Social interactions and physical symptoms in daily life: quality matters for older adults, quantity matters for younger adults.

The present study examined how the different attributes of daily social interactions (quality and quantity) were associated with physical health, and how these associations vary with age. Using an ecological momentary assessment approach, participants from an adulthood lifespan sample ( = 172; aged 20-79 years) reported their social interactions five times daily, and physical symptoms and symptom severity at the end of each day, for one week. Number of physical symptoms and physical symptom severity. There was a within-person main effect of the quality (positivity), but not the quantity (frequency), of social interactions on the number of reported physical symptoms and their severity. Moderation analyses further revealed that the quality of daily social interactions predicted fewer physical symptoms for older adults, but not for younger adults; in contrast, the frequency of social interactions predicted less severe physical symptoms for younger adults, but not for older adults. Finally, the reported severity of physical symptoms predicted less frequent but more positive social interactions the next day. Our findings point to the bidirectional associations between social interactions and health and highlight the importance of considering individuals' developmental context in future research and interventions.