[Rest-activity and body-temperature rhythm disorders in elderly patients with dementia--senile dementia of Alzheimer's type and multi-infarct dementia].

We simultaneously monitored rest-activity and body temperature (BT) rhythm in demented patients with sleep and behavior disorders using ambulatory wrist-worn actigraph and long-term monitoring system for 5-7 consecutive days. Subjects consisted of 19 patients with senile dementia of Alzheimer's type (SDAT) (M/F = 7/12, mean age = 71.7 years), 16 patients with multi-infarct dementia (MID) (M/F = 9/7, mean age = 75.2 years) and 9 normal controls (M/F = 4/5, mean age = 70.4 years). Both dementia groups showed a significant increase in percentage of nighttime activity. In the SDAT group, a significant positive correlation between the degree of dementia and total activity was observed, but not observed in the MID group. A significant high amplitude of BT rhythm was observed in the SDAT group comparing that in the MID or the control group. These findings indicate that the SDAT patients had a disrupted rest-activity rhythm with the severity of intellectual deterioration and increased night activity, while the circadian BT rhythm was remarkably well preserved, i.e. there was a dissociation between rest-activity and BT rhythms in the SDAT group. On the other hand, the disruption of the rest-activity and BT rhythm in the MID patients was characterized by a concomitant decrease of amplitude, which seems to have no relation with the severity of dementia. Different mechanisms could be involved in characteristic disruption of the circadian rhythms in the 2 dementia groups.