New Imaging Benchmark Enhances Alzheimer's Detection in Diverse Groups

A groundbreaking study conducted by researchers at the Keck School of Medicine at the University of Southern California (USC) has unveiled a new brain imaging benchmark that promises to significantly improve the classification of biologically meaningful alterations associated with Alzheimer's disease (AD). This advancement is particularly impactful for Hispanic and non-Hispanic white populations, as it aims to enhance diagnostic accuracy across diverse demographic groups.

The study, published on June 26, 2025, in the journal *Imaging Neuroscience*, is part of the Health and Aging Brain Study–Health Disparities (HABS-HD), a multi-university collaboration spearheaded by the University of North Texas Health Science Center and funded by the National Institute on Aging. Researchers employed an advanced imaging technique known as tau positron emission tomography (tau PET) to investigate over 675 older adults, focusing on discerning the optimal brain signal that differentiates individuals exhibiting clinically significant biological markers of Alzheimer's from those aging normally.

Tau PET allows for the visualization of tau proteins, which are implicated in the development of Alzheimer's disease. Utilizing a specialized radioactive tracer, the research team established tau cut-points—new biomarkers that indicate whether tau protein levels in the brain are concerningly elevated, suggesting early signs of Alzheimer's or related conditions.

Meredith N. Braskie, PhD, a senior author and assistant professor of neurology at USC, explained, "Our tau cut-point successfully distinguished cognitive impairment among participants only when abnormal amyloid protein levels were also present in those with cognitive impairment, specifically in Hispanic and non-Hispanic White participants. This finding indicates a potential disparity in the pathologies driving cognitive decline among different ethnic groups, especially among non-Hispanic Black participants, where the tau cut-point did not yield expected results."

This revelation underscores the necessity for more inclusive research methodologies that encompass diverse populations to fully understand the complexities surrounding Alzheimer's disease. The study utilized a novel imaging tracer, 18F-PI-2620, which enabled researchers to measure tau protein accumulation in the brain. They noted that high tau levels in the medial temporal lobe—a brain region crucial for memory—strongly correlated with cognitive impairment associated with Alzheimer's disease.

Victoria R. Tennant, the lead author and a PhD candidate in USC's Neuroscience Graduate Program, emphasized the importance of establishing a reliable cut-point for tau levels, stating, “While our findings support earlier studies linking medial temporal lobe tau to cognitive impairment, this research marks a significant step towards defining tau positivity for both clinical and research purposes. Nevertheless, the limited reliability of tau as a cognitive impairment indicator in non-Hispanic Black participants highlights the critical need for diverse populations in future Alzheimer’s studies.”

The implications of this research are profound, as they reflect a growing commitment within Alzheimer's research to develop diagnostic tools that are applicable to all populations, rather than limiting studies to narrow clinical trial demographics. Alzheimer’s disease progresses through various stages, with amyloid plaques typically forming early while tau tangles are more closely associated with memory loss and other symptoms.

Arthur W. Toga, PhD, director of the Stevens INI, remarked, "This type of imaging is essential for identifying at-risk individuals and understanding disease development. The findings from HABS-HD, the most comprehensive study of Alzheimer’s disease and related dementias in ethnically diverse communities, have already contributed to pivotal insights concerning ethnic variations in AD biomarkers and the influence of social determinants on cognitive health. We aspire for this research to lead to more personalized care and improved outcomes for all communities."

The study not only advances the field of Alzheimer's research but also sets a precedent for future investigations that prioritize diversity in clinical research and seek to unravel the multifaceted nature of Alzheimer's disease across different populations. As the search for effective diagnostic and therapeutic interventions continues, the need for research that accurately reflects the demographic diversity of affected populations has never been more critical.