Original ArticleParkinson’s disease and REM sleep behavior disorder result in increased non-motor symptoms
Introduction
Parkinson’s disease (PD) is strongly associated with non-motor symptoms (NMS) including sleep disturbances, daytime sleepiness, dementia, fatigue, and depression [1]. In a large multicenter study, 99% of 1072 PD patients reported NMS [2]. NMS have a major negative impact on the lives of patients and their families, contributing to the severe disability these patients experience, impairing the quality of life (QOL), and even shortening life expectancy [3]. Some studies have suggested that NMS are more significant than motor symptoms when assessing caregiver distress, institutionalization rates, QOL, and overall economics of PD [1], [3], [4].
Rapid eye movement (REM)-sleep behavior disorder (RBD) is a parasomnia characterized by REM sleep without atonia (RSWA), that is, abnormal increase of muscle activity during REM sleep that is evident by phasic and/or tonic muscle activity on the electromyogram (EMG) channel on the overnight polysomnograph (PSG) recording. This loss of muscle atonia is typically described by patients as “acting out” their dreams. A high percentage of idiopathic RBD patients eventually develop neurodegenerative disease [5], and RBD has been recognized as a strong predictor of the development of synucleinopathies, including PD [6], [7].
RBD has been reported to affect up to 58% of PD patients [8], yet few studies have systematically assessed the relationship between RBD and NMS in PD. In a recent study, we reported that having PD and with multiple sleep disorders, was associated with increased NMS [9]. Those results showed that RBD is a significant predictor of increased NMS while controlling for other sleep disorders. The current study aimed to further assess and provide a more detailed understanding of the impact of having RBD on multiple NMS in patients with PD.
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Participants
A total of 183 PD patients were referred to the study by neurologists at the University of California, San Diego (UCSD) or by San Diego County community neurologists, volunteered after hearing a talk at support group meetings or responded to flyers and advertisements (Fig. 1). Among them, 106 patients met the inclusion/exclusion criteria (Table 1), agreed to participate, and consented for this study. However, seven patients dropped out prior to completing the overnight PSG, 12 were excluded
Results
A total of 86 PD patients (mean age = 67.2 ± 9.4 years; range: 47–89, 29f) participated in the study and were evaluated for RBD (Fig. 1). The majority of participants were Caucasian (90%), married (73%), and had at minimum an undergraduate degree (70%). There were no significant differences between yRBD and nRBD groups in any of the demographic variables except in the UPDRS total score (p = 0.017), UPDRS part 1 (p < 0.001) and part 2 (p = 0.02), and antidepressant use (p = 0.05; Table 2).
Discussion
This observational study assessed the complex relationship between RBD and NMS in PD. The results suggest that, after controlling for age and dopaminergic therapy, PD patients with RBD experienced more NMS than PD patients without RBD. Our results showed that PD patients with RBD reported more NMS on measures of depression, fatigue, sleep, and overall NMS. Our multivariate model of NMS in PD revealed a moderate effect size (R2 = 0.29), and moderate effect sizes were observed in the models of the
Support
NIA AG08415, NIH UL1RR031980, and Department of Veterans Affairs San Diego Center of Excellence for Stress and Mental Health (CESAMH).
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2014.04.009.
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