Characteristics of sleep disturbances in Japanese patients with Parkinson's disease. A study using Parkinson's disease sleep scale.

The present multicenter cross-sectional study was performed using semistructured questionnaires to determine the contributing factors of sleep disturbances in Japanese patients with Parkinson's disease (PD). We used the Parkinson's disease sleep scale (PDSS, Japanese version). All data were obtained by means of interviewed questionnaire and physical examination by neurologists. The study was carried out between April 2005 and December 2005 at eight university hospitals and affiliated facilities in the Kanto area of Japan. A total of 188 (85 men and 103 women) PD patients and 144 controls (64 men and 80 women) were included. Stepwise regression analysis identified complications of treatment, depression, age, and disease duration as significant risk factors of sleep disturbances in PD. Significant differences in total PDSS score were observed between Hoehn & Yahr (H&Y) Stages 1 and 4, between H&Y Stages 2 and 4, and between H&Y stages 3 and 4 (Bonferroni test). The results of this survey suggested that complications due to treatment (dyskinesia, wearing off, on-off), depressive state, and disease stage are significant determinants of sleep disorders in Japanese patients with PD. We speculate that the reduction of neurotransmitters involved in the sleep-wakefulness mechanism and degeneration of neurons progress together in parallel with deterioration of motor function.