USC Study Exposes Hidden Culprit of Dementia in Brain’s Blood Vessels

A new USC-led study suggests that assessing blood vessel health should be included in dementia diagnostics.

A new USC-led study has found that mild cognitive impairment is associated with blood vessel dysfunction in the brain’s temporal lobes, the region responsible for memory.

This vascular issue was observed in individuals both with and without amyloid buildup in the brain, indicating that microvascular dysfunction could serve as an early biomarker for dementia and a potential target for treatment.

The study, conducted by researchers from several universities, was published in the journal Neurology.

“We’re studying the ability of these very small vessels to respond to stimuli and to dilate, and they’re showing dysfunction in people who have memory problems,” said senior author Daniel Nation, a professor of gerontology and medicine at the USC Leonard Davis School of Gerontology. “It could implicate blood vessel dysfunction in a very early stage of memory loss. It happened whether or not people had Alzheimer’s-related brain changes. They still had this blood vessel problem if they had memory issues.”

New biomarker for dementia

For the study, researchers recruited a sample of 144 older, independently living adults from the community. The volunteers took a neuropsychological assessment, gave blood samples and underwent brain MRI, or magnetic resonance imaging.

During MRI, volunteers held their breath for 15-second intervals, an exercise designed to dilate the brain’s blood vessels, a natural process called “cerebrovascular reactivity” which regulates oxygen levels in the brain.

Researchers paid special attention to blood vessels supplying the temporal lobes, located on the sides of the head, near the ears. Participants whose blood vessels didn’t dilate properly showed signs of cognitive impairment.

“With this approach, we can pinpoint the problem to the blood vessels and their ability to dilate. That’s not the way people usually think about memory impairment in older adults,” Nation said. “There’s an increasing realization that the main cause of dementia is not actually Alzheimer’s disease, it’s mixed pathology. If you just focus on amyloid, you’re certainly not going to get the full picture. Maybe this technique should be incorporated into our diagnostic approaches.”

“Our findings underscore the need to focus on vascular health as a critical factor in memory decline,” said first author Arunima Kapoor, a graduate student at the University of California, Irvine.

Nation said that some blood pressure drugs may potentially protect vascular function in a way that preserves memory, but more research is needed.

Reference: “Association of Medial Temporal Lobe Cerebrovascular Reactivity and Memory Function in Older Adults With and Without Cognitive Impairment” by Arunima Kapoor, Shubir Dutt, Allison C. Engstrom, John Paul M. Alitin, Trevor Lohman, Isabel J. Sible, Anisa Marshall, Fatemah Shenasa, Aimée Gaubert, David Robert Bradford, Lorena Sordo, Xingfeng Shao, Kathleen Rodgers, Elizabeth Head, Danny Jj Wang and Daniel A. Nation, 9 January 2025, Neurology.
DOI: 10.1212/WNL.0000000000210210

The research was supported by National Institutes of Health grants R01AG064228, R01AG060049, R01AG082073, P01AG052350, P30AG066530, and a grant from the American Heart Association, 23PRE1014192.

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