A team of researchers from the Keck School of Medicine of USC has identified a new brain imaging benchmark that could enhance the classification of Alzheimer’s disease-related changes, particularly in Hispanic and non-Hispanic white populations. The study, published in Imaging Neuroscience, is part of the Health and Aging Brain Study–Health Disparities (HABS-HD), a collaborative effort supported by the National Institute on Aging.
Using an advanced brain scan called tau PET, the researchers analyzed over 675 older adults to determine a threshold for tau protein accumulation linked to cognitive impairment. Tau PET scans utilize a radioactive tracer to highlight abnormal tau proteins in the brain, which are associated with Alzheimer’s disease. The team established a tau “cut-point”—a biomarker threshold that indicates higher Alzheimer’s risk—but found it was only effective under specific conditions.
The cut-point successfully distinguished cognitive impairment in participants when another abnormal protein, amyloid, was also present, but this correlation was limited to Hispanic and non-Hispanic white individuals. For non-Hispanic Black participants, the tau cut-point did not perform as expected, suggesting other factors may contribute to cognitive decline in this group.
“Our findings highlight the need to consider diverse populations in Alzheimer’s research,” said senior author Meredith N. Braskie, PhD. “While tau is a key marker, its relationship with cognitive impairment varies across ethnic groups.”
The study employed a novel tracer, 18F-PI-2620, to measure tau buildup in the medial temporal lobe, a brain region critical for memory. Exceeding a certain tau threshold in this area strongly indicated Alzheimer related cognitive impairment.
Lead author Victoria R. Tennant emphasized the importance of the findings for future research and clinical applications, while also noting the limitations in non-Hispanic Black populations. The study underscores the need for further investigation into the biological and social determinants of Alzheimer’s disease.
Arthur W. Toga, PhD, director of the Stevens INI, highlighted the broader implications of the research: “This work advances our understanding of Alzheimer’s risk and progression, paving the way for more personalized care and better outcomes for all communities.”
The study reflects ongoing efforts to ensure diagnostic tools are effective across diverse populations, addressing gaps in current Alzheimer’s research.
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