Fw: NATAP: Exercise & Cognitive Function/Brain Aging

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Exercise May Prevent Loss of Small Blood Vessels in the Brain

By a Fiore, Staff Writer, MedPage Today

Published: December 01, 2008

Reviewed by Zalman S. Agus, MD; Emeritus Professor

University of Pennsylvania School of Medicine.

CHICAGO, Dec. 1 -- Older adults who exercise regularly may have increased cerebral blood flow and a greater number of small blood vessels in the brain, researchers here said.

This could be the mechanism by which exercise prevents cognitive decline in the elderly, Feraz Rahman, M.S., a medical student at Jefferson Medical College in Philadelphia, told attendees at the Radiological Society of North America meeting.

"Aerobic exercise improves cognitive function … and counteracts the effects of aging on the brain," Rahman said. "That may be due to blood flow and vasculature."

Action Points  

    * Explain to interested patients that exercise may prevent the loss of small blood vessels in the brain, which may have a protective cognitive effect.

    * Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Previous research has shown that exercise reverses small vessel disease elsewhere in the body, and increases brain volume and cognitive function in the elderly.

So Rahman and his colleagues theorized that blood vessel and flow differences may be one explanation by which exercise has this beneficial effect.

To assess small vessel loss and its relationship to cerebral blood flow, the researchers conducted a cross-sectional retrospective study of 12 adults, ages 60 to 80, six of whom had exercised three hours a week or more over the past 10 years. The others exercised fewer than 1.5 hours a week over the same time period.

The researchers performed brain scans of the two groups, using MRI to determine cerebral blood flow and MR angiography to locate blood vessels.

They then used a 3-D computer reconstruction method to model blood vessels, calculating the radius of each vessel and the average blood flow to different regions of the brain.

The active group had significantly more smaller vessels (<0.35 mm) than the inactive group (P<0.05).

Active patients also had better cerebral blood flow, Rahman said, compared with the inactive group, which had more unpredictable blood flow (P<0.01).

The researchers observed a correlation between vessel radius and blood flow. For active adults, as blood vessel radius increased, blood flow increased. But for inactive adults, as vessel radius increased, blood flow decreased.

"These findings could be explained by greater small vessel loss in the inactive group," the researchers said. "With fewer small vessels, the average vessel ratio in a given vascular tree increases along with vascular resistance leading to decreased cerebral blood flow."

Rahman noted that the study was small because, although they screened 120 patients, they could not find enough of those who were healthy enough to participate.

Future studies need to be done to examine whether exercise in an inactive group would improve blood flow and vasculature, he said.

ph Tashjian, M.D., of the University of Minnesota in Minneapolis, who moderated the session at which the study was presented, said it would be beneficial to conduct a longitudinal study in this population to assess the effects of exercise on cognitive outcomes.

"This population was relatively young, so cognitive impairment might not show up for five to 10 years," Dr. Tashjian said. "We will want to see if the ones who exercise will have less cognitive impairment compared with those who don't."

Rahman concluded that the findings of this study show that "exercise is a vital part of healthy aging and might slow the loss of small vessels."

The study was funded by the UNC Biomedical Research Imaging Center and by a grant from the NIH.

The authors reported no disclosures.

Primary source: RSNA Meeting 2008

Source reference:

Rahman FN, et al "Relationship of exercise to cerebral vasculature and blood flow in older adults" RSNA 2008; Abstract LL-NR2256-D03.