Author ORCID Identifier

https://orcid.org/0000-0002-7961-5731

Date of Award

8-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Vonetta Dotson, Ph.D.

Abstract

Black older adults have a higher prevalence of vascular conditions (e.g., heart disease) and greater cerebrovascular disease burden compared to Whites. Decreased brain white matter integrity as a result of vascular burden is associated with a form of late-life depression, known as vascular depression (VaDep), which is marked by chronic vascular risk, executive dysfunction, poor treatment response, and high levels of functional disability. Older Black adults may be particularly vulnerable to developing VaDep; however, the literature examining VaDep in Black older adults is sparse. The present study used publicly available data from the Healthy Brain Project, a substudy of the Health, Aging, and Body Composition Study that includes imaging, cognitive, and gait speed data, to test the VaDep hypothesis in a community sample of Black older adults followed for four years.

Multiple regression analyses revealed that total and uncinate fasciculus white matter hyperintensity (WMH) volume, but not clinically-defined vascular burden, predicted depressive symptoms (as measured by the Center for Epidemiologic Studies Depression Scale) both cross-sectionally and longitudinally. Mixed effects regressions compared cognitive performance (Digit Symbol Substitution Test [DSST] and 15-Item Executive Interview [EXIT-15]) and gait speed over four years between vascular depression, non-vascular depression, vascular-only, and healthy groups. The VaDep group had the slowest performance on the DSST at baseline and over time. The non-vascular depression group’s EXIT-15 performance improved over time while other groups (including VaDep) remained stable. Both the VaDep and non-vascular depression groups’ gait speed declined over time. Exploratory analyses revealed a stronger association between depression and uncinate fasciculus WMH in Black compared to White individuals, and showed that the Black VaDep group had the slowest DSST performance at baseline compared to all other race and vascular/depression groups. This research supports the validity of the VaDep framework in older Black adults, highlights WMH in the uncinate fasciculus as particularly relevant in identifying Black older adults who are at risk for developing depressive symptoms, and identifies cognitive risks associated with VaDep in older Black adults. It also addresses an important gap in the VaDep literature by examining a group that has historically been underserved.

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