Rapid eye movement behavior disorder in drug-naïve patients with Parkinson’s disease

Non-motor symptoms of Parkinson`s disease-insights from genetics

Parkinson's disease (PD) is a neurodegenerative disorder characterized by both motor and non-motor symptoms (NMS). NMS including sleep disturbances, depression, anxiety, and constipation are diverse, can precede motor symptoms, and significantly impact patients` quality of life. The severity and type of NMS vary based on age, disease severity, and motor symptoms, and while some respond to dopaminergic treatments, others may be induced or exacerbated by such treatments. NMS also play a role in differentiating PD from drug-induced parkinsonism and are related to gait dysfunction in both early and advanced stages. Genetic factors play a significant role in the development of NMS in PD, with mutations in genes such as SNCA, LRRK2, PRKN, and GBA being associated with severe and early NMS. Familial studies and identification of susceptibility factors have provided insights into the genetic underpinnings of NMS in PD. Neurobehavioral changes, including cognitive decline, are common NMS in PD, and their genetic basis involves a spectrum of mutations shared with other neurodegenerative disorders. Further research is needed to elucidate the functional implications of these genetic factors and their contributions to the pathogenesis of NMS in PD.

The correlation between rapid eye movement sleep behavior disorder and the progress of Parkinson's disease: a systematic review and meta-analysis

Background

This meta-analysis was conducted to evaluate potential differences in symptoms between PD patients with or without RBD.

Methods

A systematic search was conducted in PubMed, Cochrane, Embase, and Web of Science databases (as of August 16, 2023), to identify relevant studies on PD and RBD. Statistical analysis was performed using Stata 15.0. Continuous variables were analyzed using the standardized mean difference (SMD) and 95% confidence interval (95% CI), while count data were assessed using the odds ratio (OR) and 95% CI as statistical effect sizes. Heterogeneity among all included studies was tested; for studies with low heterogeneity (I2 < 50%), a fixed-effects model was used to calculate statistical results. For studies with relatively high heterogeneity (I2 > 50%), a random-effects model was applied, followed by sensitivity and subgroup analyses to identify sources of heterogeneity.

Results

A total of 5,672 subjects were involved in this study. Compared to the NRBD group, the UPDRS-III score in the RBD group was significantly higher (SMD = 0.20, 95% CI: [0.11, 0.29], P < 0.001), and the Hoehn-Yahr score in the RBD group was also significantly higher (SMD = 0.29, 95% CI: [0.03, 0.55], P < 0.001). Patients with PD in the RBD group had more severe cognitive impairments than those in the NRBD group (SMD = -0.30, 95% CI: [-0.48, -0.11], P < 0.001). The incidence of hallucination in PD patients in the RBD group was 3.0 times that of the NRBD group (OR = 3.0, 95% CI: [2.15, 4.20], P = 0.110). PD patients in the RBD group also experienced more severe anxiety symptoms (SMD = 0.13, 95% CI: [-0.26, 0.51], P < 0.001), had higher scores in depression scales (SMD = 0.22, 95% CI: [0.02, 0.43], P < 0.001), and higher scores in sleep disorder scales than those in NRBD group (SMD = 0.10, 95% CI: [-0.11, 0.31], P < 0.001).

Conclusion

Results show PD patients with co-occurring RBD have more severe motor and non-motor symptoms likely due to overlapping affected regions in RBD and PD-related pathology, plus broader neurodegeneration seen in PD patients with RBD.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/#searchadvanced, identifier CRD42023476331.

Sleep and wakefulness disturbances in Parkinson's disease: A meta-analysis on prevalence and clinical aspects of REM sleep behavior disorder, excessive daytime sleepiness and insomnia

Sleep disorders (SDs) are common non-motor symptoms of Parkinson's disease (PD) with wide variability in their prevalence rates. The etiology of SDs in PD is multifactorial because the degenerative processes underlying the disease and their interaction with drugs and clinical features may promote REM sleep behavior disorder (RBD), excessive daytime sleepiness (EDS) and insomnia. Therefore, we designed a meta-analytic study to provide a reliable estimate of the prevalence and associated clinical and neuropsychiatric aspects of SDs in PD. A systematic literature search was performed up to February 2022. Pooled RBD prevalence was 46%, and its occurrence was associated with older age, lower education, longer disease duration, higher levodopa equivalent daily dose (LEDD), worse motor and autonomic manifestations, poorer quality of life and autonomy, and more severe neuropsychiatric symptoms. The pooled prevalence of EDS was 35% and was associated with older age, longer disease duration, worse motor and autonomic symptoms, higher LEDD, reduced autonomy, and more severe neuropsychiatric symptoms. Insomnia was reported in 44% of PD patients and was related to longer disease duration, higher LEDD, and more severe depression. SDs are associated with a more severe PD clinical phenotype; further studies should explore the pathophysiological mechanisms underlying SDs and develop targeted therapeutic strategies.

Blood neuroexosomal excitatory amino acid transporter-2 is associated with cognitive decline in Parkinson’s disease with RBD

Background

Rapid eye movement (REM) sleep behavior disorder (RBD) predicts cognitive decline in Parkinson’s disease (PD) patients without dementia. However, underlying mechanisms remain unknown. Accumulating studies suggest glutamatergic system dysregulation is associated.

Objective

To examine the effect of RBD on the rate of cognitive decline in PD patients and investigate whether plasma levels of the neuroexosomal vesicular glutamate transporter-1 (VGLUT-1) and excitatory amino acid transporter-2 (EAAT-2) are altered in PD patients with RBD.

Methods

This study included 157 newly diagnosed cognitive normal PD patients and 70 healthy controls (HCs). Based on one-night polysomnography recordings, the PD subjects were divided into PD with and without RBD (PD-RBD and PD-nRBD) groups. All participants received a complete clinical and neuropsychological evaluation at baseline. Plasma levels of neuroexosomal VGLUT-1 and EAAT-2 were measured by ELISA kits. After a 3-year follow-up, we evaluated baseline plasma levels of neuroexosomal glutamate transporters in each group as a predictor of cognitive decline using MoCA score changes over 3 years in regression models.

Results

Plasma levels of neuron-derived exosomal EAAT-2 and VGLUT-1 were significantly lower in PD patients than in HCs. Plasma levels of neuroexosomal EAAT-2 were significantly lower in PD-RBD than PD-nRBD group at baseline. At the 3-year follow-up, PD-RBD patients presented greater cognitive decline. Lower baseline blood neuroexosomal EAAT-2 predicted cognitive decline over 3 years in PD-RBD patients (β = 0.064, P = 0.003).

Conclusion

These findings indicate that blood neuroexosomal EAAT-2 is associated with cognitive decline in PD with RBD.

Cerebrospinal Fluid TNF-α and Orexin in Patients With Parkinson's Disease and Rapid Eye Movement Sleep Behavior Disorder

Background

Parkinson's disease (PD) pathological changes begin before motor symptoms appear. Rapid eye movement sleep behavior disorder (RBD) has the highest specificity and predictive value of any marker of prodromal PD. Tumor necrosis factor α (TNF-α) plays a part in the pathology of PD and disease conversion in isolated RBD (iRBD). TNF can also directly impair the hypocretin system in mice in vivo. As a result, we intend to investigate the effect of TNF-α on orexin levels in PD patients with RBD.

Method

Participants were recruited from the Department of Neurology of Xuanwu Hospital, Capital Medical University to engage in assessments on motor symptoms, sleep, cognition, etc. Then we collected blood and cerebrospinal fluid of all patients and 10 controls' cerebrospinal fluid. The levels of TNF-α in the serum and cerebrospinal fluid, as well as the level of orexin in the cerebrospinal fluid, were measured in the patients.

Results

The difference in TNF- levels in cerebrospinal fluid and serum between the three groups were not statistically significant. The levels of orexin in the three groups were not significantly lower than in the control group. UPDRS-III scores were significantly higher in the PD+RBD and PD-RBD groups than in the iRBD group. There was no statistically significant difference in H-Y stages, PSQI, or ESS scores between the PD+RBD and PD-RBD groups.

Conclusion

Our findings suggest that TNF-α may not have a significant effect on the orexinergic system in patients with Parkinson's disease and iRBD. As a result, it is necessary to investigate the changes in TNF-α and orexin levels in different disease stages and to enlarge the sample size to determine whether TNF-α affects the function of the orexin system, which may be related to the occurrence of RBD and disease progression in Parkinson's disease.

Clinical and imaging evidence of brain-first and body-first Parkinson's disease

Braak's hypothesis has been extremely influential over the last two decades. However, neuropathological and clinical evidence suggest that the model does not conform to all patients with Parkinson's disease (PD). To resolve this controversy, a new model was recently proposed; in brain-first PD, the initial α-synuclein pathology arise inside the central nervous system, likely rostral to the substantia nigra pars compacta, and spread via interconnected structures - eventually affecting the autonomic nervous system; in body-first PD, the initial pathological α-synuclein originates in the enteric nervous system with subsequent caudo-rostral propagation to the autonomic and central nervous system. By using REM-sleep behavior disorder (RBD) as a clinical identifier to distinguish between body-first PD (RBD-positive at motor symptom onset) and brain-first PD (RBD-negative at motor symptom onset), we explored the literature to evaluate clinical and imaging differences between these proposed subtypes. Body-first PD patients display: 1) a larger burden of autonomic symptoms - in particular orthostatic hypotension and constipation, 2) more frequent pathological α-synuclein in peripheral tissues, 3) more brainstem and autonomic nervous system involvement in imaging studies, 4) more symmetric striatal dopaminergic loss and motor symptoms, and 5) slightly more olfactory dysfunction. In contrast, only minor cortical metabolic alterations emerge before motor symptoms in body-first. Brain-first PD is characterized by the opposite clinical and imaging patterns. Patients with pathological LRRK2 genetic variants mostly resemble a brain-first PD profile whereas patients with GBA variants typically conform to a body-first profile. SNCA-variant carriers are equally distributed between both subtypes. Overall, the literature indicates that body-first and brain-first PD might be two distinguishable entities on some clinical and imaging markers.

Prevalence and profile of nocturnal disturbances in Chinese patients with advanced-stage Parkinson's disease: a cross-sectional epidemiology study

Background

The impact of nocturnal disturbance (ND) in Parkinson’s disease on quality of life of patients in Western Countries is increasingly understood. Our study aimed to investigate ND prevalence and its quality of life impact in patients with advanced Parkinson’s disease in China.

Methods

In a multicenter, tertiary-care hospital, outpatient-based, cross-sectional study, patients with advanced Parkinson’s disease (Modified Hoehn & Yahr [H&Y] Stage II–IV with ≥3 h awake “off” time/day) from 10 tertiary hospitals throughout China completed the Parkinson’s Disease Sleep Scale-2 (PDSS-2) and Parkinson’s Disease Questionnaire-39 (PDQ-39). The primary endpoint was the percentage of patients with significant ND (PDSS-2 total score ≥ 15). Additional endpoints were demographic and clinical characteristics, PDSS-2 and PDQ-39 total and subscale scores, correlation between PDSS-2 and PDQ-39, and risk factors for ND and higher PDSS-2 or PDQ-39 scores.

Results

Of 448 patients analyzed (mean age 63.5 years, 47.3% female), 70.92% (95% confidence interval: 66.71, 75.13) had significant ND. Presence of ND and higher PDSS-2 scores were associated with longer disease duration and higher H&Y stage. Presence of ND was also associated with more awake “off” time/day and female sex. PDQ-39 scores were significantly worse for patients with ND versus those without ND; worse scores were associated with more awake “off” time/day, female sex, and higher H&Y stage. PDSS-2 and PDQ-39 total scores were associated: Pearson correlation coefficient 0.62 (p < 0.001).

Conclusions

In China, ND was highly prevalent in patients with advanced Parkinson’s disease and adversely impacted quality of life. This study highlights the importance of early diagnosis and optimized management of ND in patients with Parkinson’s disease in China.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02217-5.

Sleep Disorders and Cognitive Dysfunctions in Parkinson's Disease: A Meta-Analytic Study

A relationship between sleep disorders and cognitive dysfunctions was reported in Parkinson's Disease (PD), however, some studies did not confirm the link. A meta-analytic study was performed to investigate the relationship between sleep disorders and cognitive dysfunctions, and to clarify the evolution of cognitive status in PD patients with sleep disorders.The systematic literature search was performed up to November 2020 using PubMed, Scopus, and PsycINFO databases. We included studies published in peer-reviewed journals in English providing results about neuropsychological comparison between patients with or without sleep disorders. Meta-analysis on cross-sectional data included 54 studies for REM Sleep Behavior Disorder (RBD), 22 for Excessive Daytime Sleepiness (EDS), 7 for Obstructive Sleep Apnea (OSA), 13 for Restless Legs Syndrome (RLS), and 5 for insomnia, the meta-analysis on longitudinal data included 7 studies.RBD was related to deficits of global cognitive functioning, memory, executive functions, attention/working memory, language, and visuospatial abilities. EDS was associated with deficits of global cognitive functioning and attention and working memory abilities, whereas RLS and OSA were related to global cognitive dysfunction. Moreover, we revealed that PD patients with RBD and those with EDS performed worse than PD patients without sleep disorders at follow-up rather than baseline evaluation. Our results suggest that sleep disorders are associated with cognitive deficits supporting indirectly that these, especially the REM Sleep Behavior Disorder, reflect abnormalities of frontal networks and posterior cortical areas. Sleep disorders in patients with PD seem to also increase the risk for long-term cognitive decline.

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

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

Sleep Disturbances and Associated Factors in Drug-Naïve Patients with Parkinson's Disease

PURPOSE

Sleep disturbance is one of the common symptoms in Parkinson's disease (PD). The study of sleep disturbance used to concentrate on treated PD. This study aimed to investigate the factors that are associated with the sleep quality of drug-naïve patients with PD.

PATIENTS AND METHODS

All participants were interviewed using a standard questionnaire to collect basic information. PD severity, depression symptoms, anxiety symptoms, sleep quality, cognitive status, life quality, and the presence of rapid eye movement (REM) sleep behavior disorder (RBD) and minor hallucination were assessed using corresponding rating scales. The patients with a Pittsburgh Sleep Quality Index score ≤6 fell into the poor sleep group, and those with REM Sleep Behavior Disorder Screening Questionnaire score ≥5 were considered to have probable RBD.

RESULTS

Seventy drug-naive patients with PD and 30 healthy controls matched for age, sex, and education were recruited. Up to 41.4% of the patients suffered from sleep disturbance, and 24.3% of the patients had RBD. Poor sleepers were more likely to have left-side predominant motor symptoms. Compared with good sleepers, poor sleepers, particularly female patients, had more burden in the aspect of anxiety and depression. RBD was associated with more nonmotor symptoms, poor sleep quality, bad performance in cognition orientation domain, anxiety, depression, presence of minor hallucination, and poor life quality.

CONCLUSION

Sleep disturbances are common in drug-naïve PD and require wide attention. Motor symptom laterality and gender difference in mood are associated with sleep quality. Depression, anxiety, and RBD are highly related to sleep disturbance. RBD has many comorbidities, which can influence the cognitive function and life quality of the patients.

Association Between REM Sleep Behavior Disorder and Cognitive Dysfunctions in Parkinson's Disease: A Systematic Review and Meta-Analysis of Observational Studies

Background: Rapid eye movement sleep behavior disorder (RBD) is thought to be a prodromal symptom of Parkinson's disease (PD). RBD is also thought to be involved in cognitive decline and dementia in PD. In PD, although the relationship between RBD and cognitive dysfunctions was confirmed by considerable studies, whether RBD was associated with distinct types of cognitive defects is worth of study. Objectives: This systematic review summarizes the evidence relating to cognitive dysfunction in PD patients with RBD (PD-RBD) and those without and explores their specificity to cognitive domains. Methods: A meta-analysis using a random-effects model was performed for 16 different cognitive domains, including global cognitive function, memory (long-term verbal recall, long-term verbal recognition, long-term visual recall, short-term spatial recall, and short-term verbal recall), executive function (general, fluid reasoning, generativity, shifting, inhibition, and updating), language, processing speed/complex attention/working memory, visuospatial/constructional ability, and psychomotor ability. The cognitive difference between the groups of patients was measured as a standardized mean difference (SMD, Cohen's d). PD-RBD patients were classified into Confirmed-RBD (definite diagnosis with polysomnography, PSG) and Probable-RBD (without PSG re-confirmation). In some domains, RBD patients could not be analyzed separately due to the exiguity of primary studies; this analysis refers to such RBD patients as "Mixed-RBD." Results: Thirty-nine studies with 6,695 PD subjects were finally included. Confirmed-RBD patients showed worse performance than those without in global cognitive function, long-term verbal recall, long-term verbal recognition, generativity, inhibition, shifting, language, and visuospatial/constructional ability; Probable-RBD, in global cognitive function and shifting; and Mixed-RBD, in long-term visual recall, short-term spatial recall, general executive function, and processing speed/complex attention/working memory. Conclusion: This meta-analysis strongly suggests a relationship between RBD, Confirmed-RBD in particular, and cognitive dysfunctions in PD patients. Early and routine screening by sensitive and targeted cognitive tasks is necessary for all PD-RBD patients because it may offer the therapeutic time window before they evolve to irreversible dementia.

Non-motor symptoms are associated with REM sleep behavior disorder in Parkinson's disease: a systematic review and meta-analysis

OBJECTIVE

Parkinson's disease (PD) is usually accompanied by rapid eye movement sleep behavior disorder (RBD). A systematic review has concluded that motor manifestations are associated with RBD in PD patients, but whether the same is true of non-motor symptoms is unclear.

METHODS

A systematic review and meta-analysis was conducted by searching studies related to PD and RBD in PubMed, Web of Science, Embase, and Cochrane databases. Data were pooled where appropriate and used to calculate odds ratios (ORs), mean differences (MDs), or standardized mean differences (SMDs) with 95% confidence intervals (CI). Heterogeneity was assessed using the I² statistic.

RESULTS

PD patients with RBD were more likely to be male (OR 1.26, 95% CI 1.14-1.40) and older (MD 1.70 years, 95% CI 1.24-2.16) than those of patients without RBD. Patients with RBD were at a higher risk of non-motor symptoms such as constipation (OR 1.94, 95% CI 1.57-2.38), hallucination (OR 2.62, 95% CI 2.01-3.41), depression (SMD 0.39, 95% CI 0.25-0.53), and cognitive impairment (SMD - 0.29, 95% CI - 0.42 to - 0.17) based on standardized questionnaire scores. Similarly, PD patients with RBD suffered more severe motor symptoms and required higher doses of levodopa therapy.

CONCLUSIONS

The available evidence suggests that PD patients with RBD suffer severer non-motor and motor symptoms than those without RBD. A potential explanation is that PD patients with RBD present more diffuse neurodegeneration.

Increased rapid eye movement density in Chinese patients with Parkinson's disease and RBD

OBJECTIVE

Impaired rapid eye movement sleep is common among patients with Parkinson's disease (PD). However, information on rapid eye movement density (REM) among PD patients is currently lacking. The current study sought to characterize REM density in PD patients and to examine the associations between REM density sleep parameters and clinical manifestations.

PARTICIPANTS AND METHODS

We retrospectively recruited 172 PD patients. All participants were assessed with a two-night polysomnography, and REM density was calculated. Clinical assessments were completed in PD patients before polysomnography.

RESULTS

Rapid eye movement sleep behavior disorder (RBD) was observed in 93 patients (54.1%). The disease duration, UPDRS part III score, Hoehn and Yahr (H-Y) stage, and HAMA, HAMD, PDQ-39 scores, and REM density in the Parkinson's disease patients with rapid eye movement sleep behavior disorder (RBD) were significantly higher than in the patients without RBD (P < 0.05). However, NREM sleep stage 3 time (N3 time) and percentage of N3 time of total sleep time (N3%) were significantly lower in the RBD patients than in the patients without RBD (P < 0.05). The forward binary logistic regression model showed that REM density, UPDRS-III score, and N3 sleep time were associated with RBD in the PD patients.

CONCLUSIONS

Our results confirm the high prevalence of RBD in patients with PD. Increased REM density was the main risk factor of RBD.

Polysomnographic predictors of sleep, motor and cognitive dysfunction progression in Parkinson's disease: a longitudinal study

OBJECTIVE

To assess the predictive value of polysomnographic (PSG) data in the prospective assessment of cognitive, motor, daytime and nighttime sleep dysfunction in Parkinson's Disease (PD) patients.

METHODS

PD patients were assessed at baseline with video-PSG and with cognitive (MoCA), Sleep (SCOPA-Sleep Nighttime and Daytime scores) and Motor (UPDRSIII) function scales at both baseline and four years later. Linear regression analysis was used to assess the relation between PSG variables at baseline and change in symptoms scores.

RESULTS

We included a total of 25 patients, 12 with rapid eye movement (REM) sleep behavior disorder (RBD) (in 8 PSG was inconclusive, due to lack of REM sleep). MoCA scores decreased significantly at follow-up, while SCOPA-Sleep Daytime and SCOPA-Sleep Nighttime and UPDRSIII did not vary. Lower N3 percentage at baseline was significantly associated with MoCA decrease. Higher Periodic Limb Movements in Sleep index (PLMS) and the presence of RBD were significantly associated with SCOPA daytime score increase. Higher global severity of RBD, tonic RSWA and total number of motor events during REM sleep were associated with SCOPA Nighttime score increase.

CONCLUSIONS

The present work suggests that PSG data could be useful for predicting PD cognitive and sleep dysfunction progression. Reduced SWS could predict deterioration of cognitive function, while baseline PLMS could be useful to predict worsening of daytime sleep dysfunction. Severity of RBD could be used for estimating nighttime sleep symptoms progression.

Sleep in Parkinson's disease: A systematic review and meta-analysis of polysomnographic findings

Polysomnographic studies have been conducted to explore sleep changes in Parkinson's disease (PD), but the relationships between sleep disturbances and PD are imperfectly understood. We conducted a systematic review of the literature exploring polysomnographic differences between PD patients and controls in EMBASE, MEDLINE, All EBM databases, CINAHL, and PsycIFNO. 67 studies were identified for systematic review, 63 of which were used for meta-analysis. Meta-analyses revealed significant reductions in total sleep time, sleep efficiency, N2 percentage, slow wave sleep, rapid eye movement sleep (REM) percentage, and increases in wake time after sleep onset, N1 percentage, REM latency, apnea hypopnea index, and periodic limb movement index in PD patients compared with controls. There were no remarkable differences in sleep continuity or sleep architecture between PD patients with and without REM sleep behavior disorder (RBD). Our study suggests that PD patients have poor sleep quality and quantity. Sex, age, disease duration, presence of RBD, medication status, cognitive impairment, and adaptation night are factors that contributed to heterogeneity between studies.