Sex and onset-age-related features of excessive daytime sleepiness and night-time sleep in patients with Parkinson's disease

Sleep disturbance in rodent models and its sex-specific implications

Sleep disturbances, encompassing altered sleep physiology or disorders like insomnia and sleep apnea, profoundly impact physiological functions and elevate disease risk. Despite extensive research, the underlying mechanisms and sex-specific differences in sleep disorders remain elusive. While polysomnography serves as a cornerstone for human sleep studies, animal models provide invaluable insights into sleep mechanisms. However, the availability of animal models of sleep disorders is limited, with each model often representing a specific sleep issue or mechanism. Therefore, selecting appropriate animal models for sleep research is critical. Given the significant sex differences in sleep patterns and disorders, incorporating both male and female subjects in studies is essential for uncovering sex-specific mechanisms with clinical relevance. This review provides a comprehensive overview of various rodent models of sleep disturbance, including sleep deprivation, sleep fragmentation, and circadian rhythm dysfunction. We evaluate the advantages and disadvantages of each model and discuss sex differences in sleep and sleep disorders, along with potential mechanisms. We aim to advance our understanding of sleep disorders and facilitate sex-specific interventions.

Does Parkinson's disease affect sleep quality?

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disease that is linked to several motor and nonmotor symptoms, including sleep disturbances. Patient quality of life has been shown to be disproportionally impacted by disease.

OBJECTIVES

To investigate sleep quality among individuals with PD, and to assess the severity of sleep disturbances and their impact on daytime activities.

SUBJECTS AND METHODS

A case‒control with 44 patients with Parkinson's disease and 80 apparently healthy control participants was recruited from several hospitals and clinics. Each participant provided a thorough medical history and underwent a physical examination, and a questionnaire comprising the standard PSQI was used to assess sleep quality. Independent samples t test and Spearman's correlation analysis were used with a p value equal to or less than 0.05 which was considered significant.

RESULTS

The mean global PSQI score was 11.55 ± 4.412 for PD patients and 5.73 ± 3.22 for the control group with significant p value, Sleep latency onset was 75.57 min for PD patients and 22.81 min for the control group with significant p value. There was no significant correlation between age and other sleep-related variables. A total of 86.4% of patients with Parkinson's disease suffered from varying degrees of daytime dysfunction compared to 61.25% of the controls.

CONCLUSION

Parkinson's disease patients had poorer sleep quality than the controls. Age and sex were not found to be expected as a factor for sleep quality in patients with Parkinson's disease. Daytime dysfunction rates are high in patients with Parkinson's disease.

X-linked hydrocephalus genes: Their proximity to telomeres and high A + T content compared to Parkinson's disease

Proximity to telomeres (i) and high adenine and thymine (A + T) content (ii) are two factors associated with high mutation rates in human chromosomes. We have previously shown that >100 human genes when mutated to cause congenital hydrocephalus (CH) meet either factor (i) or (ii) at 91% matching, while two factors are poorly satisfied in human genes associated with familial Parkinson's disease (fPD) at 59%. Using the sets of mouse, rat, and human chromosomes, we found that 7 genes associated with CH were located on the X chromosome of mice, rats, and humans. However, genes associated with fPD were in different autosomes depending on species. While the contribution of proximity to telomeres in the autosome was comparable in CH and fPD, high A + T content played a pivotal contribution in X-linked CH (43% in all three species) than in fPD (6% in rodents or 13% in humans). Low A + T content found in fPD cases suggests that PARK family genes harbor roughly 3 times higher chances of methylations in CpG sites or epigenetic changes than X-linked genes.

Sex differences in alpha-synucleinopathies: a systematic review

Background

Past research indicates a higher prevalence, incidence, and severe clinical manifestations of alpha-synucleinopathies in men, leading to a suggestion of neuroprotective properties of female sex hormones (especially estrogen). The potential pathomechanisms of any such effect on alpha-synucleinopathies, however, are far from understood. With that aim, we undertook to systematically review, and to critically assess, contemporary evidence on sex and gender differences in alpha-synucleinopathies using a bench-to-bedside approach.

Methods

In this systematic review, studies investigating sex and gender differences in alpha-synucleinopathies (Rapid Eye Movement (REM) Behavior Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) from 2012 to 2022 were identified using electronic database searches of PubMed, Embase and Ovid.

Results

One hundred sixty-two studies were included; 5 RBD, 6 MSA, 20 DLB and 131 PD studies. Overall, there is conclusive evidence to suggest sex-and gender-specific manifestation in demographics, biomarkers, genetics, clinical features, interventions, and quality of life in alpha-synucleinopathies. Only limited data exists on the effects of distinct sex hormones, with majority of studies concentrating on estrogen and its speculated neuroprotective effects.

Conclusion

Future studies disentangling the underlying sex-specific mechanisms of alpha-synucleinopathies are urgently needed in order to enable novel sex-specific therapeutics.

Circadian disruption and sleep disorders in neurodegeneration

Disruptions of circadian rhythms and sleep cycles are common among neurodegenerative diseases and can occur at multiple levels. Accumulating evidence reveals a bidirectional relationship between disruptions of circadian rhythms and sleep cycles and neurodegenerative diseases. Circadian disruption and sleep disorders aggravate neurodegeneration and neurodegenerative diseases can in turn disrupt circadian rhythms and sleep. Importantly, circadian disruption and various sleep disorders can increase the risk of neurodegenerative diseases. Thus, harnessing the circadian biology findings from preclinical and translational research in neurodegenerative diseases is of importance for reducing risk of neurodegeneration and improving symptoms and quality of life of individuals with neurodegenerative disorders via approaches that normalize circadian in the context of precision medicine. In this review, we discuss the implications of circadian disruption and sleep disorders in neurodegenerative diseases by summarizing evidence from both human and animal studies, focusing on the bidirectional links of sleep and circadian rhythms with prevalent forms of neurodegeneration. These findings provide valuable insights into the pathogenesis of neurodegenerative diseases and suggest a promising role of circadian-based interventions.

Louis EK, Boeve BF, Savica R. Sleep Disorders in Early-Onset Parkinsonism: A Population-Based Study

BACKGROUND

Sleep disturbances are common in parkinsonian disorders; however, whether sleep disorders affect individuals with early-onset parkinsonism and whether they differ from individuals with typical-onset parkinsonism is unknown.

OBJECTIVE

To compare the prevalence and incidence of sleep disorders before and after parkinsonian motor symptom onset between individuals with early onset parkinsonism (age ≤50 at motor symptom onset) and typical-onset parkinsonism (age >50 at motor symptom onset).

METHODS

We used a population-based, 1991 to 2015 incident-cohort study of parkinsonism including 38 patients with early-onset and 1,001 patients with typical-onset parkinsonism. Presence or absence and type of sleep disorder as well as the relationship between motor and sleep symptoms were abstracted from the medical records. Rates of sleep disorders before and after onset of parkinsonism were compared with logistic regression and Cox proportional hazards models.

RESULTS

The prevalence of sleep disorders prior to the onset of parkinsonism in early vs. typical parkinsonism (24% vs. 16% p = 0.19) and incidence of sleep disorders after parkinsonism onset (5.85 cases per 100 person-years vs. 4.11 cases per 100 person-years; HR 1.15 95% CI: 0.74-1.77) were similar between the two groups. Early-onset parkinsonism had a higher risk for developing post-motor insomnia compared with typical-onset parkinsonism (HR 1.73, 95% CI: 1.02-2.93); the risk for developing all other sleep disorders considered was similar between groups.

CONCLUSION

Sleep disorders are common in individuals with early-onset parkinsonism and occur with similar frequency to those with typical-onset parkinsonism, except for insomnia, which was more frequent in the early-onset group.

Constructing prediction models for excessive daytime sleepiness by nomogram and machine learning: A large Chinese multicenter cohort study

Objective

Although risk factors for excessive daytime sleepiness (EDS) have been reported, there are still few cohort-based predictive models for EDS in Parkinson’s disease (PD). This 1-year longitudinal study aimed to develop a predictive model of EDS in patients with PD using a nomogram and machine learning (ML).

Materials and methods

A total of 995 patients with PD without EDS were included, and clinical data during the baseline period were recorded, which included basic information as well as motor and non-motor symptoms. One year later, the presence of EDS in this population was re-evaluated. First, the baseline characteristics of patients with PD with or without EDS were analyzed. Furthermore, a Cox proportional risk regression model and XGBoost ML were used to construct a prediction model of EDS in PD.

Results

At the 1-year follow-up, EDS occurred in 260 of 995 patients with PD (26.13%). Baseline features analysis showed that EDS correlated significantly with age, age of onset (AOO), hypertension, freezing of gait (FOG). In the Cox proportional risk regression model, we included high body mass index (BMI), late AOO, low motor score on the 39-item Parkinson’s Disease Questionnaire (PDQ-39), low orientation score on the Mini-Mental State Examination (MMSE), and absence of FOG. Kaplan–Meier survival curves showed that the survival prognosis of patients with PD in the high-risk group was significantly worse than that in the low-risk group. XGBoost demonstrated that BMI, AOO, PDQ-39 motor score, MMSE orientation score, and FOG contributed to the model to different degrees, in decreasing order of importance, and the overall accuracy of the model was 71.86% after testing.

Conclusion

In this study, we showed that risk factors for EDS in patients with PD include high BMI, late AOO, a low motor score of PDQ-39, low orientation score of MMSE, and lack of FOG, and their importance decreased in turn. Our model can predict EDS in PD with relative effectivity and accuracy.

Sex Differences in Parkinson’s Disease: From Bench to Bedside

Background: Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease and gender differences have been described on several aspects of PD. In the present commentary, we aimed to collect and discuss the currently available evidence on gender differences in PD regarding biomarkers, genetic factors, motor and non-motor symptoms, therapeutic management (including pharmacological and surgical treatment) as well as preclinical studies. Methods: A systematic literature review was performed by searching the Pubmed and Scopus databases with the search strings “biomarkers”, “deep brain stimulation”, “female”, “gender”, “genetic”, “levodopa”, “men”, “male”, “motor symptoms”, “non-motor symptoms”, “Parkinson disease”, “sex”, “surgery”, and “women”. Results: The present review confirms the existence of differences between men and women in Parkinson Disease, pointing out new information regarding evidence from animal models, genetic factors, biomarkers, clinical features and pharmacological and surgical treatment. Conclusions: The overall goal is to acquire new informations about sex and gender differences in Parkinson Disease, in order to develop tailored intervetions.