The vascular depression hypothesis: the influence of age on the relationship between cerebrovascular risk factors and depressive symptoms in community dwelling elders.

The current study examined the moderating effect of age on the relationship between cerebrovascular risk factors (CVRF's) and depressive symptoms. Consistent with the broader vascular depression model, it was hypothesized that CVRF's would demonstrate a stronger link to depressive symptoms in the older age groups than among the younger age groups. Data from 2916 adults from the Resources, Stress, and Older Persons Panel Study were utilized. Path analysis was used to estimate direct and indirect effects (via health related symptoms and limitations) of CVRF's on depressive symptoms. Path analyses were estimated separately on four age groups: 50-64 years old, 65-74 years old, 75-84 years old, and 85 years and older. CVRF's and other comorbid medical conditions were highly predictive of health related symptoms and limitations across the four age groups. Health related symptoms and limitations were strongly linked to depressive symptoms and mediated the influence of medical illnesses (both vascular and nonvascular) on depressive symptoms. However, CVRF's exerted a unique effect on depressive symptoms in the oldest-old group (i.e., 85+). Among those over the age of 85, a greater number of CVRF's was associated with more severe depressive symptoms independent of health related symptoms/limitations and other comorbid medical conditions. Health related symptoms and limitations mediated the relationship between CVRF's and depression in individuals under 85. That is, the influence of vascular burden on depression is predominately indirect via health related limitations. But among those over the age of 85, vascular disease had a unique contribution on depression, even after controlling for other comorbid medical illness and health related limitations. This finding supports the vascular depression hypothesis and is consistent with prior work suggesting vascular disease may exert its greatest effect on depression in the context of increasing frailty.