Daily Social Interactions and HPA Axis Activity Among Midlife and Older Adults.

BACKGROUND AND OBJECTIVES: Older people experience fewer negative interactions and report less stress in response to interpersonal tensions. Less is known, however, about the implications of daily social interactions for biological stress responses. We evaluated links between daily positive and negative interactions and 2 key biomeasures of the hypothalamic-pituitary-adrenal axis: salivary cortisol and dehydroepiandrosterone sulfate (DHEA-S). We also considered the moderating effects of age. RESEARCH DESIGN AND METHODS: Participants included a random sample of 93 individuals aged 40-95 who completed 14 days of daily diary interviews and provided saliva samples during 4 of those days. RESULTS: Three-level piecewise models showed that individuals had higher sustained DHEA-S levels on days after reporting more positive interactions. Young-old adults (60-79) had lower overall DHEA-S on days when they had more negative interactions than oldest-old adults (80 and older). Oldest-old adults showed a flatter decline in DHEA-S on days after they reported more negative interactions compared to midlife adults (40-59). Daily social interactions were not significantly associated with cortisol. DISCUSSION AND IMPLICATIONS: Strategies to increase positive interactions may help to build physiological resilience to stress, particularly among midlife and young-old adults.