New approach for the early detection of dementia by recording in-house activities.

People with dementia often have low physical activity and some sleep problems. This study focused on daily life activities and sleeping conditions, and examined the use of these parameters for detecting dementia. Five passive infrared (IR) sensors were installed in each of 14 subject's houses. Each patient lived alone. The subjects' in-house movements were recorded by the passive IR sensor for approximately 3 months (average, 78 days). Based on these records, the following parameters of life activities were assessed: (1) the number of outings, (2) total sleep time, (3) number of sleep interruptions, and (4) sleep rhythm. Subjects with impaired cognition (Mini Mental State Examination [MMSE] < 24) had a significantly lesser number of outings (p = 0.001) and a tendency toward a shorter sleep time (p = 0.054) in comparison with control subjects (MMSE >or= 24). These results suggest that the monitoring of life activities by using passive infrared sensors could be an efficient method for detecting dementia.