Depressive symptoms and risk of Alzheimer's disease in more highly educated older people

Abstract

Background and objective: In an earlier study we observed that a depressive syndrome was highly predictive of developing Alzheimer's disease (AD) in older persons with normal baseline cognition and higher levels of education. We interpreted these findings as the depression being an early noncognitive manifestation of AD in persons with more cognitive reserve. The present study examines whether specific symptoms of depression can be identified that predict AD among older subjects with higher levels of education.

Design and participants: In the community-based Amsterdam Study of the Elderly (AMSTEL), a sample of 3,147 nondemented persons with normal cognition, 65 to 84 years old, was selected and divided into subjects with >8 years and < or =8 years of education. At baseline, the presence or absence of 12 specific symptoms of depression was assessed. At follow-up, patients with incident AD were diagnosed according to DSM-IV criteria in a two-step diagnostic procedure.

Results: After an average follow-up of 3.2 years, 1,911 persons were reevaluated, of whom 22 with > 8 years and 31 with < or =8 years of education had developed AD. Multivariate logistic regression analyses showed that among persons with >8 years of education depressed mood and subjective bradyphrenia were strongly associated with incident AD. No association between depressive symptoms and AD was observed among subjects with < or =8 years of education.

Conclusions: Both depressed mood and subjective bradyphrenia seem to indicate subclinical AD in older people with higher levels of education. Clinicians should be alert that in these persons, AD may become apparent within a relatively short period of time.