1142 CIRCADIAN REST-ACTIVITY RHYTHMS AND COGNITIVE FUNCTION IN PARKINSON’S DISEASE

Abstract

Introduction: There is accruing evidence that circadian rhythms are disrupted in Parkinson's disease (PD). Because circadian function is associated with cognition in the general population, we hypothesized that circadian disruption is a mechanism for cognitive impairment in PD. Method(s): We used nonparametric circadian rhythm analysis (NPCRA) to compare actigraphy-derived rest-activity circadian function, over the course of 7 days, in 35 non-demented individuals with idiopathic PD and 15 matched healthy control participants. Within the PD group, we then examined the separate contributions of circadian robustness and sleep efficiency to cognition as measured with standard neuropsychological tests. Result(s): The PD participants exhibited a lower relative amplitude in their daily/circadian rest-activity patterns than the control group. For the PD group, less stable day-to-day rest-activity patterns predicted poorer executive and visuospatial functioning and slower psychomotor speed. Hierarchical regressions showed that circadian stability significantly contributed to variance in each of these cognitive domains above and beyond the contributions of objective sleep quality. Whereas sleep efficiency predicted executive function (accounting for 18.3% of the variance) but did not predict psychomotor or visuospatial performance, circadian stability significantly predicted performance in all three domains, uniquely accounting for 14.4% to 17.4% of the variance. Conclusion(s): Our findings indicate that rest-activity circadian rhythms are disrupted in PD relative to matched healthy adults, and that circadian dysfunction is a potential mechanism for cognitive impairment in PD.