Objective:Circadian rhythm disturbances are a frequent symptom in the dementias often leading to institutionalization. Several studies have proposed underlying brain pathology to be a major cause of these symptoms. Structural changes in the suprachiasmatic nucleus (SCN), proposed as the circadian pacemaker, have been related to circadian rhythm disturbances in patients with Alzheimer’s disease and other degenerative dementias. In vascular dementia, structural changes in other subcortical structures, proposed as sleep modulators, might be involved in rhythm disturbances. Design:We investigate whether the pattern of circadian rhythm disturbances is different in patients suffering from Alzheimer disease and patients suffering from vascular dementia. Telemetric motor activity was continuously recorded for three consecutive days after admission by using a wrist "actimeter". Materials and Methods:Circadian locomotor activity was recorded in patients with advanced Alzheimer disease (n = 5; average age =77.8 ± 5.6 years) and patients with severe vascular dementia (n = 5; average age = 82.6 ± 6.6 years) who were admitted to a geriatric psychiatry unit with clinical sleep disorders. Telemetric activity was continuously recorded for three consecutive days after admission. Results:In both groups, we found increased nocturnal activity and fragmentation of diurnal rhythm. The phase-delay of the rest-activity rhythm was delayed in patients with Alzheimer disease as compared to patients with vascular dementia (p < .05). Conclusion:In vascular dementia, changes in cortical and subcortical structures might lead to a fragmentation of the diurnal rhythm. In Alzheimer disease, structural changes in the SCN might in addition induce disturbance in a circadian pacemaker, leading to a phase shift in the circadian rhythm. The differential pattern of rhythm disturbance found in this study could be indicative of different processes involved in sleep disorders in the dementias.
Back to PD Thursday Poster Sessions
Back to The Eleventh International Congress