SUNDOWNING AND RATE OF DECLINE IN MENTAL FUNCTION IN ALZHEIMERS-DISEASE

Nocturnal exacerbation of disruptive behaviors has long been recognized as a common occurrence in Alzheimer's disease (AD), however the basis for such sleep disruption is poorly understood. In this study, caregivers of 60 patients with probable/possible AD were asked to indicate the typical temporal pattern of occurrence of any of seven disruptive behaviors over the 24-hour day. Patterns of disruptive behavior were defined as sundowning (afternoon, evening, or nocturnal exacerbation), morning exacerbation, and as a nontemporally specific pattern of behavioral disruption. About 28% of the patients were reported to sundown whereas 20% showed a pattern of morning exacerbation. Sundowning was unrelated to total score on the Mini-Mental State Exam (MMSE), however, sundowning was related to a faster rate of decline over time in selected mental functions on the MMSE. Specifically, declines in ideokinetic praxis abilities were related to sundowning.