Depression and the Risk of Dementia and All-Cause Mortality Among Japanese Older Adults: A 9-Year Longitudinal Study From JAGES

Abstract

Abstract Background This study aims to investigate the association and dose–response relationship between depression, dementia, and all-cause mortality based on a national cohort study of older adults in Japan. Methods We conducted a longitudinal study of 44,546 participants ≥65 years from 2010–2019 Japanese Gerontological Evaluation Study. The Geriatric Depression Scale-15 was used to assess depressive symptoms and the long-term care insurance was used to assess dementia. Fine–Gray models and Cox proportional hazard models were used to explore the effect of depression severity on the incidence of dementia and all-cause mortality, respectively. Causal mediation analysis were used to explore the extent of association between dementia-mediated depression and all-cause mortality. Results We found that both minor and major depressive symptoms were associated with the increased cumulative incidence of dementia and all-cause mortality, especially major depressive symptoms (p < .001). The multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for dementia were 1.25 (1.19–1.32) for minor depressive symptoms and 1.42 (1.30–1.54) for major depressive symptoms in comparison to non-depression; p for trend < .001. The multivariable-adjusted HRs and 95% CIs for all-cause mortality were 1.27 (1.21–1.33) for minor depressive symptoms and 1.51 (1.41–1.62) for major depressive symptoms in comparison to non-depression; p for trend < .001. Depression has a stronger impact on dementia and all-cause mortality among the younger group. In addition, dementia significantly mediated the association between depression and all-cause mortality. Discussion Interventions targeting major depression may be an effective strategy for preventing dementia and premature death.