24 h Rest/Activity Rhythms in Older Adults with Memory Impairment: Associations with Cognitive Performance and Depressive Symptomatology

Abstract Little is known about links of circadian rhythm alterations with neuropsychiatric symptoms and cognition in memory impaired older adults. Associations of actigraphic rest/activity rhythms (RAR) with depressive symptoms and cognition are examined using function‐on‐scalar regression (FOSR). Forty‐four older adults with memory impairment (mean: 76.84 ± 8.15 years; 40.9% female) completed 6.37 ± 0.93 days of actigraphy, the Beck depression inventory‐II (BDI‐II), mini‐mental state examination (MMSE) and consortium to establish a registry for Alzheimer's disease (CERAD) delayed word recall. FOSR models with BDI‐II, MMSE, or CERAD as individual predictors adjusted for demographics (Models A1‐A3) and all three predictors and demographics (Model B). In Model B, higher BDI‐II scores are associated with greater activity from 12:00–11:50 a.m., 2:10–5:50 p.m., 8:40–9:40 p.m., 11:20–12:00 a.m., higher CERAD scores with greater activity from 9:20–10:00 p.m., and higher MMSE scores with greater activity from 5:50–10:50 a.m. and 12:40–5:00 p.m. Greater depressive symptomatology is associated with greater activity in midafternoon, evening, and overnight into midday; better delayed recall with greater late evening activity; and higher global cognitive performance with greater morning and afternoon activity (Model B). Time‐of‐day specific RAR alterations may affect mood and cognitive performance in this population.