2024 Health Disparities, Policy and Ethics in Alzheimer’s Disease and Dementia Research (HPE-ADRD)

Impact of Genetic and Ethnic Risk Factors on Early Imaging Biomarkers of AD

How do early-stage brain changes linked to Alzheimer’s take place in Hispanic individuals?

Stephanie Leal, M.D.
University of California, Los Angeles
Los Angeles, CA - United States

Background

According to the 2024 Alzheimer’s Association Facts and Figures Report, older Hispanic Americans are about one and one-half times as likely to develop Alzheimer’s or other dementia as older White Americans. Studies also show that the broad Hispanic American community does share certain factors related to Alzheimer’s risk. For example, Hispanic Americans tend to develop Alzheimer’s symptoms earlier than White Americans; and APOE-e4 (a genetic variation associated with Alzheimer’s) does not increase Alzheimer’s risk in Hispanic individuals as much as it does in Whites. These findings suggest the need for more research to better understand the differences in how Alzheimer’s develops in Hispanic Americans.  

Research Plan

Dr. Stephanie Leal and colleagues plan to examine Alzheimer’s risk in the Hispanic American community by focusing on two factors: episodic memory (or memory of experiences across time) and brain changes in the medial temporal lobe (a brain region affected early in Alzheimer’s disease). For this effort, they will recruit a group of 140 older Hispanic and non-Hispanic adults from the Houston area, some of whom will have APOE-e4 and some of whom will have other APOE variations. They will then administer a novel test designed to measure episodic memory loss. The test will involve memorizing images that are culturally relevant to the Hispanic community, and then distinguishing those images over time from other, similar-looking images. As this test is administered, the researchers will use cutting-edge magnetic resonance imaging (MRI) scans to look for dementia-related changes in the participants’ hippocampus and locus coeruleus (two areas of the medial temporal lobe). These changes include abnormal levels of neuromelanin (a compound associated with loss of function in the locus coeruleus) and abnormal brain cell activity in the hippocampus. Dr. Leal’s team will compare how performance on the memory test, as well brain changes observed during the test, differ among Hispanics and non-Hispanics. They will also assess differences among those with and without APOE-e4.  

Impact

Dr. Leal’s study could help clarify the biological and genetic mechanisms underlying memory loss and dementia risk in the Hispanic American community. Ultimately, such work could lead to novel methods of diagnosing Alzheimer’s at an early stage in this underserved population.