Evidence base
Perspectives on Psychological Science
Loneliness and Social Isolation as Risk Factors for Mortality: A Meta-Analytic Review
What it found
This meta-analysis found that social isolation, loneliness, and living alone were each associated with increased odds of early mortality (odds ratios of 1.29, 1.26, and 1.32 respectively). These effects held after adjusting for existing health status, and social deficits showed stronger predictive power in samples with an average age under 65.
Why it matters for practice
This is one of the foundational quantitative anchors for arguing that social connection is a health determinant in its own right, not a proxy for poor health. The age finding is worth flagging to readers who assume loneliness interventions are primarily an older-adult concern: the evidence here points the other way.