Subtle changes in how blood flows through the brain may be an early warning sign of Alzheimer’s disease, according to new research from the Mark and Mary Stevens Neuroimaging and Informatics Institute (Stevens INI) at the Keck School of Medicine of USC. The study, published February 24, 2026, in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, suggests that assessing brain blood flow and oxygen levels could offer a new avenue for identifying individuals at risk years before cognitive symptoms appear. This research builds on growing understanding of Alzheimer’s disease, which affects more than 7 million Americans, according to the Alzheimer’s Association.
Researchers found a link between noninvasive measures of brain blood flow and oxygenation and hallmarks of Alzheimer’s, including the buildup of amyloid plaques and a reduction in the size of the hippocampus, a brain region crucial for memory. These findings suggest that the health of the brain’s vascular system—the network of blood vessels—plays a significant role in the early stages of the disease process. Understanding this connection could lead to earlier diagnosis and potentially new prevention strategies for this devastating condition.
The study examined older adults with and without cognitive impairment, utilizing two readily available and painless techniques. Transcranial Doppler ultrasound measures the speed of blood flow in major brain arteries, whereas near-infrared spectroscopy assesses how effectively oxygen reaches brain tissue. By combining these measurements with advanced mathematical modeling, the researchers created indicators of cerebrovascular function, reflecting the brain’s ability to adjust blood flow and oxygen delivery in response to natural fluctuations.
Vascular Health and Alzheimer’s Biomarkers
Participants with healthier vascular indicators—those resembling patterns seen in cognitively healthy adults—tended to have lower levels of amyloid and a larger hippocampus. Amyloid plaques are protein deposits that accumulate in the brains of people with Alzheimer’s, and hippocampal shrinkage is a well-established marker of cognitive decline. “These vascular measures are capturing something meaningful about brain health,” said Meredith N. Braskie, PhD, senior author of the study and assistant professor of neurology at the Keck School of Medicine. “They appear to align with what we see on MRI and PET scans that are commonly used to study Alzheimer’s disease, providing critical information about how vascular health and standard brain measures of Alzheimer’s disease risk may be related.”
The research team also observed that individuals diagnosed with mild cognitive impairment or dementia exhibited weaker vascular function compared to those with normal cognitive abilities. This supports the idea that declining blood vessel health in the brain is an integral part of the broader Alzheimer’s disease continuum. The findings add to a growing body of evidence suggesting that Alzheimer’s is not solely a neurodegenerative disease, but also involves significant vascular contributions.
A New Approach to Early Detection?
Currently, diagnosing Alzheimer’s often relies on expensive and complex imaging techniques like MRI and PET scans. The methods used in this study—transcranial Doppler ultrasound and near-infrared spectroscopy—offer a potentially more accessible and affordable alternative. They don’t involve injections, radiation exposure, or demanding tasks for patients, making them suitable for large-scale screening or for individuals who may not be able to undergo more intensive brain imaging.
“If we can track these signals over time, we may be able to identify people at higher risk earlier and test whether improving vascular health can slow or reduce Alzheimer’s-related brain changes,” said Amaryllis A. Tsiknia, lead author of the study and a USC PhD candidate.
The Role of Blood Flow and Oxygen
Arthur W. Toga, PhD, director of the Stevens INI, emphasized the importance of understanding the interplay between blood flow, oxygen regulation, and the classic hallmarks of Alzheimer’s—amyloid and tau proteins. “Understanding how blood flow and oxygen regulation interact with amyloid and brain structure opens new doors for early detection and potentially prevention,” Toga said. The Stevens INI is also home to the Global Alzheimer’s Association Interactive Network (GAAIN), a data-sharing platform designed to accelerate Alzheimer’s research worldwide.
Still, the researchers caution that their findings represent a snapshot in time and do not prove a cause-and-effect relationship. Ongoing longitudinal studies are tracking participants to determine whether changes in these vascular measures can predict future cognitive decline or response to treatment. The team is also investigating whether interventions aimed at improving vascular health—such as diet, exercise, and blood pressure control—can mitigate Alzheimer’s risk.
This research was supported by the Office of The Director, National Institutes of Health, under Award Number S10OD032285, and by the National Institute on Aging [R01AG058162].
Disclaimer: This article provides information for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
The researchers plan to continue monitoring participants to assess the predictive power of these vascular measures over time. The next phase of the study will focus on identifying specific lifestyle factors that can improve brain blood flow and potentially reduce the risk of Alzheimer’s disease. Readers interested in learning more about Alzheimer’s disease and participating in research studies can visit the Alzheimer’s Association website.
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