Associations of social support, depressive symptoms, and cognitive function among dementia-free older adults: A population-based study

INTRODUCTION: We sought to examine the cross-sectional associations of social support and depressive symptoms with cognitive function in dementia-free rural older adults. METHODS: This population-based cross-sectional study included 4719 participants (age ≥ 60 years) living in rural China. Social support and depressive symptoms were measured using the Social Support Rating Scale and the 15-item Geriatric Depression Scale, respectively. Global cognition, memory, verbal fluency, attention, and executive function were assessed using a neuropsychological test battery. Mild cognitive impairment (MCI) was defined following Petersen's criteria. Data were analyzed using general linear and logistic regression models. RESULTS: Greater social support was associated with lower likelihood of MCI and greater z-scores of global cognition, memory, verbal fluency, and executive function (all P < 0.05). Having depressive symptoms was associated with increased likelihood of MCI and lower z-scores of global cognition, memory, verbal fluency, attention, and executive function (all P < 0.05). Greater social support was associated with higher global cognitive z-score in men, higher memory z-score in APOE ε4 non-carriers, and higher executive function z-score in participants with school education (all P < 0.01). The association of depressive symptoms with lower z-scores of global cognition and attention was stronger among people with formal schooling than those without (P < 0.01). Furthermore, depressive symptoms could significantly mediate 46.97 % of the cross-sectional association between social support and global cognition. CONCLUSION: Late-life social support and having no depressive symptoms are associated with a reduced likelihood of MCI and better cognitive function in a rural Chinese older population, with the associations varying by sex, education, and APOE genotype.