Incidence of depressive symptoms and their associations with lifestyle and social support networks among community-dwelling older adults: a sex-stratified longitudinal study using the JAGES study.

BACKGROUND: Primary prevention of depressive symptoms among independent older adults is a critical public health challenge. Lifestyle factors and social support networks are increasingly recognized as pivotal determinants of mental health in this population. However, few longitudinal studies have examined these relationships, and little attention has been directed to gender-based differences. We investigated the associations between lifestyle factors and social support networks and the depressive symptoms of community-dwelling independent older adults in a sex-stratified 3-year longitudinal study. METHODS: This study used data from the Japan Gerontological Evaluation Study. Participants were functionally independent individuals aged 65 years and older. Our final analysis included data for 6,929 individuals collected between 2019 and 2022. A logistic regression analysis was conducted with depressive symptoms in 2022 as the dependent variable. Lifestyle factors and social support networks were treated as independent variables, with age, chronic diseases, and household income included as covariates. The effects of interactions between lifestyle factors and social support networks on depressive symptoms were also analyzed. RESULTS: The prevalence of depressive symptoms was 10.7% in men and 11.6% in women in the 3-year follow-up. The incidence rate of newly developed depressive symptoms (per 1,000 person-years) was 35.6 for men and 38.8 for women. Sex-based differences were found in lifestyle and social support network factors associated with depressive symptoms. In men, walking for more than 30 min per day, insomnia, and emotional support were significantly associated with the risk for depressive symptoms. In women, walking for more than 30 min per day, insomnia, and instrumental support were significantly associated with the risk for depressive symptoms. No interaction effects between lifestyle factors and social support networks on depressive symptoms were observed in either men or women. CONCLUSION: These findings underscore the importance of preventing depressive symptoms among older adults, particularly through the lens of gender-specific differences in lifestyle factors and social support networks associated with depressive symptoms. This study highlights the potential for developing targeted and effective primary prevention strategies by identifying modifiable determinants of depressive symptoms.