Sleep Quality and Cognitive Impairment in Patients with Parkinson's Disease in Iran

Objective: To evaluate the cognitive status and sleep quality and their association in patients with Parkinson's disease (PD). Materials and Methods: In this analytical cross-sectional study, 120 patients with PD were selected from 22-Bahman and 17-Shahrivar hospitals. Demographic information was recorded on a form and Parkinson's severity was determined using the Hoehn and Yahr scale (HY). Pittsburgh Sleep Quality Index (PSQI) and Epworth sleepiness scale (ESS) were used for the assessment of sleep quality and excessive daytime sleepiness, respectively. Cognitive status was assessed using the Montreal Cognitive Assessment questionnaire. Results: The mean age of patients with PD was 65.9 +/- 11.7 years, and 67.5% were men. Cognitive impairment was found in 113 (94.2%) patients, poor sleep quality in 87 (72.5%), and excessive daytime sleepiness in 27 (22.5%) patients. The mean PSQI and ESS scores were 9.03 +/- 4.70 and 7.38 +/- 3.73, respectively. There was a significant association between cognitive status and sleep quality, as well as daytime sleepiness (independent sample t-test, p<0.0001 for both). Conclusion: There is a significant association between cognitive impairment and poor sleep quality as well as excessive daytime sleepiness.