Associations of depressive symptoms and lifestyles with cognitive function: results from two cross-sectional studies among middle-age and older Chinese populations

BACKGROUND: Depression and cognitive decline are both major health problems worldwide. This study aims to investigate the effects of depressive symptoms and its joint function with lifestyles on cognitive function among the Chinese populations. METHODS: This research included two cross-sectional studies from Hubei (n = 7756) and Shanghai (n = 4751), China. The depressive symptoms were surveyed by the 15-item Geriatric Depression Scale (GDS-15), and cognitive function was assessed by the Mini-mental State Examination (MMSE). RESULTS: We observed significant association between depression and decreased MMSE score [β (95%CI) = -0.70 (-0.97, -0.42) and -3.15 (-3.59, -2.70) in Hubei and Shanghai, respectively] and elevated risk of MCI [OR (95%CI) = 1.59 (1.20, 2.08) and 2.75 (2.06, 3.66), respectively] in both populations. Additionally, individuals who reported physically active, kept an optimal sleep duration, and higher healthy lifestyle score (HLS) exhibited a better cognition in both populations. More importantly, the adverse associations between depressive symptoms and cognition were diminished among subjects adopting five types of healthy lifestyles (HLS = 5) [Hubei: β (95%CI) = -0.20 (-0.82, 0.41) and OR (95%CI) =0.82 (0.24, 2.12), P-int = 0.047 and 0.046; Shanghai: β (95%CI) = -0.80 (-1.70, 0.10) and OR (95%CI) =1.85 (0.53, 5.06), P-int < 0.001 and 0.151]. Furthermore, we observed joint effects of non-depressed status with healthy lifestyles on cognition. CONCLUSION: Depressive symptoms are associated with impaired cognitive function and this association could be attenuated by healthy lifestyles.