Symptoms of REM sleep behavior disorder (RBD) may be a sign of or risk factor for greater impairment of executive functions in people with Parkinson’s disease. Individuals with PD and probable RBD (n = 19) had poorer performance on cognitive flexibility tasks compared with individuals with PD and no RBD symptoms (n = 31). Cognitive flexibility tasks included word reading (P < .013), switching verbal fluency (P < .024), and category verbal fluency (P < .016).
Individuals with PD with or without RBD symptoms had poorer attention (P < .01), visuospatial skills (P < .011), and working memory (P < .021) compared to healthy participants (n = 47). Severity of PD did not differ between those with or without RBD symptoms.
For this study, RBD symptoms were assessed with the REM Sleep Behavior Disorder Screening Questionnaire, and a score of more than 5 was considered probable RBD. Severity of PD was measured using a modified Hoehn-Yahr Scale and duration of PD. Cognitive functions were measured with the Delis-Kaplan Executive Function System subtests, working memory as accuracy on 2- and 3-back tests, visuospatial skills with the Benton Judgment of Line Orientation. Differences between groups were analyzed with Mann-Whitney U- and t-tests.
These data support the hypothesis that RBD, when present in those with PD, may represent a more severe prognosis.
Michelle L. Dougherty, MD, FAAN, FAES
Margaret Yu, MD; Christian Sikorski, MD; Craig M. Horbinski, MD; and Rimas V. Lukas, MD