Modeling cortisol daily rhythms of family caregivers of individuals with dementia: Daily stressors and adult day services use

Objectives: The study examined the typical diurnal cortisol trajectory and its differential associations with an intervention, the adult day services (ADS) use, among a sample of family caregivers who experienced high levels of daily stress. Method: On hundred and sixty-five caregivers of individuals with dementia completed an 8-day diary on daily stressors, positive events, sleep quality, and ADS use. The caregivers also provided five saliva samples on each diary day. Daily cortisol trajectories were modeled as a function of time elapsed since awakening, and three spline growth curve models were fit to the cortisol data. Based on the best-fitting linear spline model, the effect of daily ADS use was examined at both daily and person levels. Covariates included daily experiences and other caregiving characteristics. Results: On ADS days, caregivers had a steeper cortisol awakening response (CAR) slope and a steeper morning decline. ADS use remained significant after controlling for covariates at both daily and person levels. Discussion: The findings suggested potential biophysiological benefits of daily ADS use for a sample that was under chronic stress and high levels of daily stress