Do depressive symptoms predict Alzheimer's disease and dementia?

Background. Depressive symptoms are common in seniors and may predict dementia. The objective of this study was to evaluate multiple measures of depressive symptoms to determine whether they predict subsequent Alzheimer's disease (AD) or dementia. Methods. This population-based cohort study with 5-year follow-up included 766 community-dwelling seniors (ages 65+ years) in Manitoba, Canada. Measurements considered were the Center for Epidemiologic Studies Depression (CES-D) scale, participant-reported medical history, and duration of depression. Results. Total CES-D score was a significant predictor of AD and dementia when categorized as a dichotomous variable according to the cutoff scores of 16 and 17, a CES-D cutoff of 21 was a significant predictor of AD and a marginally significant predictor of dementia. When analyzed as a continuous variable, CES-D score was marginally predictive of AD and dementia. Neither participant-reported history of depression nor participant-reported duration of depression was significant in predicting AD or dementia. Conclusion. Because depressive symptoms as measured by the CES-D predict the development of AD and dementia over 5 years, clinicians should monitor their older patients with these symptoms for signs of cognitive impairment.