ABSTRACTS FROM MEDICAL LITERATURE FOR THE GERIATRICS PRACTITIONER

DEPRESSION AND RISK FOR AD
A history of depression may increase risk for developing Alzheimer’s disease (AD) later in life. Clarifying this relation might improve understanding of risk factors for and disease mechanisms in AD. The authors’ objective was to systematically review and complete a meta-analysis on the relationship of depression and AD. They conducted electronic bibliographic searches of MEDLINE, PsychLit, EMBASE, and BIOSIS, using search terms sensitive to studies of etiology combined with searches on terms related to depression and AD, and reviewed reference lists of articles. Studies with data contrasting depressed vs nondepressed patients who did and did not later develop AD were included. Studies that related continuous measures of depression and cognitive status were excluded. Numerical data were independently extracted by three reviewers. Investigators also rated studies on a scale that assessed quality indicators for observational studies. Data on the interval between observation of depression and the diagnosis of AD were collected when available. Meta-analytic evaluation with random-effects models resulted in pooled odds ratios of 2.03 (95% confidence interval, 1.73-2.38) for case-control and of 1.90 (95% confidence interval, 1.55-2.33) for cohort studies. Findings of increased risk were robust to sensitivity analyses. Interval between diagnoses of depression and AD was positively related to increased risk of developing AD, suggesting that rather than a prodrome, depression may be a risk factor for AD. The authors concluded that a history of depression may confer an increased risk for later development of AD. This relation may reflect an independent risk factor for the disease.

Ownby RL, Crocco E, Acevedo A, et al. Depression and risk for Alzheimer disease: Systematic review, meta-analysis, and metaregression analysis. Arch Gen Psychiatry 2006;63:530-538.