Earlier-Life Depression and Dementia Risk Twenty Years Later: A Population-Based Register Study in Finland

Kaarina Korhonen
Elina Einio, University of Helsinki
Taina Leinonen, Finnish Institute of Occupational Health
Lasse Tarkiainen, University of Helsinki
Pekka Martikainen, University of Helsinki

Previous studies have provided conflicting evidence on whether depression is a risk factor for or a prodromal symptom of dementia. To avoid confounding by a shared neuropathological cause, this study measured depression already 20–29 years before the follow-up for dementia. We estimated hazard ratios for incident dementia at the age of 65+ in a population-based sample of Finnish residents (n=146,709) in 2000–2012. Depression 20–29 years before baseline and dementia during the follow-up were identified from linked hospital registers. A history of depression was related to a 1.43-fold hazard (95% CI 1.21–1.68) of developing dementia. This excess hazard was only modestly related to earlier-life health conditions and was not moderated by cognitive reserve indicated by education. Adjustment for later-life health conditions attenuated the excess hazard by 20–35%. The results provide evidence for that depression is a risk factor for dementia and suggest that later-life health conditions make important targets for intervention.

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 Presented in Session 6. Health & Mortality & Aging