New Tau PET Imaging Benchmark Enhances Alzheimer's Disease Classification

A research team from the Keck School of Medicine at the University of Southern California (USC) has unveiled a groundbreaking brain imaging benchmark that could significantly enhance the classification of Alzheimer's disease (AD)-related biological changes, particularly in Hispanic and non-Hispanic white populations. The findings, published in the peer-reviewed journal Imaging Neuroscience on June 27, 2025, arise from a comprehensive study involving over 675 older adults in the Health and Aging Brain Study–Health Disparities (HABS-HD), a multi-university initiative supported by the National Institute on Aging.

The research utilized an advanced imaging technique known as tau positron emission tomography (tau PET) to visualize tau protein accumulation in the brain, a hallmark of Alzheimer's disease. This innovative approach involved the use of the radioactive tracer 18 F-PI-2620, which highlights regions where tau has accumulated, allowing researchers to establish tau cut-points—specific thresholds that indicate clinically relevant biological markers of Alzheimer's disease.

Dr. Meredith N. Braskie, the senior author of the study and an assistant professor of neurology at USC, emphasized the importance of these findings, stating that the tau cut-point was effective in distinguishing cognitively impaired individuals from healthy participants, but only under certain conditions. "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," Dr. Braskie explained. The study revealed that higher tau levels were particularly evident in memory-associated areas of the brain, specifically the medial temporal lobe, indicating a strong correlation with cognitive impairment.

However, the results also highlighted a significant limitation: the tau cut-point was less effective in non-Hispanic Black participants, raising questions about the biological and social determinants affecting cognitive decline in this demographic. Victoria R. Tennant, the lead author and a Ph.D. candidate in USC's Neuroscience Graduate Program, advocated for increased diversity in research, stating, "the limited reliability of tau as an indicator of cognitive impairment in non-Hispanic Black participants highlights the need for more diverse populations in research and for future studies to examine both biological and social determinants of Alzheimer's disease."

The study's implications extend beyond the immediate findings, as it points to the necessity for more inclusive clinical trials that represent diverse populations affected by Alzheimer's disease. The director of the USC Stevens Neuroimaging and Informatics Institute, Dr. Arthur W. Toga, reiterated the importance of this research, remarking, "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."

The HABS-HD initiative not only aims to identify biomarkers for Alzheimer's disease but also addresses the significant variations in disease manifestation across different ethnic groups. Previous studies stemming from HABS-HD have explored these variations, including the influence of social determinants on cognitive health and the vascular contributions to dementia.

The current findings substantiate existing research linking tau accumulation in the medial temporal lobe to cognitive decline but mark a pivotal step in defining tau positivity for both research and clinical applications. The establishment of tau cut-points promises to refine diagnostic protocols and enhance early intervention strategies for Alzheimer's disease, underscoring the critical nature of imaging in understanding the disease's progression and risk factors.

In summary, the new tau PET imaging benchmark represents a significant advancement in the classification of Alzheimer's disease-related changes, with the potential to improve diagnostic accuracy and foster personalized treatment approaches. Future research will undoubtedly benefit from a continued emphasis on diversity and inclusivity, ensuring that all populations can receive appropriate care and interventions in the face of this pervasive condition.

For further details, the full study can be accessed in Imaging Neuroscience, DOI: 10.1162/IMAG.a.41.