Circadian rhythm abnormalities of wrist activity of institutionalized dependent elderly persons with dementia

Background The study objective was to clarify the descriptive characteristi cs of circadian rhythm abnormalities of wrist activity of the institutional ized elderly with dementia. Methods. We studied 82 elderly persons with dementia who were institutional ized in a long-term medical fare facility. The ambulatory continuous monito ring of their wrist activity was conducted for 7 days at 1-minute intervals . The time series data were analyzed using the double-plotted chronogram, s pectral analysis was performed using the fast Fourier transformation and pe riodogram 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 abnor malities were classified into four categories: severely impaired circadian rhythm type with net boundary between day and night, free-running rhythm ty pe, decreased circadian amplitude type, and accen tuation of ultradian rhyt hm type. Conclusion. This four-category classification system provides a scientific approach for studying the mechanisms of circadian activity rhythm abnormali ties of elderly persons with dementia.