MRI markers of brain aging and risk factors for cognitive decline in older African Americans

ABSTRACT
The aging research community has identified numerous risk factors associated with the full spectrum of
cognition including mild cognitive impairment and Alzheimer’s disease (AD), and there is greater understanding
of the underlying brain mechanisms. Unfortunately, the vast majority of knowledge comes from studies of
primarily non-Hispanic Whites. Although African Americans bear a disproportionate burden of Alzheimer’s
disease (AD) and cognitive impairment, the neurobiologic mechanisms underlying these disparities remain
elusive. The overall goal of the proposed study is to investigate the underlying neurobiologic
mechanisms linking culturally-relevant psychosocial risk factors to cognitive decline and risk of AD in
older African Americans. Existing literature with MRI data in older African Americans has focused almost
exclusively on cross-sectional associations of cognition or incident AD, and has examined traditional risk
factors. Very few studies of African Americans have examined culturally relevant risk factors with repeated
measures of cognitive function and brain integrity over time to test the underlying neurobiologic mechanisms
linking risk factors to cognitive decline and risk of AD. We propose to interrogate changes in structural and
functional integrity on MRI as key neurobiologic substrates linking these socially relevant risk factors to
cognitive decline and risk of AD in African Americans. Leveraging the well-established infrastructure of the
Minority Aging Research Study (MARS), including available data on risk factors, and repeated measures of
cognitive function, we will use a multi-modal neuroimaging approach to acquire antemortem MRI scans on 400
African Americans and quantify change in a number of brain MRI indices to address the Specific Aims. Aim 1
will examine the relation of change in brain MRI indices with rate of cognitive decline and risk of AD among
older African Americans; Aim 2 will examine the relation of early and mid-life cultural risk factors with change in
structural and functional brain MRI indices among older African Americans; Aim 3 will determine if change in
brain MRI indices affects the relation of early- and mid-life risk factors to rate of decline and risk of AD among
older African Americans; and taking advantage of neuroimaging and cognitive function data available at no
cost from the Rush Memory and Aging Project (MAP), Aim 4 will identify racial differences in the relation of
change in MRI structural and functional brain integrity to cognitive decline. Cognitive impairment associated
with aging is a large and growing public health problem that disproportionately burdens African Americans.
Knowledge of the neurobiologic pathways linking risk factors to cognitive decline will ultimately provide targets
for future prevention/intervention studies, and will have a strong and sustained impact on the field.

Grant Number: 5R01AG056405-05
NIH Institute/Center: NIH
Principal Investigator: Lisa Barnes