Psychosocial factors in the association between somatic discomfort and suicidality across adulthood: A population-based mediation analysis.

Background

Somatic discomfort is associated with suicidality, but age-specific psychosocial correlates are unclear. We examined statistical indirect associations through loneliness, social isolation, and depressive disorder across adulthood.

Methods

We analyzed 5511 adults aged 18-79 years from the 2021 National Mental Health Survey of Korea, stratified into 18-39, 40-59, and 60-79 years. Somatic discomfort was assessed using the EQ-5D pain/discomfort item; loneliness and social isolation were single-item indicators; and depressive disorder and suicidality were assessed with the K-CIDI 2.1. Probability-scale indirect effects were estimated using Firth/FLIC models with 1000 bootstrap replicates. Models adjusted for sex, education, income, current marital status, and relevant psychiatric covariates; physical activity was examined in sensitivity analyses.

Results

No significant indirect associations were observed at ages 18-39. At ages 40-59, depressive disorder showed a significant indirect association (ACME = 0.00911, 95% CI 0.00151-0.02028). At ages 60-79, somatic discomfort was associated with suicidality (OR = 4.01, 95% CI 1.48-10.86), with significant indirect associations through loneliness (ACME = 0.00323), social isolation (ACME = 0.00295), and depressive disorder (ACME = 0.01101). Loneliness and social-isolation effects did not differ (p = 0.882). After physical-activity adjustment, middle-aged depression and older-adult social isolation and depression remained significant, whereas older-adult loneliness did not.

Conclusions

Depressive disorder showed the most consistent statistical indirect association, with loneliness and social isolation additionally evident in later life. These cross-sectional findings support age-sensitive assessment but do not establish temporal or causal mediation.