Nonlinear indices of circadian changes in individuals with dementia and aggression.

Nonlinear analyses of actigraphy data were utilized to investigate circadian rest-activity system motor control in nursing-home residents with dementia and with/without aggressive behavior (AB). Significant differences observed between groups in measures of approximate entropy (ApEn) and fractal dimension (FD). ApEn and FD are sensitive to detecting and characterizing discrete changes in central motoric control and temporality of behaviors in dementia. Findings may inform understanding of clinical heterogeneity and possible physiologic sub-classifications of Alzheimer’s dementia.