BOSTON — Why do Black/African-American (AA) individuals have a higher risk of Alzheimer’s disease (AD) than white non-Hispanic persons of European ancestry (EUR)?
That question was addressed in a recent review in the Journal of Clinical Medicine.1
VA Boston Healthcare System-led authors suggested the reasons might include economic disparities, cardiovascular health, quality of education and biases in the methods used to diagnose AD.
They also pointed out that AD is heritable, and some of the differences in risk might be due to genetics. Many AD-associated variants have been identified by candidate gene studies, genomewide association studies (GWAS) and genome-sequencing studies.
“However, most of these studies have been performed using EUR cohorts. In this paper, we review the genetics of AD and AD-related traits in AA individuals,” the study authors wrote. “Importantly, studies of genetic risk factors in AA cohorts can elucidate the molecular mechanisms underlying AD risk in AA and other populations. In fact, such studies are essential to enable reliable precision medicine approaches in persons with considerable African ancestry. Furthermore, genetic studies of AA cohorts allow exploration of the ways the impact of genes can vary by ancestry, culture, and economic and environmental disparities. They have yielded important gains in our knowledge of AD genetics, and increasing AA individual representation within genetic studies should remain a priority for inclusive genetic study design.”
Alzheimer’s disease (AD) is the most common form of dementia, comprising 60-80% of dementia cases and is nearly twice as prevalent in Black/AA individuals compared to white non-Hispanic/EUR individuals, according to background information in the article.
“The reasons for this disparity in risk are not fully understood,” according to the analysts. “For example, the prevalence of AD in AA individuals may be inflated due to biases in the methods for cognitive testing, which may systematically yield lower ratings in AA seniors The AA population also carries a higher burden of poor cardiovascular health and diabetes which are AD risk factors. Differences in education quality and environmental stressors related to economic disparities likely also contribute to the increased risk of AD in AA individuals.”
Genetic factors were the focus of the review, and the authors advised that it is “important to acknowledge that differences observed between studies in AA cohorts and EUR cohorts are not necessarily due to differences in the effects of specific variants but rather may represent a complex interaction between SDOH and genetics.”
They pointed out that European cohorts are vastly overrepresented in genetic studies compared to other ancestry groups, adding, “This difference limits our understanding of the genetic basis of AD in non-EUR populations because the impact of particular genetic loci on AD can vary by ancestry.”
The reviewers also described how epidemiological studies comparing the risk of AD in EUR and AA families have found important differences and commonalities. “Compared to individuals without AD, relatives of AD cases had an overall 1.5 times increased risk of AD in both AA and EUR families,” they wrote.
- Logue MW, Dasgupta S, Farrer LA. Genetics of Alzheimer’s Disease in the African American Population. J Clin Med. 2023 Aug 9;12(16):5189. doi: 10.3390/jcm12165189. PMID: 37629231; PMCID: PMC10455208.