Suzuki K, et al. – This multicentre cross–sectional study was performed to examine the effect of sleep disturbances on clinical motor subtypes and disability in Parkinson’s disease (PD). A significant relationship was found between sleep disturbances and clinical motor subtypes. An increased number of sleep–related symptoms had an effect on disease–related disability.

• A cross-sectional relationship was reported between sleep-related symptoms and clinical motor subtypes (tremor dominant (TD); intermediate; postural instability and gait disturbances (PIGDs)) identified in a multicentre study, including 436 patients with PD and 401 age-matched controls.
• The authors evaluated PD-related sleep problems (PD-SP), excessive daytime sleepiness (EDS) and probable REM sleep behaviour disorder (pRBD) using the PD sleep scale (PDSS)-2, Epworth Sleepiness Scale (ESS) and RBD screening questionnaire-Japanese version (RBDSQ-J), respectively.

• In patients with Parkinson’s disease, PD-SP (PDSS-2 ≥18; 35.1% vs 7.0%), EDS (ESS ≥10; 37.8% vs 15.5%) and pRBD (RBDSQ-J ≥5; 35.1% vs 7.7%) were more common than in controls.
• The authors found no difference in the prevalence of restless legs syndrome between patients with PD and controls (3.4% vs 2.7%).
• The PIGD group had higher PDSS-2 and ESS scores than the TD group after adjusting for age, sex, disease duration, and Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) part III score.
• Among the TD, intermediate, and PIGD groups, the RBDSQ-J scores did not differ.
• Followed by the number of sleep-related symptoms (PD-SP, EDS, and pRBD), disease duration, MDS-UPDRS part III score, PIGD subtype, depression and MDS-UPDRS part IV score as significant predictors, a stepwise regression model predicting the MDS-UPDRS part II score identified the Hoehn and Yahr stage.