Brain scanning markers help categorize risks of Alzheimer’s

Researchers have identified brain imaging benchmarks that could improve how doctors classify the risks of Alzheimer’s disease, especially among Hispanic and non-Hispanic white populations.

The study, which involved 675 older adults, established a specific threshold for tau accumulation that distinguished people with normal cognition from those who showed signs of cognitive impairment associated with Alzheimer’s disease.

These findings, published in imaging neuroscience, represent a key step in how standardization explains brain scans in different populations. Using an advanced imaging technique called Tau PET, scientists can now visualize abnormal TAU proteins by injecting small amounts of radiotracers, thereby promoting Alzheimer’s disease, highlighting the areas where these destructive proteins accumulate.

Accuracy of the brain memory center

The team focused on the medial temporal lobe, a brain area deep in the center of memory that includes areas that are critical for the formation and storage of memory. Cognitive impairment associated with Alzheimer’s disease is strongly indicated when tau protein levels in this region exceed a specific threshold (as a standardized uptake ratio of 1.26).

“Our tau tangent point distinguishes whether the study participants had cognitive impairment, but only if another abnormal protein, amyloid, was also present in people with cognitive impairment, and only in Hispanic and non-Hispanic white participants.”

The study used a newer imaging tracer called 18F-PI-2620, which has an advantage over earlier Tau tracers by reducing interference such as off-target binding in choroidal plexus (such as choroidal plexus). This improved accuracy allows researchers to more accurately measure TAU accumulation in specific brain regions that are most affected by Alzheimer’s disease.

Key research results:

• The medial temporal lobe threshold of 1.26 effectively identified cognitive impairment in Hispanic and white participants
• In non-Hispanic Black participants, the marker performed poorly, suggesting that other pathways may lead to cognitive decline
• Tau accumulation is most reliable when amyloid plaques are present
• The technology showed 93% specificity and 75% sensitivity to detect cognitive changes associated with Alzheimer’s disease

However, markers show disturbing limitations. Among non-Hispanic Black participants, tau thresholds were unable to reliably predict cognitive impairment, highlighting the dangerous gap in current diagnostic approaches.

“In non-Hispanic Black participants, the tau cutting point did not proceed as expected. This suggests that other pathology or conditions may promote cognitive decline in the group,” Brasky noted.

Different groups of people, different patterns

The most important contribution of the study is its diverse participant base – 186 Hispanic, 209 non-Hispanic blacks and 280 non-Hispanic white adults, with an average age of 64 years. This represents a departure from traditional Alzheimer’s study, historically focusing on the white population.

Victoria Tennant, a PhD candidate for the USC Neuroscience Graduate Program, highlighted the implication: “Our findings support previous research linking temporal lobe tau to cognitive impairment and establishing a 18F-PI-2620 layoff in the region, marking an important step in determining TAU enthusiasm to determine the efficiency of research and clinical applications.”

Research shows that the progress of Alzheimer’s disease follows different patterns of each ethnic group. The team found that 73% of participants with Hispanic cognitive impairment were all amyloid-negative, while 51% of non-Hispanic white participants may play a greater role in cognitive decline in some populations.

These findings could reshape how clinical trials are designed and how doctors interpret brain scans in diverse patient populations. This work forms part of the brain study of health and aging – health differences, the most comprehensive study of Alzheimer’s disease among different communities, which has produced key findings on racial changes in disease biomarkers and social determinants of cognitive health.

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