In the largest genetic study ever conducted on dementia in people of African descent, VA researchers identified several different genetic risks than those seen in people of European descent.
Using data from the VA Million Veteran Program (MVP), the team found several cases in which genetic variants may increase the risk of Alzheimer’s disease and related dementias.
The findings appear in the December 22, 2022 issue of Molecular Psychiatry.
“MVP represents an incredible resource for examining the genetics of many diseases, including dementia“said study author Dr. Mark Logue, a statistician with the Boston VA Health Care System and the National Center for PTSD. “This study is one of the first Alzheimer’s disease-related studies to emerge from MVP. My colleagues and I are working hard to increase the dementia work at MVP and to partner with other large-scale studies on Alzheimer’s disease and dementia.
“The results signify a substantial increase in knowledge of the genetic architecture of dementia risk in populations of African descent,” Logue said.
In the United States, a higher proportion of African Americans have Alzheimer’s disease than people of European descent; however, most of the large genetic studies of Alzheimer’s disease study white participants. While there are genes implicated in Alzheimer’s that are consistent across different populations, the researchers explained in the study that specific variants may differ by ancestry. That means study results using only one ethnic group may not apply to other groups, making dementia prevention and treatment more difficult. For example, studies have found that a genetic variant called APOE E4 carries the highest genetic risk of Alzheimer’s disease in people of European descent, but the effect of APOE E4 is half as strong in people of African descent.
Increase the representation of populations of non-European descent in genome-wide association studies it has been identified as a critical scientific and equity issue in genetic studies. According to the study, the difference in sample sizes between studies of European and non-European ancestry to date could even contribute to health disparities in minority populations.
To address this disparity, the Boston VA researchers compared the genomes of more than 4,000 MVP participants of African descent who had dementia with more than 18,000 veterans without dementia. The team also conducted a second analysis comparing 7,000 black MVP participants who reported their parents had dementia with another 56,000 whose parents did not have dementia. This sample is more than twice the size of the previous largest Alzheimer’s genetic study of individuals of African descent.
The results showed an association between dementia risk and variants in six different genes, including APOE. While many of these genes have been linked to dementia in previous genetic studies of people of European ancestry, only two of them have been identified as significant risk factors in people of African ancestry.
While many of the gene variants identified in this study were linked to dementia in groups, the particular gene variants linked to dementia risk were different between people of African and European descent, meaning that different forms of the same gene may affect a person’s dementia risk based on their career.
These new findings will help close the gap in knowledge of Alzheimer’s risk by ancestry, the researchers said. Identification of population-specific genetic risk factors will lead to more accurate risk assessment in people of African descent and could also reveal new molecular targets for developing drugs to treat Alzheimer’s disease.
With more than 900,000 participants to date, MVP is one of the largest genetic research programs in the world. MVP researchers collect genetic data as well as information about health, lifestyle, and military exposures to understand how genes affect health and disease.
MVP is also one of the most diverse genetic programs in the world. More than 150,000 African American veterans have volunteered to join MVP, representing 18% of all participants. This means that MVP includes more people from Africa ancestry than any other biobank in the world. Thanks to its diversity and the altruism of participating veterans, MVP is working to close the racial gap in the link between genetics and disease.
“MVP’s sheer size as one of the world’s largest genetic databases means it can really boost what is known about how genes influence dementia risk,” said Logue. “Working on the MVP data is an exciting opportunity for a researcher like myself, and I am grateful to all the veterans who agreed to participate in this study.”
GWAS of African Descent Dementia in a Large Military Cohort Identifies Significant Risk Loci, Molecular Psychiatry (2022). DOI: 10.1038/s41380-022-01890-3
Provided by Veterans Affairs Research Communications
Citation: New Study Reveals Dementia Risks Unique to People of African Descent (December 22, 2022) Accessed December 22, 2022 at https://medicalxpress.com/news/2022-12-reveals-dementia-unique -people-african.html
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