Temporal shifts in peak daily activity in Alzheimer's disease

Abstract

AbstractClinicians caring for Alzheimer patients have observed that some individuals show increased agitation, restlessness and confusion in the late afternoon, evening or at night. This has popularly been named ‘sundowning’ or ‘the sundowning syndrome’. Despite its obvious clinical importance, little research has been conducted to investigate abnormal activity patterns in patients with Alzheimer's disease. In this study, rest–activity patterns were examined using and electronic monitor with a movement sensor. Eighteen patients diagnosed with Alzheimer's disease were monitored for 48 consecutive hours each. Analyses indicated that some subjects showed increased activity around the time of sunset, and that these individuals were most likely to be in the middle stages of the disease. Subjects in the early stages of the disease showed peak activity before sunset, while those in the late stage showed peak activity after sunset. This progressive phase shift with increasing years of illness is a previously unreported phenomenon which may offer an explanation for the ‘sundowning syndrome’.