Mild cognitive impairment is linked to the dysfunction of blood vessels in the brain’s temporal lobes – the seat of memory – according to a new USC-led study.
The findings, observed in people with and without signs of amyloid buildup in the brain, suggest that microvascular problems may be an important, early biomarker for dementia, as well as a potential target for therapy.
The research, which involves scientists from several universities, appears in the journal Neurology.
We study the ability of these very small blood vessels to respond to stimuli and dilate, and they show dysfunction in people with memory problems. It may imply blood vessel dysfunction in the very early stages of memory loss. It happened regardless of whether or not people had Alzheimer’s disease-related brain changes. They still had this blood vessel problem when they had memory problems.”
Daniel Nation, senior author, professor of gerontology and medicine at the USC Leonard Davis School of Gerontology
New biomarker for dementia
For the study, researchers recruited a sample of 144 older, community-dwelling adults from the community. The volunteers underwent a neuropsychological examination, gave blood samples and underwent a brain MRI, or magnetic resonance imaging.
During MRI, volunteers held their breath for 15 seconds, an exercise designed to dilate the brain’s blood vessels, a natural process called “cerebrovascular reactivity” that regulates oxygen levels in the brain.
Researchers paid special attention to the blood vessels that supply the temporal lobes, located on the sides of the head, near the ears. Participants whose blood vessels did not dilate properly showed signs of cognitive impairment.
“With this approach, we can pinpoint the problem with 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 is an increasing realization that the main cause of dementia is not actually Alzheimer’s disease, but mixed pathology. If you just focus on amyloid you certainly don’t get the full picture. Perhaps this technique should be incorporated into our diagnostic approaches included. .”
“Our findings underscore the need to focus on vascular health as a critical factor in memory loss,” said first author Arunima Kapoor, a graduate student at the University of California, Irvine.
Nation said some blood pressure medications may be able to protect vascular function in a way that preserves memory, but more research is needed.
About this study
In addition to Nation and Kapoor, participants include John Paul Alitin, Trevor Lohman, Isabel Sible, Anisa Marshall, Aimee Gaubert, Xingfeng Shao and Danny Wang, all from USC; Shubir Dutt of the University of California, San Francisco; Allison Engstrom and Fatemah Shenasa, Lorena Sordo and Elizabeth Head, all from University of California, Irvine; and David Robert Bradford and Kathleen Rodgers of the University of Arizona.
The research was supported by grants from the National Institutes of Health R01AG064228, R01AG060049, R01AG082073, P01AG052350, P30AG066530, and an American Heart Association grant, 23PRE1014192.
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Magazine reference:
Kapoor, A., et al. (2025). Association of medial temporal lobe cerebrovascular reactivity and memory function in older adults with and without cognitive impairment. Neurology. doi.org/10.1212/wnl.0000000000210210.