Association between individual social capital and depressed mood in older adults in Iran: results from baseline data of Birjand Longitudinal Aging Study

BMJ Open. 2025 Aug 5;15(8):e096145. doi: 10.1136/bmjopen-2024-096145.

ABSTRACT

OBJECTIVES: To examine the association between individual social capital and depression in older adults in Iran and to test the hypothesis that higher levels of social capital are inversely associated with depressive symptoms.

DESIGN: Cross-sectional study using baseline data from a longitudinal cohort.

SETTING: Community-based study conducted in primary care settings across urban and rural areas of Birjand County, Eastern Iran.

PARTICIPANTS: A total of 1348 community-dwelling individuals aged 60 years and older were recruited through multistage stratified cluster random sampling. Participants who were bedridden or had end-stage disease (life expectancy<6 months) were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was depression status, measured using the Patient Health Questionnaire 9 items, with a score≥10 indicating depression. The main explanatory variable was social capital, assessed using a validated 69-item questionnaire capturing domains such as collective activity, social trust and network structure. Univariable and multivariable logistic regression analyses were conducted to estimate adjusted ORs and 95% CIs for associations between depression and social capital dimensions. Statistical analyses were performed using Stata V.12.0 RESULTS: Of the total participants, 268 (19.94%) were identified as having depressive symptoms, with a significantly higher prevalence among women (27.44%) compared with men (11.88%). Depression was more prevalent among those in the lowest wealth quintile (32.09%) and individuals with low literacy levels (28.10%). Participation in collective activities was inversely associated with depression in the second (OR=0.62, 95% CI (0.42 to 0.93)), third (OR=0.45, 95% CI (0.29 to 0.71)), fourth (OR=0.59, 95% CI (0.37 to 0.93)) and fifth (OR=0.37, 95% CI (0.22 to 0.61)) quintiles. Social trust was also associated with lower odds of depression in the third (OR=0.62, 95% CI (0.39 to 0.99)) and fourth (OR=0.64, 95% CI (0.42 to 0.97)) quintiles. Furthermore, the second (OR=0.63, 95% CI (0.40 to 0.99)) and fifth (OR=0.38, 95% CI (0.23 to 0.63)) quintiles of social network structure were inversely related to depression. These findings suggest that higher levels of social capital, particularly in terms of collective participation, trust and social networks, are associated with a reduced likelihood of depressive symptoms in older adults.

CONCLUSIONS: Higher levels of social capital, particularly collective engagement, interpersonal trust and diverse social networks, are associated with lower odds of depression in older adults. These findings support the need for community-based interventions to strengthen social capital as a strategy for mental health promotion among the elderly in low-income and middle-income settings.

PMID:40764074 | DOI:10.1136/bmjopen-2024-096145