Background: Chronic interpersonal stress has been linked to accelerated biological aging, but questions remain about which relationship stress domains may be most consequential during midlife.
Research design and methods: Linear regression models quantified the cross-sectional associations between domain-specific relationship stressors (marital risk, partner strain, family strain, friendship strain) and next-generation epigenetic clocks (DunedinPACE and GrimAge2) in 1,310 midlife adults from the Midlife in the United States study (mean age = 51, SD = 13).
Results: Controlling for sociodemographic and health behaviors, we found that friendship strain was uniquely associated with accelerated aging (GrimAge2: 0.03 SD increase, 95% CI: 0.01, 0.05, p = 0.003; DunedinPACE: 0.05 SD increase, 95% CI: 0.01, 0.09, p = 0.030). No statistically significant associations were observed for the other stressors with GrimAge2 or DunedinPACE in fully adjusted models.
Conclusions: These findings identify friendship strain as a potential specific risk factor for accelerated biological aging in midlife. Future research should investigate behavioral and physiological mechanisms linking friendship quality to cellular aging.
Keywords: Biological embedding; epigenetic epidemiology; interpersonal strain; psychobiological processes; stress physiology.
Stress from close relationships can harm health, but it is less clear how different types of relationship stress, such as from family, romantic partners, or friends, affect how the body ages. In this study, we analyzed data from a national sample of midlife adults in the United States to explore the links between relationship stress and the body’s aging process. Biological aging was assessed using “epigenetic clocks,” blood-based biomarkers that reflect age-related changes at the cellular level. We found that stress from friendships, but not family or romantic relationships, was linked to faster biological aging. These findings suggest that peer relationships may have a unique influence on long-term health. Reducing stress from friendships could be a promising direction for supporting healthy aging.