New Tau PET Imaging Technique Reveals Alzheimer's Risk Disparities

Researchers from the Keck School of Medicine at the University of Southern California (USC) have unveiled a promising brain imaging technique that may enhance the ability to predict Alzheimer's disease (AD) risk. The study, published in Imaging Neuroscience on June 29, 2025, identifies a tau-based biomarker that works effectively in Hispanic and non-Hispanic White populations but reveals notable limitations for non-Hispanic Black individuals, raising concerns about health disparities in Alzheimer's diagnostics.

The research is part of the Health and Aging Brain Study-Health Disparities (HABS-HD), a collaborative effort involving multiple universities and supported by the National Institute on Aging. Using advanced tau positron emission tomography (tau PET), the researchers analyzed brain scans from over 675 older adults to establish tau cut-points that indicate clinically relevant changes associated with Alzheimer's disease.

According to Dr. Meredith N. Braskie, an assistant professor of neurology at USC and senior author of the study, "Our tau cut-point was able to distinguish whether study participants had cognitive impairment - but only when another abnormal protein, amyloid, was also present in those with cognitive impairment, and only in Hispanic and non-Hispanic White participants." This finding underscores the necessity for more inclusive research that addresses the biological and social factors influencing Alzheimer’s disease susceptibility across diverse populations.

The study highlights the use of the 18F-PI-2620 imaging tracer to visualize tau protein accumulation in the brain. The researchers found that elevated tau levels in the medial temporal lobe were strongly correlated with cognitive impairment related to Alzheimer's disease. Dr. Victoria R. Tennant, a PhD candidate in USC's Neuroscience Graduate Program and lead author, stated, "While our findings support prior research linking medial temporal lobe tau to cognitive impairment, establishing a cut-point in this region using 18F-PI-2620 marks an important step toward defining tau positivity for both research and clinical applications."

Despite the advancements in tau PET imaging, the study's results indicate that the tau biomarker may not be as reliable for non-Hispanic Black participants, suggesting that further research is needed to explore alternative biological markers or pathologies affecting cognitive decline within this demographic. This limitation emphasizes the importance of conducting future clinical trials that reflect a wider range of ethnic and racial diversity to ensure equitable healthcare outcomes.

The implications of these findings extend to the broader field of Alzheimer's research, which aims to refine diagnostic tools and treatments for the disease. As Dr. Arthur W. Toga, director of the Stevens Neuroimaging and Informatics Institute, noted, "These findings are just the latest to come from HABS-HD, which is the most comprehensive study of Alzheimer's disease and related dementias in diverse communities. We hope this work will lead to more personalized care and better outcomes for all communities."

In conclusion, while the new tau PET imaging technique represents a significant advancement in Alzheimer's diagnostics, it also highlights critical gaps in the current understanding of the disease across different populations. Continued efforts to include diverse cohorts in research will be essential in developing effective diagnostic and treatment strategies that address the needs of all individuals affected by Alzheimer’s disease.