Social isolation was associated with both second- and third-generation epigenetic aging clocks at 10-year follow-up, loneliness was associated only with third-generation clocks, and co-occurring social connection deficits were associated with the fastest epigenetic aging.
Key Findings
Results
Baseline social isolation was associated with accelerated epigenetic aging measured by both second- and third-generation DNA methylation clocks at 10-year follow-up.
Study used data from the Health and Retirement Study (n = 2343).
Doubly robust estimation analyses were used to assess associations.
GrimAge2 (a second-generation clock) showed an average treatment effect (ATE) of 0.79, 95% CI = [0.26, 1.33].
Associations were observed across multiple clock types, spanning both second- and third-generation clocks.
Results
Loneliness was associated with accelerated epigenetic aging only as measured by third-generation DNA methylation clocks, not second-generation clocks.
DunedinPACE (a third-generation clock) showed an ATE of 0.014, 95% CI = [0.001, 0.027] for loneliness.
Second-generation clocks did not show significant associations with loneliness.
This distinction suggests that loneliness and social isolation may operate through partially different biological pathways detectable at different levels of clock sensitivity.
Results
Relationship quality showed limited independent associations with accelerated epigenetic aging.
Both positive and negative relationship quality dimensions were examined.
Neither positive nor negative relationship quality showed strong independent associations with epigenetic aging clocks.
This finding contrasts with the significant associations observed for social isolation and loneliness.
Results
Co-occurring social connection deficits were associated with the fastest rates of epigenetic aging.
Individuals who were simultaneously socially isolated, lonely, and had low positive and high negative relationship quality showed the fastest epigenetic aging.
DunedinPACE for those with all deficits was 1.087, 95% CI = [1.066, 1.107], compared to 1.027, 95% CI = [1.019, 1.035] for those without these deficits.
This pattern suggests that multiple co-occurring social connection deficits have a compounding association with biological aging.
Results
Longitudinal accumulation of social isolation was most strongly associated with accelerated epigenetic aging, whereas earlier loneliness exposures appeared to have the strongest associations.
The study examined both the accumulation over time of social isolation and the timing of loneliness exposure.
Greater cumulative social isolation over time showed the strongest associations with epigenetic aging.
Earlier (rather than more recent) loneliness exposures appeared to have stronger associations with epigenetic aging.
These temporal patterns suggest that the biological embedding of social connection deficits may differ by dimension and timing of exposure.
Methods
The study examined four distinct dimensions of social connection in relation to epigenetic aging: social isolation, loneliness, positive relationship quality, and negative relationship quality.
Data were drawn from the Health and Retirement Study with a sample of n = 2343.
Epigenetic aging was assessed using both second-generation clocks (e.g., GrimAge2) and third-generation clocks (e.g., DunedinPACE).
A 10-year follow-up period was used to assess longitudinal associations.
Doubly robust estimation was employed to reduce confounding bias.
What This Means
This research suggests that different aspects of social connection — including feeling isolated, feeling lonely, and the quality of relationships — are linked to how quickly people age at a biological level, as measured by chemical changes in DNA known as epigenetic clocks. Using data from over 2,000 older adults followed for 10 years, the study found that social isolation (having few social contacts) was linked to faster biological aging across multiple types of epigenetic clocks, while loneliness (feeling alone even if socially connected) was only detectable with the most sensitive, newer clocks. Having poor relationship quality on its own did not show strong independent links to biological aging.
Importantly, people who experienced multiple social problems at once — being isolated, lonely, and having low-quality relationships — showed the fastest rates of biological aging compared to those without these problems. The study also found that how long someone has been socially isolated matters, with longer cumulative isolation being most harmful, while feeling lonely earlier in life appeared to have stronger effects than more recent loneliness.
This research suggests that social connection is not a single concept and that different dimensions of it may affect the body in different ways and at different points in time. Programs aimed at improving healthy aging may benefit from addressing multiple aspects of social connection simultaneously, rather than focusing on just one dimension such as loneliness or isolation alone.
Bu F, Fancourt D. (2026). Social Connection and Epigenetic Aging: Insights from DNA Methylation Clocks.. Annals of the New York Academy of Sciences. https://doi.org/10.1111/nyas.70402