Age and sex-specific associations between depressive symptoms, body mass index and cognitive functioning among Korean middle-aged and older adults: a cross-sectional analysis

BACKGROUND: Although depression and body weight have been noted as important predictors of cognitive health, it remains unclear how age and sex influence the mechanism by which depressive symptoms and body weight are associated with cognitive functioning. This study examined whether and how the relationships between depressive symptoms and cognitive functioning mediated by body mass index (BMI) differ in terms of age and sex. METHODS: A cross-sectional analysis of a large sample of population-based data (N = 5,619; mean age 70.73 [± 9.07]), derived from the Korean Longitudinal Study of Aging, was conducted with hierarchical mediated-moderation regressions and a PROCESS macro approach in SPSS. Depressive symptoms were measured through the 10-item Center for Epidemiologic Studies Depression (CES-D) scale, and cognitive functioning was assessed with the Korean Mini-Mental State Examination (K-MMSE). RESULTS: The results showed that depressive symptoms were significantly associated with cognitive decline directly and indirectly through reduced BMI. The estimated coefficients indicated that a one standard deviation increase in CES-D scale was associated with about 0.9 decrease in K-MMSE score. However, the indirect relationship between depressive symptoms and cognitive function through BMI emerged only in men or individuals older than 70 years. CONCLUSIONS: The findings suggest that a careful assessment of BMI is warranted for early detection and prevention of cognitive decline related to depressive symptoms, particularly among older men.