FRAGMENTATION OF ACTIVITY PERIODS IN ALZHEIMERS-DISEASE

Activity cycles were studied in 12 subjects clinically diagnosed with Alzheimer's disease. Subjects wore a movement sensor attached to a solid-state ambulatory monitor for 96 consecutive hours each. Varying degrees of fragmentation of the normal diurnal activity pattern were observed. Subject variables such as age, estimated duration of illness, cognitive ratings, and months since first admission were compared for degree of association with the movement data. Simple regression analyses showed that an estimate of the duration of illness was superior to others in predicting the degree of fragmentation in activity rhythms. Pathology in the suprachiasmatic nucleus of the hypothalamus is discussed in the light of these findings.