Blood Vessel Dysfunction in Temporal Lobes Linked to Mild Cognitive Impairment in Adults

A new USC-led study suggests that microvascular trouble may be an important, early biomarker for dementia as well as a potential target for therapy. The findings, seen in people with and without signs of amyloid buildup in the brain, involved scientists from multiple universities and appears 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-related brain changes. They still had this blood vessel problem if they had memory issues.”

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.

During the 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 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.”

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