The present study indicates that higher engagement in social contact or activities, along with a positive perception of neighborhood, is significantly linked to lower depressive symptoms (gloom and PHQ score ≥ 10) among older adults in Korea. Social contact with friends, relatives, and neighbors was significantly associated with lower depressive symptoms across the high- and low-income groups. Despite the cross-sectional nature of the analysis, the results suggest the importance of social relationships in preventing depression in the aging populations of Korea, where familial bonds have strong cultural significance.
Our findings align with those of previous studies, emphasizing the consistent link between social contact with close acquaintances and lower depressive symptoms [16, 17, 22, 23]. Acknowledging that the types of social networks and their protective effects on mental health may vary according to the cultural context [24], recent comparative studies have revealed that social isolation is more widespread and on the rise among older adults in Japan than in England [16, 17, 22]. This trend is attributed, at least in part, to diminished contact with children and relatives. Other studies have shown that financial or instrumental support for older adults is provided through social networks, primarily derived from close relationships with family and friends [23, 25]. Given the ongoing increase in the number of small families and single-person households in South Korea, these findings prompt a deeper exploration of tailored social interventions to support the mental health of older adults.
In terms of demographic variables, a higher household income was significantly associated with fewer depressive symptoms (PHQ-9 score < 10) in the multivariate analysis. The observed association between income level and depressive symptoms is consistent with the findings of previous studies [26–31]. It is notable that the effect size of income in the highest income group (≥ 3 million KRW) in Model 2 (aOR: 0.443, compared with the lowest income group) slightly diminished when accounting for social relationship variables in Model 3 (aOR: 0.488). Furthermore, the present findings show a consistent link between social contact and lower depressive symptoms across both high- and low-income groups. This aligns with previous results, suggesting that the strong link between low income and severe depressive symptoms can be alleviated by high levels of social support [32]. In this context, financial interventions as well as interventions specifically targeting the promotion of social relationships may prove to be efficacious in mitigating the risk of depression. These findings have significant policy implications, particularly in regions where social security measures for older adults remain insufficient.
The role of working is independently linked with lower depressive symptoms, perhaps because of the sense of self-efficacy and opportunities for social relationship that work provides. Working extends beyond financial considerations and plays a pivotal role in shaping personal identity and offering advantages, such as economic resources, social integration, and personal control [33]. Several studies have found an advantage in work to relieve depression or improve mental health, even after controlling for physical health for older adults [33–35]. However, it is crucial to note that the meaning of work and its impact on the mental health of older adults may vary depending on social group and personal circumstances [36]. Continuing to working beyond retirement age may indicate financial hardship, which is known to be associated with poor mental health [37]. Previous findings from a community survey of older Koreans have demonstrated an association between physical labor and higher depressive symptoms [38]. These findings suggest that various contextual factors, such as socioeconomic status, job characteristics, and work environment may influence the relationship between work and depression in different directions. Given the high poverty rate among older Koreans [39] the relationship between work and lower depression in this study warrants further research that considers more detailed factors.
Among the personal health behavior factors, engaging in alcohol consumption at least once per month was associated with fewer depressive symptoms, as were nonsmoking and regular physical activity. However, this interpretation is limited because the current study did not account for high-risk drinking. Previous reports, including prospective designs, have suggested that the incidence of depression is higher among long-term alcohol abstainers and heavy drinkers than among moderate drinkers in older adults [40–42]. A longitudinal study with data from 19 countries collected between 2004 and 2014 found that moderate alcohol consumption (drinking ≥ 1 days a week, with drinks ≤ 3 for men or ≤ 2 for women per day), compared with long-term abstinence, occasional drinking, and heavy drinking, was associated with a lower risk of depression among individuals aged 50 years or older [42]. The association between moderate drinking and lower depression in older adults may be related to drinking-related behaviors such as social activities that commonly accompany drinking [43]. Further investigation is necessary to determine the drinking-related behaviors associated with reduced depression; however, caution is warranted in approaches to alcohol use and mental health. A substantial body of research has consistently demonstrated that at-risk drinking is closely associated with depression [44, 45]. The notion that there is no safe or recommended minimum level of alcohol consumption is supported by a growing body of evidence, including large-scale observational studies [40, 42].
This study had several limitations that should be considered when interpreting the results. First, the data lacked variables related to the target population’s cognitive function, which may influence depressive symptoms. However, given that the survey was conducted through face-to-face visits by surveyors in respondents’ homes, it is likely that participants with severe cognitive decline were excluded from the study. Second, this study did not employ a time-series analysis, which imposes constraints on the interpretation of the findings. As the results of the PHQ-9 questionnaire will be accumulated in South Korea, which is transitioning into a super-aged society, changes in social networks and mental health in older adults can be tracked. Third, the analysis was based on self-reported data, which implies the possibility of self-report bias. This may contribute to the contradictory results observed across age groups for questions about gloom and the PHQ-9. Indeed, some studies have identified older age as a risk factor for depression, whereas others have reported otherwise [46]. Considering that late-life depression has been neglected and underdiagnosed [47], the results might have differed if depression symptoms had been assessed using clinical evaluations rather than screening tools. Finally, residual confounding may exist due to potential confounders that could not be included in the analysis or adjusted for, such as stressful life events or a family history of mental disorders.