Risk factors for geriatric depression: the importance of executive functioning within the vascular depression hypothesis

BACKGROUND: Results from recent studies addressing the vascular depression hypothesis have been mixed, with cerebrovascular risk factors (CVRFs) predicting depression in some geriatric patients but not in others. The current study seeks to examine executive dysfunction as a potential moderator of the relationship between CVRFs and depressive symptoms. METHODS: Data concerning CVRFs, executive functioning, and depressive symptoms from 77 geriatric rehabilitation patients were incorporated to test the hypothesis that patients with executive dysfunction and greater CVRFs would demonstrate the highest levels of depression over time. CVRFs (diabetes, hypertension, atrial fibrillation) were measured via diagnosis by treating physician. Depression was assessed using the 15-item Geriatric Depression Scale (GDS) at baseline and at 6-month and 18-month follow-ups. Executive functioning was measured at baseline using the Initiation/Perseveration (IP) Subtest of the Mattis Dementia Rating Scale. RESULTS: Multivariate analysis of variance demonstrated a significant statistical interaction between the number of CVRFs and scores on the IP Subtest on depressive symptoms. Patients with two or more CVRFs and lower IP scores demonstrated significantly greater depressive symptoms at baseline and at 18-month follow-up than patients with fewer CVRFs and higher IP scores. The univariate effect at 6 months was not significant. CONCLUSION: The current data suggest that scores on an index of executive functioning may moderate the relationship between CVRFs and depressive symptoms. Interpretation of these findings is provided in the context of the vascular depression hypothesis and related frontostriatal dysfunction. Patients with greater CVRF burden and poor executive functioning may be at particularly high risk for depression.