Alzheimer’s Blood Marker Varies Across Racial and Ethnic Groups
A study of 15,612 adults finds population differences in an Alzheimer’s blood marker, highlighting questions about early screening.
Summary
A blood marker used to screen for Alzheimer’s disease showed different average levels across racial and ethnic groups in a large study. Researchers analyzed 15,612 adults aged 55 to 80 who underwent screening for a prevention trial program. Asian, Black, and Hispanic participants had lower marker levels than White and non-Hispanic comparison groups. A genetic variant associated with Alzheimer’s risk was linked to higher levels in every group, but the strength of that relationship varied. The marker’s relationships with memory and thinking scores and brain scans showed no significant differences between racial groups, although differences appeared by ethnicity. The findings support further evaluation of blood screening followed by confirmatory scans, not routine testing of adults without symptoms. This snapshot study cannot explain the differences or predict future dementia, and this summary uses only the abstract.
Detailed Summary
Blood tests that flag Alzheimer’s disease biology before symptoms could help researchers recruit participants for prevention trials. But their interpretation must be reliable across populations. This study examined phosphorylated tau 217 percentage, a blood measure associated with brain changes seen in Alzheimer’s disease. Understanding variation matters because screening thresholds could influence who proceeds to brain scans and potential trial enrollment.
Researchers analyzed screening data from 15,612 adults aged 55 to 80 in the AHEAD 3-45 trial program. Participants were assessed at 106 sites across four world regions between July 2020 and October 2024. Their average age was 68.4 years, and 63.7% were women. Analyses compared blood results with cognitive test scores and amyloid brain scans, accounting for measured factors using regression.
Asian, Black, and Hispanic participants had lower blood biomarker levels than White and non-Hispanic comparison groups. Carrying APOE ε4, a genetic variant linked to Alzheimer’s risk, was associated with higher levels across all groups. However, the strength of that relationship varied by race and ethnicity. These findings describe group averages and associations, not a biological explanation for the observed differences.
Relationships between the blood marker and cognition or amyloid scans showed no significant pairwise differences across racial groups. Differences did emerge by Hispanic versus non-Hispanic ethnicity, including interactions with APOE ε4 status. The authors interpret the racial findings as supporting blood screening followed by confirmatory imaging, while emphasizing that the ethnicity findings need further study before their implications are clear.
For clinicians, the study highlights the importance of validating screening approaches in diverse populations rather than assuming identical biomarker distributions. It does not establish new diagnostic cutoffs or recommend routine testing of adults without symptoms. This was a cross-sectional analysis of trial volunteers, so it cannot establish causation or predict future dementia. This summary relies on the published abstract only.
Key Findings
- Among 15,612 adults, Asian, Black, and Hispanic participants had lower average %p-tau217 levels than White and non-Hispanic comparison groups.
- APOE ε4 carriage was associated with higher %p-tau217 in every group, but the association varied by race and ethnicity.
- Biomarker associations with cognition and amyloid PET showed no significant pairwise differences across racial groups.
- Ethnicity-related differences warrant further investigation; the findings do not establish population-specific screening thresholds.
- The authors support blood-based trial screening followed by PET confirmation, not using the blood result alone.
Methodology
This cross-sectional analysis used AHEAD 3-45 screening data collected at 106 sites across four world regions from July 2020 through October 2024. It included 15,612 adults aged 55–80 whose %p-tau217 was measured before medical and cognitive exclusions. Multivariable linear regression assessed associations involving self-reported race and ethnicity, APOE ε4 status, cognitive scores, and amyloid PET.
Study Limitations
This summary is based on the abstract only; detailed adjustment variables, subgroup sizes, and diagnostic performance measures were unavailable. The cross-sectional design cannot establish causation or predict progression to dementia, and trial-screening volunteers may not represent the general population. Nonsignificant racial comparisons do not prove equivalent test performance, and self-reported race and ethnicity do not explain the observed differences.
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