Cognitive function predicts all-cause mortality independent of social engagement among community-dwelling elderly Japanese men: a 15-year prospective cohort study.

BACKGROUND

As the global population ages, cognitive impairment has become a growing public health concern. Although epidemiological studies have examined its association with mortality, sex-stratified analyses and community-based investigations in elderly Asian men remain scarce. Furthermore, social engagement may confound the association between cognitive impairment and mortality; yet few studies among community-dwelling elderly Asian men have simultaneously examined cognitive impairment and social engagement in relation to all-cause mortality in a prospective cohort design. This study therefore aimed to examine whether cognitive impairment is associated with an increased risk of all-cause mortality independent of social engagement among community-dwelling elderly Japanese men over a 15-year follow-up period.

METHODS

This prospective cohort study enrolled 2,174 men aged ≥65 years. Follow-up assessments were conducted at five, ten, and fifteen years, with all-cause mortality as the primary outcome. Cognitive function was assessed using the Mini-Mental State Examination. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models to examine the association between cognitive function and all-cause mortality. Confounder-adjusted Kaplan-Meier survival curves were generated using inverse probability of treatment weighting.

RESULTS

The final analytic sample comprised 1,741 men. High social engagement was associated with a lower risk of all-cause mortality. Compared with participants with normal cognitive function, the hazard ratios (HRs) for all-cause mortality were 1.29 (95% CI: 1.06-1.56) for mild cognitive impairment and 1.59 (95% CI: 1.10-2.29) for severe cognitive impairment, after adjusting for potential confounding factors including social engagement.

CONCLUSIONS

Cognitive impairment independently predicts an increased risk of all-cause mortality in community-dwelling elderly Japanese men.