BACKGROUND: The study objective was to clarify the descriptive characteristics of circadian rhythm abnormalities of wrist activity of the institutionalized elderly with dementia. METHODS: We studied 82 elderly persons with dementia who were institutionalized in a long-term medical care facility. The ambulatory continuous monitoring of their wrist activity was conducted for 7 days at 1-minute intervals. The time series data were analyzed using the double-plotted chronogram, spectral analysis was performed using the fast Fourier transformation and periodogram analysis was performed as well. RESULTS: The frequency of circadian rhythm abnormalities of wrist activity rhythm in elderly persons with dementia was 57.3% (47 out of 82). The abnormalities were classified into four categories: severely impaired circadian rhythm type with no boundary between day and night, free-running rhythm type, decreased circadian amplitude type, and accentuation of ultradian rhythm type. CONCLUSION: This four-category classification system provides a scientific approach for studying the mechanisms of circadian activity rhythm abnormalities of elderly persons with dementia.
BACKGROUND: The study objective was to clarify the descriptive characteristics of circadian rhythm abnormalities of wrist activity of the institutionalized elderly with dementia. METHODS: We studied 82 elderly persons with dementia who were institutionalized in a long-term medical care facility. The ambulatory continuous monitoring of their wrist activity was conducted for 7 days at 1-minute intervals. The time series data were analyzed using the double-plotted chronogram, spectral analysis was performed using the fast Fourier transformation and periodogram analysis was performed as well. RESULTS: The frequency of circadian rhythm abnormalities of wrist activity rhythm in elderly persons with dementia was 57.3% (47 out of 82). The abnormalities were classified into four categories: severely impaired circadian rhythm type with no boundary between day and night, free-running rhythm type, decreased circadian amplitude type, and accentuation of ultradian rhythm type. CONCLUSION: This four-category classification system provides a scientific approach for studying the mechanisms of circadian activity rhythm abnormalities of elderly persons with dementia.