases were systematically searched to retrieve randomized controlled trials (RCTs) administrating melatonin to Parkinson's disease patients until June 10th, 2023. Outcomes including Unified Parkinson Disease Rating Scale (UPDRS) scores and Pittsburgh Sleep Quality Index (PSQI) scores, were pooled and reported as mean differences (MD) with 95% confidence intervals (CIs). Meta-analysis was performed using an inverse variance random-effects model in Review Manager 5.4 software. Trial Sequential Analysis was performed to avoid false-positive results from random errors.

Results

Five RCTs with a total of 155 patients were included. Statistically significant reductions in UPDRS total scores were observed in groups receiving Melatonin ≥10 mg/day (MD = -11.35, 95% CI: -22.35 to -0.35, I2 = 0%, p = 0.04) and immediate release formulations (MD = -11.35, 95% CI: -22.35 to -0.35, I2 = 0%, p = 0.04). No significant effects on individual UPDRS II, III, and IV scores were observed, regardless of melatonin dosage and treatment duration. Moreover, significant improvements in PSQI scores were observed with only immediate-release melatonin formulations (MD = -2.86, 95% CI: -4.74 to -0.97, I2 = 0%, p = 0.003).

Conclusion

Melatonin ≥10 mg/day for a minimum duration of ≥12 weeks in immediate-release formulations consistently demonstrated significant therapeutic potential in improving motor symptom and sleep disturbances in Parkinson disease. However, further trials are warranted to investigate its impact when initiated early in the disease course to fully explore its true therapeutic potential.

Systematic review registration

Unique identifier: CRD42023427491 (PROSPERO).

An overview of the effects of levodopa and dopaminergic agonists on sleep disorders in Parkinson's disease

Sleep disorders are among the most common nonmotor symptoms in Parkinson's disease and are associated with reduced cognition and health-related quality of life. Disturbed sleep can often present in the prodromal or early stages of this neurodegenerative disease, rendering it crucial to manage and treat these symptoms. Levodopa and dopaminergic agonists are frequently prescribed to treat motor symptoms in Parkinson's disease, and there is increasing interest in how these pharmacological agents affect sleep and their effect on concomitant sleep disturbances and disorders. In this review, we discuss the role of dopamine in regulating the sleep-wake state and the impact of neurodegeneration on sleep. We provide an overview of the effects of levodopa and dopaminergic agonists on sleep architecture, insomnia, excessive daytime sleepiness, sleep-disordered breathing, rapid eye movement sleep behavior disorder, and restless legs syndrome in Parkinson's disease. Levodopa and dopaminergic drugs may have different effects, beneficial or adverse, depending on dosing, method of administration, and differential effects on the different dopamine receptors. Future research in this area should focus on elucidating the specific mechanisms by which these drugs affect sleep in order to better understand the pathophysiology of sleep disorders in Parkinson's disease and aid in developing suitable therapies and treatment regimens.

CITATION

Scanga A, Lafontaine A-L, Kaminska M. An overview of the effects of levodopa and dopaminergic agonists on sleep disorders in Parkinson's disease. J Clin Sleep Med. 2023;19(6):1133-1144.

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.

The Relationships Among Metal Homeostasis, Mitochondria, and Locus Coeruleus in Psychiatric and Neurodegenerative Disorders: Potential Pathogenetic Mechanism and Therapeutic Implications

While alterations in the locus coeruleus-noradrenergic system are present during early stages of neuropsychiatric disorders, it is unclear what causes these changes and how they contribute to other pathologies in these conditions. Data suggest that the onset of major depressive disorder and schizophrenia is associated with metal dyshomeostasis that causes glial cell mitochondrial dysfunction and hyperactivation in the locus coeruleus. The effect of the overactive locus coeruleus on the hippocampus, amygdala, thalamus, and prefrontal cortex can be responsible for some of the psychiatric symptoms. Although locus coeruleus overactivation may diminish over time, neuroinflammation-induced alterations are presumably ongoing due to continued metal dyshomeostasis and mitochondrial dysfunction. In early Alzheimer's and Parkinson's diseases, metal dyshomeostasis and mitochondrial dysfunction likely induce locus coeruleus hyperactivation, pathological tau or α-synuclein formation, and neurodegeneration, while reduction of glymphatic and cerebrospinal fluid flow might be responsible for β-amyloid aggregation in the olfactory regions before the onset of dementia. It is possible that the overactive noradrenergic system stimulates the apoptosis signaling pathway and pathogenic protein formation, leading to further pathological changes which can occur in the presence or absence of locus coeruleus hypoactivation. Data are presented in this review indicating that although locus coeruleus hyperactivation is involved in pathological changes at prodromal and early stages of these neuropsychiatric disorders, metal dyshomeostasis and mitochondrial dysfunction are critical factors in maintaining ongoing neuropathology throughout the course of these conditions. The proposed mechanistic model includes multiple pharmacological sites that may be targeted for the treatment of neuropsychiatric disorders commonly.

Polysomnographic and Clinical Parameters before and after Zonisamide Therapy for Parkinson's Disease

Objective Sleep disturbance is a common nonmotor symptom associated with a decreased quality of life in patients with Parkinson's disease (PD). In this study, we evaluated the effects of zonisamide on motor and non-motor symptomology in patients with PD, especially with respect to objective sleep assessments conducted via polysomnography. Methods We conducted a 12-week, open-label study to assess the effects of zonisamide. The patients received 25 mg/day of zonisamide and underwent overnight polysomnography prior to and after 12 weeks of zonisamide treatment. They were assessed for their cognitive function (Mini-Mental State Examination and the Japanese version of the Montreal Cognitive Assessment), gait function (Timed Up-and-Go Test, 10-m Gait Walk Test), Parkinson's symptomology (Movement Disorder Society Revision of the Unified Parkinson's Disease Rating Scale parts 2 and 3), and self-reported sleep (Epworth Sleepiness Score, Parkinson's Disease Sleep Scale-2). Results Six patients completed the study. Polysomnographic data revealed a statistically significant increase in the percentage of time spent in sleep stage N2 (10.8%±9.2%, p=0.031) and a declining trend in the percentage of time spent in sleep stage N1 (-8.9%±12.7%, p=0.063). Although none of the patients had sleep stage N3 at baseline, 3 of the 6 patients experienced sleep stage N3 (1.1-5.4%) after 12 weeks of zonisamide treatment. The other polysomnographic parameters and clinical scores showed no statistically significant differences. Conclusions This preliminary study demonstrated that zonisamide improved objective sleep parameters measured by polysomnography in patients with PD.

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.

Oxidative Stress and Aging as Risk Factors for Alzheimer's Disease and Parkinson's Disease: The Role of the Antioxidant Melatonin

Aging and neurodegenerative diseases share common hallmarks, including mitochondrial dysfunction and protein aggregation. Moreover, one of the major issues of the demographic crisis today is related to the progressive rise in costs for care and maintenance of the standard living condition of aged patients with neurodegenerative diseases. There is a divergence in the etiology of neurodegenerative diseases. Still, a disturbed endogenous pro-oxidants/antioxidants balance is considered the crucial detrimental factor that makes the brain vulnerable to aging and progressive neurodegeneration. The present review focuses on the complex relationships between oxidative stress, autophagy, and the two of the most frequent neurodegenerative diseases associated with aging, Alzheimer's disease (AD) and Parkinson's disease (PD). Most of the available data support the hypothesis that a disturbed antioxidant defense system is a prerequisite for developing pathogenesis and clinical symptoms of ADs and PD. Furthermore, the release of the endogenous hormone melatonin from the pineal gland progressively diminishes with aging, and people's susceptibility to these diseases increases with age. Elucidation of the underlying mechanisms involved in deleterious conditions predisposing to neurodegeneration in aging, including the diminished role of melatonin, is important for elaborating precise treatment strategies for the pathogenesis of AD and PD.

The multimodal effect of circadian interventions in Parkinson's disease: A narrative review

BACKGROUND

The circadian system and its dysfunction in persons with Parkinson's disease (PwP) has a clear impact on both motor and non-motor symptoms. Examples include circadian patterns in motor disability, with worsening of symptoms throughout the day, but also the existence of similar patterns in non-motor symptoms.

OBJECTIVE

In this narrative review, we discuss the role of the circadian system, we address the role of dopamine in this system, and we summarise the evidence that supports the use of circadian system treatments for motor and non-motor symptoms in PwP.

METHODS

A systematic search in PubMed and Web of Science database was performed and the final search was performed in November 2021. We included articles whose primary aim was to investigate the effect of melatonin, melatonin agonists, and light therapy in PwP.

RESULTS

In total 25 articles were retrieved. Of these, 12 were related to bright light therapy and 13 to melatonin or/and melatonin agonists. Most, but not all, studies showed that melatonin and melatonin agonists and light therapy induced improvements in measures of sleep, depression, motor function, and some also cognitive function and other non-motor symptoms. For some of these outcomes, including daytime sleepiness, depressive symptoms, and some motor symptoms, there is level 2 B evidence for the use of circadian treatments in PwP.

CONCLUSIONS

Treatment with bright light therapy, exogenous melatonin and melatonin agonists seems to have not only positive effects on sleep quality and depression but also on motor function in PwP. Drawbacks in earlier work include the relatively small number of participants and the heterogeneity of outcome measures. Further large and well-designed trials are needed to address these shortcomings and to confirm or refute the possible merits of the circadian system as a treatment target in PwP.

Sleep Dysfunction in Huntington's Disease: Impacts of Current Medications and Prospects for Treatment

Sleep dysfunction is highly prevalent in Huntington's disease (HD). Increasing evidence suggests that such dysfunction not only impairs quality of life and exacerbates symptoms but may even accelerate the underlying disease process. Despite this, current HD treatment approaches neither consider the impact of commonly used medications on sleep, nor directly tackle sleep dysfunction. In this review, we discuss approaches to these two areas, evaluating not only literature from clinical studies in HD, but also that from parallel neurodegenerative conditions and preclinical models of HD. We conclude by summarizing a hierarchical framework of current medications with regard to their impact on sleep, and by outlining key emerging sleep therapies.

Should patients with Parkinson’s disease only visit a neurologist’s office? - a narrative review of neuropsychiatric disorders among people with Parkinson’s disease

Introduction: Parkinson’s disease is a neurodegenerative disease that is often accompanied by disorders such as depression, psychotic disorders, cognitive disorders, anxiety disorders, sleep disorders, impulse control disorders. The aim of the study was to review the literature and present the characteristics of neuropsychiatric disorders occurring in people suffering from Parkinson’s disease, with the specification of the above-mentioned disorders.

Material and method: The literature available on the PubMed platform from 1986 to 2022 was reviewed using the following keywords: Parkinson’s disease, depression, anxiety disorders, psychotic disorders, sleep disorders, cognitive disorders, impulse control disorders. Original studies, reviews, meta-analyzes and internet sources were analyzed.

Results: The above-mentioned neuropsychiatric disorders appear with different frequency among people suffering from Parkinson’s disease and occur at different times of its duration or even precede its onset for many years. The non-motor symptoms in the form of depressed mood, energy loss or changes in the rhythm of the day may result in a delay of appropriate therapy and thus in complications. Neuropathological changes in the course of Parkinson’s disease as well as dopaminergic drugs used in its therapy influence the development of neuropsychiatric disorders.

Conclusions: In order to avoid misdiagnosis, practitioners should use, e.g. scales intended for patients with Parkinson’s disease. To prevent the consequences of the aforementioned disease entities, methods of early diagnosis, determination of risk factors and standardization of the treatment process must be determined. Consistent care for patients with Parkinson’s disease is significant, not only in the neurological field, but also in the psychiatric one.

Mammalian circadian networks mediated by the suprachiasmatic nucleus

The brain has a complex structure composed of hundreds of regions, forming networks to cooperate body functions. Therefore, understanding how various brain regions communicate with each other and with peripheral organs is important to understand human physiology. The suprachiasmatic nucleus (SCN) in the brain is the circadian pacemaker. The SCN receives photic information from the environment and conveys this to other parts of the brain and body to synchronize all circadian clocks. The circadian clock is an endogenous oscillator that generates daily rhythms in metabolism and physiology in almost all cells via a conserved transcriptional-translational negative feedback loop. So, the information flow from the environment to the SCN to other tissues synchronizes locally distributed circadian clocks to maintain homeostasis. Thus, understanding the circadian networks and how they adjust to environmental changes will better understand human physiology. This review will focus on circadian networks mediated by the SCN to understand how the environment, brain, and peripheral tissues form networks for cooperation.

Melatonin in sleep disorders

Melatonin is the main hormone involved in the control of the sleep-wake cycle. It is easily synthesisable and can be administered orally, which has led to interest in its use as a treatment for insomnia. Moreover, as production of the hormone decreases with age, in inverse correlation with the frequency of poor sleep quality, it has been suggested that melatonin deficit is at least partly responsible for sleep disorders. Treating this age-related deficit would therefore appear to be a natural way of restoring sleep quality, which is lost as patients age. However, despite the undeniable theoretical appeal of this approach to insomnia, little scientific evidence is available that supports any benefit of this substitutive therapy. Furthermore, the most suitable dose ranges and pharmaceutical preparations for melatonin administration are yet to be clearly defined. This review addresses the physiology of melatonin, the different pharmaceutical preparations, and data on its clinical usefulness.

Effects of melatonin prolonged-release on both sleep and motor symptoms in Parkinson’s disease: a preliminary evidence

Background

Sleep-related symptoms, especially insomnia, are frequently reported by patients with Parkinson’s disease (PD) and can markedly affect motor symptoms and impair patients’ quality of life. Melatonin has been shown to improve sleep in PD patients. This pilot study aimed at evaluating the effects of a 3-month treatment with 2 mg melatonin prolonged-release (PR) on sleep and motor disability in PD patients.

Materials and methods

Twelve PD patients under stable antiparkinsonian treatment were enrolled in the study. Before treatment (T0), motor dysfunction was assessed with Unified Parkinson’s Disease Rating Scale (UPDRS-III) and sleep architecture with polysomnography. Subjective sleep quality was also assessed through Pittsburgh Sleep Quality Index (PSQI) and daytime somnolence with Epworth Sleepiness Scale (ESS). Patients then started melatonin PR and all measures were repeated at the end of treatment after 3 months (T1).

Results

Sleep latency significantly decreased from T0 to T1, but no other significant differences were found in PSG parameters. Melatonin PR treatment significantly reduced the ESS scores from T0 to T1, while the PSQI scores presented a trend of improvement from T0 to T1. Motor dysfunction was not improved by melatonin PR, although there was a trend in decreasing UPDRS-III. Both clinical global improvement and patient clinical global impression documented an improvement in insomnia symptoms at T1.

Conclusions

These findings suggest that melatonin may improve sleep symptoms in PD patients, although further evidence is needed in larger controlled studies to confirm these results and explore the possible direct and indirect influence of sleep improvement on motor dysfunction.

Safety of higher doses of melatonin in adults: A systematic review and meta-analysis

Melatonin is commonly used for sleep and jetlag at low doses. However, there is less documentation on the safety of higher doses, which are being increasingly used for a wide variety of conditions, including more recently COVID-19 prevention and treatment. The aim of this review was to investigate the safety of higher doses of melatonin in adults. Medline, Scopus, Embase and PsycINFO databases from inception until December 2019 with convenience searches until October 2020. Randomised controlled trials investigating high-dose melatonin (≥10 mg) in human adults over 30 years of age were included. Two investigators independently abstracted articles using PRISMA guidelines. Risk of bias was assessed by a committee of three investigators. 79 studies were identified with a total of 3861 participants. Studies included a large range of medical conditions. The meta-analysis was pooled data using a random effects model. The outcomes examined were the number of adverse events (AEs), serious adverse events (SAEs) and withdrawals due to AEs. A total of 29 studies (37%) made no mention of the presence or absence of AEs. Overall, only four studies met the pre-specified low risk of bias criteria for meta-analysis. In that small subset, melatonin did not cause a detectable increase in SAEs (Rate Ratio = 0.88 [0.52, 1.50], p = .64) or withdrawals due to AEs (0.93 [0.24, 3.56], p = .92), but did appear to increase the risk of AEs such as drowsiness, headache and dizziness (1.40 [1.15, 1.69], p < .001). Overall, there has been limited AE reporting from high-dose melatonin studies. Based on this limited evidence, melatonin appears to have a good safety profile. Better safety reporting in future long-term trials is needed to confirm this as our confidence limits were very wide due to the paucity of suitable data.

Melatonin as the Cornerstone of Neuroimmunoendocrinology

Much attention has been recently drawn to studying melatonin – a hormone whose synthesis was first found in the epiphysis (pineal gland). This interest can be due to discovering the role of melatonin in numerous physiological processes. It was the discovery of melatonin synthesis in endocrine organs (pineal gland), neural structures (Purkinje cells in the cerebellum, retinal photoreceptors), and immunocompetent cells (T lymphocytes, NK cells, mast cells) that triggered the evolution of new approaches to the unifield signal regulation of homeostasis, which, at the turn of the 21st century, lead to the creation of a new integral biomedical discipline — neuroimmunoendocrinology. While numerous hormones have been verified over the last decade outside the “classical” locations of their formation, melatonin occupies an exclusive position with regard to the diversity of locations where it is synthesized and secreted. This review provides an overview and discussion of the major data regarding the role of melatonin in various physiological and pathological processes, which affords grounds for considering melatonin as the “cornerstone” on which neuroimmunoendocrinology has been built as an integral concept of homeostasis regulation.

Melatonin Treatment for Sleep Disorders in Parkinson's Disease: A Meta-Analysis and Systematic Review

Objective

The efficacy of melatonin on sleep disorders in Parkinson's disease (PD) is still unclear. The purpose of this study was to investigate the efficacy of melatonin on sleep disorders in PD by summarizing evidence from randomized clinical trials (RCTs).

Methods

PubMed, Cochrane Library, EMBASE, and Web of Science databases were searched for studies published before 20 August 2021. Results were analyzed using Review Manager 5.2 software. We used Trial Sequential Analysis (TSA) software to avoid false-positive results caused by random errors.

Results

We included 7 studies in this systematic review and meta-analysis. The results of the meta-analysis showed that compared with placebo, the subjective sleep quality of patients with PD significantly improved after melatonin treatment (MD = −2.19, 95% CI: −3.53 to −0.86, P = 0.001). In the systematic review, we qualitatively analyzed the efficacy of melatonin on the objective sleep quality of patients with PD, and the results showed that melatonin exerted a positive effect with good safety and tolerability. However, there was no significant improvement in excessive daytime sleepiness assessed by the Epworth Sleepiness Scale (ESS).

Conclusion

We found that melatonin can significantly improve the subjective and objective sleep quality of patients with PD with good safety and tolerability. Melatonin could be considered an effective treatment for insomnia in patients with PD.

Roles of clock genes in the pathogenesis of Parkinson's disease

Parkinson's disease (PD) is a common motor disorder that has become increasingly prevalent in the ageing population. Recent works have suggested that circadian rhythms disruption is a common event in PD patients. Clock genes regulate the circadian rhythm of biological processes in eukaryotic organisms, but their roles in PD remain unclear. Despite this, several lines of evidence point to the possibility that clock genes may have a significant impact on the development and progression of the disease. This review aims to consolidate recent understanding of the roles of clock genes in PD. We first summarized the findings of clock gene expression and epigenetic analyses in PD patients and animal models. We also discussed the potential contributory role of clock gene variants in the development of PD and/or its symptoms. We further reviewed the mechanisms by which clock genes affect mitochondrial dynamics as well as the rhythmic synthesis and secretion of endocrine hormones, the impairment of which may contribute to the development of PD. Finally, we discussed the limitations of the currently available studies, and suggested future potential studies to deepen our understanding of the roles of clock genes in PD pathogenesis.

Novel Series of Dual NRF2 Inducers and Selective MAO-B Inhibitors for the Treatment of Parkinson’s Disease

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease. It is characterized by a complex network of physiopathological events where oxidative stress plays a central role among other factors such as neuroinflammation and protein homeostasis. Nuclear factor-erythroid 2 p45-related factor 2 (NRF2) has a multitarget profile itself as it controls a plethora of cellular processes involved in the progression of the disease. In this line, we designed a novel family of 2-(1H-indol-3-yl)ethan-1-amine derivatives as NRF2 inducers with complementary activities. Novel compounds are based on melatonin scaffold and include, among other properties, selective monoamine oxidase B (MAO-B) inhibition activity. Novel multitarget compounds exhibited NRF2 induction activity and MAO-B selective inhibition, combined with anti-inflammatory, antioxidant, and blood–brain barrier permeation properties. Furthermore, they exert neuroprotective properties against oxidative stress toxicity in PD-related in vitro. Hit compound 14 reduced oxidative stress markers and exerted neuroprotection in rat striatal slices exposed to 6-hydroxydopamine or rotenone. In conclusion, we developed a promising family of dual NRF2 inducers and selective MAO-B inhibitors that could serve as a novel therapeutic strategy for PD treatment.

New approaches to treatments for sleep, pain and autonomic failure in Parkinson's disease - Pharmacological therapies

Non-motor symptoms (NMSs) are highly prevalent throughout the course of Parkinson's disease (PD). Pain, autonomic dysfunction and sleep disturbances remain at the forefront of the most common NMSs; their treatment is challenging and their effect on the quality of life of both patients and caregivers detrimental. Yet, the landscape of clinical trials in PD is still dominated by therapeutic strategies seeking to ameliorate motor symptoms; subsequently, effective strategies to successfully treat NMSs remain a huge unmet need. Wider awareness among industry and researchers is thus essential to give rise to development and delivery of high-quality, large-scale clinical trials in enriched populations of patients with PD-related pain, autonomic dysfunction and sleep. In this review, we discuss recent developments in the field of pharmacological treatment strategies designed or re-purposed to target three key NMSs: pain, autonomic dysfunction and sleep disturbances. We focus on emerging evidence from recent clinical trials and outline some exciting and intriguing findings that call for further investigations.

Zonisamide for the Efficacy of Sleep Abnormality in Parkinson's Disease (ZEAL Study): A Protocol for Randomized Controlled Trials

Background: Sleep disorders are one of the most frequent non-motor symptoms of Parkinson's disease (PD), and the efficacy of dopaminergic agents remains controversial. Clinical randomized control trials for the treatment of sleep disorders in PD are limited. Zonisamide (1,2-benzisoxazole-3-methanesulfonamide) improved motor symptoms and wearing-off in patients with PD. Patients with PD were reported to have dream-enacting behavior that was resolved after treatment with zonisamide. This study aimed to verify the safety and efficacy of zonisamide for sleep disorders and rapid eye movement (REM) sleep behavioral disorders using a mobile two-channel electroencephalography (EEG)/electrooculography (EOG) recording system.

Methods and Analysis: The present study is a randomized placebo-controlled trial to determine the efficacy of zonisamide for sleep disorders in patients with PD. This study was designed to be single-blind, but the subject allocation is randomized by an independent allocation manager via computer-generated block randomization. The subjects in the treatment group took zonisamide (25 mg per day) before bedtime for 28 days. The sleep index is analyzed using a portable EEG/EOG recording system collected on two consecutive nights within 7 days prior to the intervention and reobtained on one night within 2 days after the 28-day administration of zonisamide. The amount of change in sleep efficiency before and after the 28-day administration will be compared between the zonisamide treatment group and placebo group concerning the primary endpoint. As for the secondary endpoint, the change in the ratio of other sleep parameters, including REM sleep without atonia, or sleep architecture will be evaluated.

Ethics and Dissemination: The protocol was approved by the Nara Medical University Certified Review Board (CRB5200002). The trial was notified and registered with the Japan Registry of Clinical Trials (jRCTs051200160). Written informed consent will be obtained from every participant using informed consent approved by the CRB. The results of this trial will be disseminated through peer-reviewed scientific journals.

Management of Sleep Disturbances in Parkinson's Disease

Parkinson's disease (PD) is defined by its motor symptoms rigidity, tremor, and akinesia. However, non-motor symptoms, particularly autonomic disorders and sleep disturbances, occur frequently in PD causing equivalent or even greater discomfort than motor symptoms effectively decreasing quality of life in patients and caregivers. Most common sleep disturbances in PD are insomnia, sleep disordered breathing, excessive daytime sleepiness, REM sleep behavior disorder, and sleep-related movement disorders such as restless legs syndrome. Despite their high prevalence, therapeutic options in the in- and outpatient setting are limited, partly due to lack of scientific evidence. The importance of sleep disturbances in neurodegenerative diseases has been further emphasized by recent evidence indicating a bidirectional relationship between neurodegeneration and sleep. A more profound insight into the underlying pathophysiological mechanisms intertwining sleep and neurodegeneration might lead to unique and individually tailored disease modifying or even neuroprotective therapeutic options in the long run. Therefore, current evidence concerning the management of sleep disturbances in PD will be discussed with the aim of providing a substantiated scaffolding for clinical decisions in long-term PD therapy.

Circadian rhythms in neurodegenerative disorders

Endogenous biological clocks, orchestrated by the suprachiasmatic nucleus, time the circadian rhythms that synchronize physiological and behavioural functions in humans. The circadian system influences most physiological processes, including sleep, alertness and cognitive performance. Disruption of circadian homeostasis has deleterious effects on human health. Neurodegenerative disorders involve a wide range of symptoms, many of which exhibit diurnal variations in frequency and intensity. These disorders also disrupt circadian homeostasis, which in turn has negative effects on symptoms and quality of life. Emerging evidence points to a bidirectional relationship between circadian homeostasis and neurodegeneration, suggesting that circadian function might have an important role in the progression of neurodegenerative disorders. Therefore, the circadian system has become an attractive target for research and clinical care innovations. Studying circadian disruption in neurodegenerative disorders could expand our understanding of the pathophysiology of neurodegeneration and facilitate the development of novel, circadian-based interventions for these disabling disorders. In this Review, we discuss the alterations to the circadian system that occur in movement (Parkinson disease and Huntington disease) and cognitive (Alzheimer disease and frontotemporal dementia) neurodegenerative disorders and provide directions for future investigations in this field.

Association between Sleep, Alzheimer's, and Parkinson's Disease

The majority of neurodegenerative diseases are pathologically associated with protein misfolding and aggregation. Alzheimer's disease (AD) is a type of dementia that slowly affects memory and cognitive function, and is characterized by the aggregation of the β-amyloid protein and tau neurofibrillary tangles in the brain. Parkinson's disease (PD) is a movement disorder typically resulting in rigidity and tremor, which is pathologically linked to the aggregation of α-synuclein, particularly in dopaminergic neurons in the midbrain. Sleep disorders commonly occur in AD and PD patients, and it can precede the onset of these diseases. For example, cognitively normal older individuals who have highly fragmented sleep had a 1.5-fold increased risk of subsequently developing AD. This suggests that sleep abnormalities may be a potential biomarker of these diseases. In this review, we describe the alterations of sleep in AD and PD, and discuss their potential in the early diagnosis of these diseases. We further discuss whether sleep disturbance could be a target for the treatment of these diseases.

Pharmacological Interventions for REM Sleep Behavior Disorder in Parkinson's Disease: A Systematic Review

To review the therapeutic effects of drugs on REM sleep behavior disorder (RBD) in Parkinson's disease (PD) by searching the MEDLINE/PubMed, Embase, Cochrane, and CBM databases. According to the inclusion and exclusion criteria, studies were included after excluding duplicate data. We evaluated the safety and efficacy of pharmacological intervention to improve RBD in patients with Parkinson's disease (PD-RBD). This systematic review mainly describes the drugs that can be used to treat PD-RBD patients. The results have shown that melatonin can be used as the first-line drug for PD-RBD, and clonazepam provides significant improvement on PD-RBD, androtigotine can be used as an alternative drug. However, further large-scale clinical trial studies are still needed to provide the best guidelines for the pharmacological treatment of PD-RBD.

Melatonin as a Reducer of Neuro- and Vasculotoxic Oxidative Stress Induced by Homocysteine

The antioxidant properties of melatonin can be successfully used to reduce the effects of oxidative stress caused by homocysteine. The beneficial actions of melatonin are mainly due to its ability to inhibit the generation of the hydroxyl radical during the oxidation of homocysteine. Melatonin protects endothelial cells, neurons, and glia against the action of oxygen radicals generated by homocysteine and prevents the structural changes in cells that lead to impaired contractility of blood vessels and neuronal degeneration. It can be, therefore, assumed that the results obtained in experiments performed mainly in the in vitro models and occasionally in animal models may clear the way to clinical applications of melatonin in patients with hyperhomocysteinemia, who exhibit a higher risk of developing neurodegenerative diseases (e.g., Parkinson’s disease or Alzheimer’s disease) and cardiovascular diseases of atherothrombotic etiology. However, the results that have been obtained so far are scarce and have seldom been performed on advanced in vivo models. All findings predominately originate from the use of in vitro models and the scarcity of clinical evidence is huge. Thus, this mini-review should be considered as a summary of the outcomes of the initial research in the field concerning the use of melatonin as a possibly efficient attenuator of oxidative stress induced by homocysteine.

Sleep Disturbance, Sleep Disorders and Co-Morbidities in the Care of the Older Person

Sleep complaints can be both common and complex in the older patient. Their consideration is an important aspect of holistic care, and may have an impact on quality of life, mortality, falls and disease risk. Sleep assessment should form part of the comprehensive geriatric assessment. If sleep disturbance is brought to light, consideration of sleep disorders, co-morbidity and medication management should form part of a multifaceted approach. Appreciation of the bi-directional relationship and complex interplay between co-morbidity and sleep in older patients is an important element of patient care. This article provides a brief overview of sleep disturbance and sleep disorders in older patients, in addition to their association with specific co-morbidities including depression, heart failure, respiratory disorders, gastro-oesophageal reflux disease, nocturia, pain, Parkinson's disease, dementia, polypharmacy and falls. A potential systematic multidomain approach to assessment and management is outlined, with an emphasis on non-pharmacological treatment where possible.

Melatonin as a Chronobiotic and Cytoprotective Agent in Parkinson's Disease

This article discusses the role that melatonin may have in the prevention and treatment of Parkinson’s disease (PD). In parkinsonian patients circulating melatonin levels are consistently disrupted and the potential therapeutic value of melatonin on sleep disorders in PD was examined in a limited number of clinical studies using 2–5 mg/day melatonin at bedtime. The low levels of melatonin MT1 and MT2 receptor density in substantia nigra and amygdala found in PD patients supported the hypothesis that the altered sleep/wake cycle seen in PD could be due to a disrupted melatonergic system. Motor symptomatology is seen in PD patients when about 75% of the dopaminergic cells in the substantia nigra pars compacta region degenerate. Nevertheless, symptoms like rapid eye movement (REM) sleep behavior disorder (RBD), hyposmia or depression may precede the onset of motor symptoms in PD for years and are index of worse prognosis. Indeed, RBD patients may evolve to an α-synucleinopathy within 10 years of RBD onset. Daily bedtime administration of 3–12 mg of melatonin has been demonstrated effective in RDB treatment and may halt neurodegeneration to PD. In studies on animal models of PD melatonin was effective to curtail symptomatology in doses that allometrically projected to humans were in the 40–100 mg/day range, rarely employed clinically. Therefore, double-blind, placebo-controlled clinical studies are urgently needed in this respect.

Systematic investigation of mouse models of Parkinson's disease by transcriptome mapping on a brain-specific genome-scale metabolic network

Genome-scale metabolic networks enable systemic investigation of metabolic alterations caused by diseases by providing interpretation of omics data. Although Mus musculus (mouse) is one of the most commonly used model organisms for neurodegenerative diseases, a brain-specific metabolic network model of mice has not yet been reconstructed. Here we reconstructed the first brain-specific metabolic network model of mice, iBrain674-Mm, by a homology-based approach, which consisted of 992 reactions controlled by 674 genes and distributed over 48 pathways. We validated the newly reconstructed network model by showing that it predicts healthy resting-state metabolic phenotypes of mouse brain compatible with the literature. We later used iBrain674-Mm to interpret various experimental mouse models of Parkinson's Disease (PD) at the transcriptome level. To this end, we applied a constraint-based modelling based biomarker prediction method called TIMBR (Transcriptionally Inferred Metabolic Biomarker Response) to predict altered metabolite production from transcriptomic data. Systemic analysis of seven different PD mouse models by TIMBR showed that the neuronal levels of glutamate, lactate, creatine phosphate, neuronal acetylcholine, bilirubin and formate increased in most of the PD mouse models, whereas the levels of melatonin, epinephrine, astrocytic formate and astrocytic bilirubin decreased. Although most of the predictions were consistent with the literature, there were some inconsistencies among different PD mouse models, signifying that there is no perfect experimental model to reflect PD metabolism. The newly reconstructed brain-specific genome-scale metabolic network model of mice can make important contributions to the interpretation and development of experimental mouse models of PD and other neurodegenerative diseases.

Exploratory pilot study of exogenous sustained-release melatonin on nocturia in Parkinson's disease

INTRODUCTION

Nocturia is one of the commonest non-motor symptoms in Parkinson's disease (PD). Nocturia has evolved from being understood as a symptom of urological disorders or neurogenic bladder dysfunction to being considered as a form of circadian dysregulation. Exogenous melatonin is known to help circadian function and can be an effective strategy for nocturia in PD.

METHODS

In this open-label, single-site, exploratory, phase 2 pilot study, adults with PD and nocturia underwent assessments using standardized questionnaires, urodynamics studies and a bladder scan. This was followed by completion of a frequency volume chart (FVC) and 2-week sleep diary. Sustained-release melatonin 2 mg was then administered once-nightly for 6 weeks. A repeat assessment using questionnaires, the FVC and sleep diary was performed whilst on treatment with melatonin. Companion or bed partners filled in sleep questionnaires to assess their sleep during the intervention.

RESULTS

Twenty patients (12 males; mean age 68.2 [SD = 7.8] years; mean PD duration 8.0 [±5.5] years) with PD reporting nocturia were included. Administration of melatonin was associated with a significant reduction in the primary outcome bother related to nocturia measured using the International Consultation on Incontinence Questionnaire Nocturia (ICIQ-N) (p = 0.01), number of episodes of nocturia per night (p = 0.013) and average urine volume voided at night (p = 0.013). No serious adverse events were reported. No significant improvement was noted in bed partner sleep scores.

CONCLUSIONS

In this preliminary open-label study, administration of sustained-release melatonin 2 mg was found to be safe for clinical use and was associated with significant improvements in night-time frequency and nocturnal voided volumes in PD patients.

Divergent Importance of Chronobiological Considerations in High- and Low-dose Melatonin Therapies

Melatonin has been used preclinically and clinically for different purposes. Some applications are related to readjustment of circadian oscillators, others use doses that exceed the saturation of melatonin receptors MT1 and MT2 and are unsuitable for chronobiological purposes. Conditions are outlined for appropriately applying melatonin as a chronobiotic or for protective actions at elevated levels. Circadian readjustments require doses in the lower mg range, according to receptor affinities. However, this needs consideration of the phase response curve, which contains a silent zone, a delay part, a transition point and an advance part. Notably, the dim light melatonin onset (DLMO) is found in the silent zone. In this specific phase, melatonin can induce sleep onset, but does not shift the circadian master clock. Although sleep onset is also under circadian control, sleep and circadian susceptibility are dissociated at this point. Other limits of soporific effects concern dose, duration of action and poor individual responses. The use of high melatonin doses, up to several hundred mg, for purposes of antioxidative and anti-inflammatory protection, especially in sepsis and viral diseases, have to be seen in the context of melatonin's tissue levels, its formation in mitochondria, and detoxification of free radicals.

Non-motor complications in late stage Parkinson's disease: recognition, management and unmet needs

Introduction: The burden of non-motor symptoms (NMS) is a major determinant of health-related quality of life in Parkinson's disease (PD), particularly at its late stage.Areas covered: The late stage is usually defined as the period from unstable advanced to the palliative stage, characterized by a combination of emerging treatment-resistant axial motor symptoms (freezing of gait, postural instability, falls and dysphagia), as well as both non-dopaminergic and dopaminergic NMS: cognitive decline, neuropsychiatric symptoms, aspects of dysautonomia, pain and sleep disturbances (insomnia and excessive day-time sleepiness). Here, the authors summarize the current knowledge on NMS dominating the late stage of PD and propose a pragmatic and clinically focused approach for their recognition and treatment.Expert opinion: The NMS progression pattern is complex and remains under-researched. While dopamine-dependent NMS may improve with dopamine replacement therapy, non-dopamine dependent NMS worsen progressively and culminate at the late stages of PD. Furthermore, some PD specific features could interact negatively with other comorbidities, multiple medication use and frailty - the evaluation of these aspects is important in the creation of personalized management plans in the late stage of PD.

Can chronopharmacology improve the therapeutic management of neurological diseases?

The importance of circadian rhythm dysfunctions in the pathophysiology of neurological diseases has been highlighted recently. Chronopharmacology principles imply that tailoring the timing of treatments to the circadian rhythm of individual patients could optimize therapeutic management. According to these principles, chronopharmacology takes into account the individual differences in patients' clocks, the rhythmic changes in the organism sensitivity to therapeutic and side effects of drugs, and the predictable time variations of disease. This review examines the current literature on chronopharmacology of neurological diseases focusing its scope on epilepsy, Alzheimer and Parkinson diseases, and neuropathic pain, even if other neurological diseases could have been analyzed. While the results of the studies discussed in this review point to a potential therapeutic benefit of chronopharmacology in neurological diseases, the field is still in its infancy. Studies including a sufficiently large number of patients and measuring gold standard markers of the circadian rhythmicity are still needed to evaluate the beneficial effect of administration times over the 24-hour day but also of clock modulating drugs.

Pharmacokinetics of exogenous melatonin in relation to formulation, and effects on sleep: A systematic review

There is conflicting evidence on the clinical efficacy of exogenous melatonin for the treatment of sleep disorders. This may be due to differences in the pharmacokinetic (PK) properties of melatonin formulations used in clinical trials. The aim of this systematic review was to understand the relationship between melatonin formulations and PK parameters and, where possible, the effects on sleep outcomes. To this purpose, we conducted a systematic review and nineteen papers were included. The studies included three melatonin transdermal formulation, thirteen oral formulations, one topical, two buccal, two intravenous and two nasogastric formulations. Seven studies investigated the effect of the melatonin formulation on sleep and six of them found a significant improvement in one or more sleep parameters. The potential for an improved controlled release formulation that delays maximum concentration (C_max) was identified. The different formulations and doses affect melatonin PK, suggesting that treatment efficacy maybe affected. Based on the current evidence, we are unable to provide recommendations of specific melatonin formulations and PK parameters for specific sleep disorders. Future studies should systematically investigate how different PK parameters of melatonin formulations affect efficacy treatment of sleep as well as circadian disorders.

Beneficial Effect of Melatonin on Motor and Memory Disturbances in 6-OHDA-Lesioned Rats

Previous evidence has shown a link between neurodegenerative diseases, including Parkinson's disease (PD), and melatonin. The data in the literature about the impact of the hormone under different experimental PD conditions are quite controversial, and its effect on memory impairment in the disease is very poorly explored. The current research was aimed at investigating the role of melatonin pretreatment on memory and motor behavior in healthy rats and those with the partial 6-hydroxydopamine (6-OHDA) model of PD. All rodents were pretreated with melatonin (20 mg/kg, intraperitoneally) for 5 days. At 24 h and 7 days after the first treatment for healthy rats, and at the second and third week post-lesion for those with PD, the animals were tested behaviorally (apomorphine-induced rotations, rotarod, and passive avoidance tests). The neurochemical levels of dopamine (DA), acetylcholine (ACh), noradrenaline (NA), and serotonin (Sero) in the brain were also determined. The results showed that in healthy animals, melatonin pretreatment had amnestic and motor-suppressive effects and did not change the levels of measured brain neurotransmitters. In animals with PD, melatonin pretreatment exerted a neuroprotective effect, manifested as a significantly decreased number of apomorphine-induced rotations, reduced number of falls in the rotarod test, and improved memory performance. The brain DA and ACh concentrations in the same animals were restored to the control levels, and those of NA and Sero did not change. Our results demonstrate a beneficial effect of melatonin on memory and motor disturbance in 6-OHDA-lesioned rats.

The Treatment of Sleep Dysfunction in Neurodegenerative Disorders

Sleep dysfunction is highly prevalent across the spectrum of neurodegenerative conditions and is a key determinant of quality of life for both patients and their families. Mounting recent evidence also suggests that such dysfunction exacerbates cognitive and affective clinical features of neurodegeneration, as well as disease progression through acceleration of pathogenic processes. Effective assessment and treatment of sleep dysfunction in neurodegeneration is therefore of paramount importance; yet robust therapeutic guidelines are lacking, owing in part to a historical paucity of effective treatments and trials. Here, we review the common sleep abnormalities evident in neurodegenerative disease states and evaluate the latest evidence for traditional and emerging interventions, both pharmacological and nonpharmacological. Interventions considered include conservative measures, targeted treatments of specific clinical sleep pathologies, established sedating and alerting agents, melatonin, and orexin antagonists, as well as bright light therapy, behavioral measures, and slow-wave sleep augmentation techniques. We conclude by providing a suggested framework for treatment based on contemporary evidence and highlight areas that may emerge as major therapeutic advances in the near future.

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.