Depressive symptoms predict incident dementia during short- but not long-term follow-up period

BACKGROUND Whether depression is a long-term risk factor for dementia or represents a dementia prodrome is unclear. Therefore, we examined the relationship between depressive symptoms and dementia during short and long follow-up in a population-based cohort. METHODS In the Rotterdam Study, 4393 nondemented individuals were followed for incident dementia for 13.7 years by continuous monitoring. Cox proportional hazards models for different time intervals were used to estimate the risk of incident dementia. RESULTS Five-hundred eighty-two participants developed dementia during 13.7 years. Persons with depressive symptoms had an 8% increased risk of dementia compared with those without depressive symptoms during the overall follow-up. The risk was highest in the short and intermediate follow-up, particularly in men. We did not find an association in the follow-up period beyond 10 years. CONCLUSION Our results suggest that late-life depressive symptoms are part of a dementia prodrome rather than an independent risk factor of dementia.