Objectives: To investigate factors associated with depressive disorders and mortality among very old adults (85+) with and without dementia.
Methods: This population-based cohort study with repeated cross-sectional recruitment and prospective mortality follow-up utilized data from the Umeå 85+/GERDA (GErontological Regional DAtabase) home visit interviews with data collected between 2000-2017. The sample consisted of 2485 participants. Of these participants, 969 (39.0%) had dementia, and 466 (48.1%) had dementia and a depressive disorder. Of the 1516 (61.0%) participants without dementia, 387 (25.5%) of them had a depressive disorder. Logistic and cox regression models were utilized to explore the data.
Results: Of participants with dementia and a depression evaluation (n=746), 357 (47.9%) had died within two years from inclusion, and of those with dementia and a depressive disorder 175 (48.5%) had died. Of participants without dementia (n=1266), 216(17.1%) had died within two years, and of those without dementia and with a depressive disorder 73 (22.9%) had died. Depressive disorders were a statistically significant predictor of mortality among participants without dementia (p=.021). Different factors were associated with depression in participants with and without dementia.
Discussion: Dementia disorders were associated with increased two-year mortality, but depressive disorders showed no statistically significant independent association with mortality after adjustment. Among participants without dementia, depressive disorders were independently associated with an increased mortality risk. Measures to better identify and treat depressive disorders among very old adults should urgently be implemented. Further research into the association between depressive disorders and different dementia disorders, as well sex differences, is warranted.