Strong friendships may literally slow aging at the cellular level

Long-Term Study Links Social Advantage to Youthful Biology

The findings were published in the October issue of Brain, Behavior and Immunity -- Health and draw on data from over 2,100 adults who participated in the long-running Midlife in the United States (MIDUS) study.

Anthony Ong, a psychology professor at Cornell University, and his colleagues discovered that people with greater "cumulative social advantage" -- a measure of lifelong social and emotional support -- tended to show slower biological aging and reduced chronic inflammation.

Measuring the Pace of Aging

The study examined two leading measures of biological age, called GrimAge and DunedinPACE. Both are epigenetic clocks that scientists use to predict health risks and life expectancy. Participants with richer and more consistent social relationships displayed younger biological profiles on both measures.

"Cumulative social advantage is really about the depth and breadth of your social connections over a lifetime," Ong said. "We looked at four key areas: the warmth and support you received from your parents growing up, how connected you feel to your community and neighborhood, your involvement in religious or faith-based communities, and the ongoing emotional support from friends and family."

The Biology of Connection

The researchers hypothesized that sustained social advantage becomes reflected in core regulatory systems linked to aging, including epigenetic, inflammatory and neuroendocrine pathways. Remarkably, they found that higher social advantage was linked to lower levels of interleukin-6, a pro-inflammatory molecule implicated in heart disease, diabetes and neurodegeneration. Interestingly, however, there were no significant associations with short-term stress markers like cortisol or catecholamines.

Why Lifelong Relationships Matter

Unlike many earlier studies that looked at social factors in isolation -- whether a person is married, for example, or how many friends they have -- this work conceptualized "cumulative social advantage" as a multidimensional construct. And by combining both early and later-life relational resources, the measure reflects the ways advantage clusters and compounds.

"What's striking is the cumulative effect -- these social resources build on each other over time," Ong said. "It's not just about having friends today; it's about how your social connections have grown and deepened throughout your life. That accumulation shapes your health trajectory in measurable ways."

Connection as a Form of Investment

This doesn't mean a single friendship or volunteer stint can turn back the biological clock. The authors suggest that the depth and consistency of social connection, built across decades and different spheres of life, matters profoundly. The study adds weight to the growing view that social life is not just a matter of happiness or stress relief but a core determinant of physiological health.

"Think of social connections like a retirement account," Ong said. "The earlier you start investing and the more consistently you contribute, the greater your returns. Our study shows those returns aren't just emotional; they're biological. People with richer, more sustained social connections literally age more slowly at the cellular level. Aging well means both staying healthy and staying connected -- they're inseparable."