New Tau PET Imaging Cut-Point Enhances Alzheimer’s Diagnosis Accuracy

A groundbreaking study conducted by researchers at the Keck School of Medicine of the University of Southern California (USC) has revealed a new tau PET imaging cut-point that significantly enhances the diagnosis of Alzheimer’s disease (AD) among diverse populations, particularly Hispanic and non-Hispanic white individuals. Published in the journal Imaging Neuroscience on June 27, 2025, this research is part of the ongoing Health and Aging Brain Study–Health Disparities (HABS-HD), which aims to address disparities in Alzheimer’s disease diagnosis and treatment across different ethnic groups.

The research team, led by Dr. Meredith N. Braskie, an assistant professor of neurology at USC, analyzed tau PET scans from over 675 older adults participating in the HABS-HD study. Tau PET imaging enables the visualization of tau proteins, which are implicated in the progression of Alzheimer’s disease. By utilizing a novel radioactive tracer, 18F-PI-2620, the researchers established a specific tau cut-point that could indicate the presence of clinically relevant biological markers of Alzheimer’s disease.

Dr. Braskie noted, “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 tailored diagnostic criteria that consider ethnic variations in Alzheimer’s disease manifestations.

Despite the promising results, the study identified limitations in the tau cut-point's effectiveness among non-Hispanic Black participants, suggesting that additional factors may contribute to cognitive decline in this demographic. Dr. Victoria R. Tennant, a PhD candidate at USC and lead author of the study, emphasized the importance of including diverse populations in Alzheimer’s research. “While our findings support prior research linking medial temporal lobe tau to cognitive impairment, 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,” she stated.

The implications of this research extend beyond diagnosis to potential clinical applications. Dr. Arthur W. Toga, director of the Stevens Neuroimaging and Informatics Institute, remarked, “This type of imaging is critical for understanding who is at risk and how the disease develops.” The findings from this study contribute to a growing body of literature focused on improving diagnostic tools and ensuring they are effective for all populations, not just those represented in clinical trials.

Alzheimer’s disease progresses in stages, with amyloid plaques forming early in the disease process and tau tangles closely associated with memory loss and other cognitive symptoms. The ability to establish tau cut-points may lead to more accurate assessments of cognitive health and inform treatment strategies tailored to individual patient needs, ultimately enhancing the quality of care for diverse communities affected by Alzheimer’s disease.

The Health and Aging Brain Study has already produced significant findings related to ethnic variations in Alzheimer’s biomarkers and the influence of social determinants on cognitive health. As research continues, there is hope that these advancements will lead to more personalized care and improved outcomes for all communities facing the challenges of Alzheimer’s disease.

The study, titled “Establishing tau-PET cut-points for cognitive diagnosis with 18F-PI-2620 in a multi-ethnoracial cohort,” is available in Imaging Neuroscience, volume 3, article IMAG.a.41, DOI: 10.1162/IMAG.a.41. The ongoing research emphasizes the importance of collaborative efforts to address health disparities and improve diagnostic precision in Alzheimer's disease management.