Depression as a risk factor for Alzheimer disease - The MIRAGE study

Background: Depression symptoms may be associated with the development of Alzheimer disease (AD). Objectives: To evaluate the association between depression symptoms and risk of AD, and to explore the temporal aspects of this association.. Setting: Academic institutions with specialized memory clinics. Design: Cross-sectional, family-based, case-control study with standardized self- and proxy questionnaires to collect information on depression symptoms and other risk factors. Participants: A total of 1953, subjects with AD and 2093 of their unaffected relatives enrolled in the Multi-institutional Research in Alzheimer's Genetic Epidemiology Study. Main Outcome Measures: Odds ratios (ORs) of AD were estimated with and Without depression symptoms, adjusted for age, sex, education, history of head trauma, and apolipoprotein E status. Results: There was a significant association between depression symptoms and AD (adjusted OR, 2.13; 95% confidence interval [CI], 1.71-2.67). In families where depression symptoms first occurred within I year before the onset of AD, the association was higher (OR, 4.57; 95% Cl, 2.87-7.31), while in the families where the depression symptoms first occurred more than 1 year before the onset of AD, the association was lower (OR, 1.38; 95% Cl, 1.03-1.85). In families where depression symptoms first occurred more than 25 years before the onset of AD, there was still a modest association (OR, 1.71; 95% Cl, 1.03-2.82). Conclusions: Depression symptoms before the, onset of AD are associated with the development of AD, even-in families where first depression symptoms occurred more than 25 years before the onset of AD. These data suggest that depression symptoms are a risk factor for later development of AD.