Abstract
BACKGROUND: This study aims to systematically review the association between social relationships and cognitive impairment in the elderly, and to identify risk and protective factors through quantitative meta-analysis, providing evidence to inform cognitive health intervention strategies. METHODS: PubMed, Embase, Web of Science, CNKI, and other databases were systematically searched for studies published before November 1, 2024. Eligible studies included cross-sectional and cohort studies involving adults aged ≥60 years. Separate meta-analyses were conducted for ratio-based effect sizes (OR/HR/RR) and regression coefficients (β) to synthesize the associations between social relationships and cognitive impairment. RESULTS: From 1013 retrieved records, 11 studies were included. Meta-analysis showed that reduced social networks and social isolation were significantly associated with an increased risk of cognitive impairment (e.g., loneliness and mild cognitive impairment: OR = 2.89, 95% CI = 1.19-7.02). In contrast, larger social networks and frequent social participation were associated with a substantially lower risk of cognitive impairment, with participation in ≥1 social activity linked to an approximately 64% risk reduction. β-based meta-analysis further indicated positive associations between social support and cognitive performance, while specific activities such as volunteering conferred additional protective effects. Moderate heterogeneity was observed across social relationship dimensions. CONCLUSION: Social relationships play an important role in maintaining cognitive health in older adults. This meta-analysis provides quantitative evidence supporting both the risk and protective effects of social relationships on cognitive impairment, underscoring the importance of promoting social engagement to support cognitive health in aging populations.