Objectives: The vascular depression hypothesis posits that cerebrovascular burden contributes to the development of depression symptoms in late life. Building on work that suggests that vascular depression is a prodrome for frailty, this paper tests a theoretical framework that vascular depression symptoms are an early marker of a broader pattern of decline characterized by more frailty symptoms and shortened lifespan, and that vascular depression symptoms predict mortality through frailty.
Methods: The sample was drawn from the Health and Retirement Study and included 1361 stroke-free women over the age of 80. Data were included from six biannual waves from 1998 to 2008 (waves 4-9). A vascular depression symptomatology variable was based on Center for Epidemiological Studies Depression Scale (CES-D) scores and number of cerebrovascular risk factors (hypertension, diabetes, cardiac disease, and smoking). Frailty was measured based on wasting, slowness, weakness, fatigue, and falls. Vascular depression and frailty symptoms were modeled using slope and intercept terms. Mortality was modeled using a discrete-time survival term.
Results: The data supported the proposed model (RMSEA = 0.051; CFI = 0.971; X² = 234.84, p < 0.001). Higher vascular depression symptom slope and intercept scores significantly predicted higher frailty slope and intercept scores, respectively. Frailty intercept scores significantly predicted mortality. The vascular depression symptoms indirectly predicted mortality through frailty symptoms. A second model testing the competing hypothesis - that frailty symptoms lead to vascular depression symptoms and indirectly to mortality - was not supported by the data.
Conclusions: Results suggest that vascular depression symptoms are associated with a clinical trajectory that includes greater frailty and shortened remaining lifespan.