The Impact of Average and Daily Rumination on Diurnal Cortisol in Older African American Adults

Abstract

Rumination has the potential to disrupt the diurnal cortisol rhythm with implications for physical and mental health. The Perseverative Cognition Hypothesis posits that the persistent cognitive representation of a stressor can prolong physiological stress response. Rumination, one form of perseverative cognition, can be assessed from two perspectives: the general tendency to ruminate and rumination in response to specific daily stressors. The present study examined the effect of both average and daily rumination on diurnal cortisol in older African American adults. Data were drawn from the Health among Older adults Living in Detroit (HOLD) study, an ongoing examination of healthy aging in African American adults, (N = 211; Mage = 67.6 yrs, SD = 8.5, range = 50–89). Across five days, participants completed daily diaries assessing rumination about the day’s most stressful event and provided four saliva samples per day from which cortisol data were obtained. Cortisol data was available for 203 individuals. Individuals with higher perceived stress and lower income ruminated more over the five days. Hierarchical linear models tested effects of average and daily rumination on diurnal cortisol. Average rumination did not predict diurnal cortisol slope. Furthermore, daily rumination did not predict diurnal slope across the current day or the subsequent day. Neither average nor daily rumination predicted diurnal cortisol in African American adults. The present study measured rumination across only five days; future studies are recommended to examine the effect of trait levels of rumination on cortisol dynamics in addition to daily rumination.