CIRCADIAN REST-ACTIVITY RHYTHM DISTURBANCES IN ALZHEIMERS-DISEASE

Previous studies showed circadian rhythm disturbances in patients with Alzheimer's disease, Rest-activity rhythm disturbances manifest thems elves through a fragmentation of the rhythm, a weak coupling with Zeit gebers, and high levels of activity during the night, The aim of the p resent study was to investigate which factors contribute to the presen ce of these disturbances, Therefore, several rest-activity rhythm, con stitutional, and environmental variables were assessed in a heterogene ous group of 34 patients with Alzheimer's disease, including presenile and senile patients living at home or in a nursing home, as well as i n II healthy controls, Circadian rest-activity rhythm disturbances wer e most prominent in institutionalized patients, Regression analyses sh owed the involvement of the following variables, First stability of th e rest-activity rhythm is associated with high levels of daytime activ ity and high levels of environmental light resulting from seasonal eff ects as well as from indoor illumination, Presenile onset contributed to instability of the rhythm. Second, fragmentation of periods of acti vity and rest is associated with low levels of daytime activity, and i s most prominent in moderately severe dementia, Third, night-time acti vity level is higher during the times of the year when the days are ge tting shorter and lower when the days are growing longer, These findin gs indicate that rest-activity rhythm disturbances may improve by incr easing environmental light and daytime activity, an assumption for whi ch empirical evidence has recently been published.