Abstract
Purpose: Parkinson's disease (PD) patients frequently present with sleep disorders. This study was designed to assess the impact of nonmotor symptoms (NMSs) on sleep quality in early-stage PD patients with and without cognitive dysfunction.Materials and Methods: A sample of 389 early-stage PD patients (modified Hoehn and Yahr score ≤ 2.5, duration ≤ 5 years) was recruited for the present study. The Non-Motor Symptoms Questionnaire (NMS-Quest) was used to screen for global NMSs. Depressive symptoms were assessed using the Hamilton Rating Scale for Depression (HAMD). PD motor symptoms were measured with the Unified PD Rating Scale (UPDRS), part III. The Montreal Cognitive Assessment (MoCA) was used to evaluate global cognitive status, and the PD Sleep Scale (PDSS) was used to quantify sleep quality. Polysomnography (PSG) was used for objective assessment of sleep.Results: In our sample, approximately one-quarter of the PD patients suffered from sleep disturbances (23.7%). Our results also confirmed the high prevalence of cognitive dysfunction in patients with PD (39.8%). In patients with cognitive dysfunction, higher percentage of sleep disorders (34.8 vs. 16.2%, P < 0.01) was observed. They also with lower PDSS score, sleep efficiency (SE) and longer sleep lantency (SL) and wake after sleep onset (WASO) (All P < 0.05). In total, the patients who suffered from NMSs, such as depressive symptoms, anxiety symptoms, urinary tract symptoms and hallucinations/delusions, had poorer sleep quality. Better cognition may predict better sleep quality. In patients with cognitive dysfunction, the NMS-Hallucinations/delusions score was the most important risk factor for sleep disorders. In patients without cognitive dysfunction, NMSs such as anxiety and cognition and medication were related to sleep disorder.Conclusions: NMSs in early-stage PD are highly associated with and are determinants of subjective sleep quality. Future studies should focus on elucidating the pathophysiology of these symptoms.
Highlights
Parkinson’s disease (PD) is the second most common neurodegenerative disease in the Chinese population aged over 65 years [1]
Our results confirmed the high prevalence of cognitive dysfunction in patients with PD (39.8%)
Future studies should focus on elucidating the pathophysiology of these symptoms
Summary
Parkinson’s disease (PD) is the second most common neurodegenerative disease in the Chinese population aged over 65 years [1]. PD is mainly defined by motor symptoms such as tremor, rigidity, bradykinesia, and postural instability. Damage to the dopaminergic system plays an important role in the motor symptoms of PD patients. The pathological course of PD has been found to involve the serotoninergic, noradrenergic, and cholinergic systems in addition to the dopaminergic system [2]. Dysfunction in these nondopaminergic systems may play a crucial role in the development of nonmotor symptoms (NMSs), including neuropsychiatric manifestations, autonomic and sensory dysfunctions, and sleep disorders [3]. NMSs of PD can precede the emergence of typical motor symptoms and the diagnosis of PD by several years
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