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

Mar 27, 2026Journal of affective disorders

How Loneliness and Social Isolation Are Linked to Biological Aging in Large Population Studies

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Longevity & Aging on OpenScience ↗PubMed ↗DOI ↗

Abstract

Participants with a loneliness score of 2 had an adjusted odds ratio of 1.12 for accelerated biological aging compared to those with a score of 0.

Higher levels of loneliness and social isolation are associated with increased risk of accelerated biological aging in older adults.
Adjusted odds ratios for accelerated biological aging were 1.03 and 1.12 for loneliness scores of 1 and 2, respectively.
For social isolation, the adjusted odds ratios were 1.04 for a score of 1 and 1.13 for a score of 2.
Similar associations were observed with different measures of biological age, including PhenoAge and Homeostatic Dysregulation Age.
Accelerated biological aging significantly mediated the connection between social loneliness/isolation and all-cause mortality.
Findings from the NHANES study supported the associations observed in the UK Biobank study.

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

METHODS: 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).

RESULTS: 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.

CONCLUSIONS: 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.