Loneliness, social isolation, and biological aging: Evidence from two large population-based cohort studies

To examine the association between loneliness, social isolation, and biological aging in older adults.

We used data from the UK Biobank (N = 334,415) and NHANES III (N = 6364). Loneliness score and social isolation score were assessed using standardized scales at baseline. Three biomarker-based biological age (BA) measures were used: Klemera-Doubal method age (KdmAge), PhenoAge, and Homeostatic Dysregulation Age (HD Age).

In the UK Biobank study, higher levels of loneliness and social isolation were associated with increased risk of accelerated biological aging. Using KdmAge to define accelerated biological aging, participants with a loneliness score of 1 and 2 had adjusted odds ratios (ORs) of 1.03 (95% CI: 1.01-1.04) and 1.12 (95% CI: 1.08-1.15), respectively, compared to those with score of 0. Similarly, for social isolation, the ORs were 1.04 (95% CI: 1.02-1.05) for score of 1 and 1.13 (95% CI: 1.10-1.16) for score of 2. Consistent associations were also observed when accelerated biological aging was defined using PhenoAge and HD Age. Mediation analysis indicated that accelerated biological aging significantly mediated the link between social loneliness/isolation and all-cause mortality. Findings from the NHANES study supported these results.

Our study highlighted the significant impact of loneliness and social isolation on biological aging, suggesting that these social factors play a crucial role in the physiological decline in elderly people.