Clinically significant anxiety as a risk factor for Alzheimer's disease: Results from a 10-year follow-up community study.

Objective: There is growing evidence for an association between anxiety and an increased risk of dementia, but it is not clear whether anxiety is a risk factor or a prodromic symptom. In this study, we investigated if clinically significant anxiety increases the risk of developing Alzheimer's disease (AD) up to 10 years later.

Methods: We used data from the longitudinal Zaragoza Dementia and Depression (ZARADEMP) Project. Excluding subjects with dementia at baseline left us with 3044 individuals aged >65 years. The Geriatric Mental State-Automated Geriatric Examination for Computer Assisted Taxonomy (GMS-AGECAT) package was used to identify cases and subcases of anxiety. AD was diagnosed by a panel of research psychiatrists according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria. Multivariate survival analysis with a competing risk regression model was performed.

Results: We observed a significant association between clinically significant anxiety at baseline and AD risk within a 10-year follow-up (SHR 2.82 [95% CI 1.21-6.58]), after controlling for confounders including depression. In contrast, isolated symptoms of anxiety were not significantly associated with an increased incidence of AD.

Conclusion: Our results support the hypothesis that clinically significant anxiety is an independent risk factor for AD and not just a prodromic symptom. Future studies should clarify if treating anxiety reduces the incidence of AD.