Exercise is good for the brain, but improving its blood vessels may take more time

People with less stable patterns of blood flow in the brain may be at greater risk of dementia and cerebrovascular disease. To study whether regular aerobic exercise might help, researchers at Iowa State University conducted a pilot study, the results of which were recently published in the Journal of Applied Physiology.

"The main takeaway is that exercise is good for the arteries and the brain, but the effects are complex and take time to accumulate," said Wes Leffers, lead author and associate professor of kinesiology.

Leffers studies the stiffness of large arteries and blood flow to the brain in middle-aged people and how this affects heart and brain health in later life.

He said participants in the exercise group in the pilot study showed improvements in cognitive function and peak VO2 — a measure of aerobic fitness and the body’s ability to use oxygen during exercise. But to the researchers’ surprise, cerebral blood flow instability increased among the exercise group. While it wasn’t statistically significant, Leffers noted that the finding is consistent with other recent studies.

"It may be that the brain's vascular system takes longer to adapt to training compared to the heart and central vessels like the aorta," Leffers added, noting that other studies with a year of training have shown improvements in continuous blood flow to the brain.

Additional information about the pilot study The pilot study at Iowa State University included 28 participants aged 40 to 64 years. All were considered inactive and had high blood pressure, or stage 1 hypertension.

Nineteen people were randomly assigned to 12-week aerobic exercise programs three times a week. Participants wore heart rate monitors synchronized with their exercise machines, which automatically adjusted speed, incline, or resistance to keep their heart rate in a predetermined range for that session.

Participants, including those who did not exercise, were asked to maintain their normal physical and dietary lifestyles.

The researchers measured blood flow pulsations using noninvasive Doppler ultrasound and tonometry, which measures pressure inside the eyes, at the beginning, middle, and end of the pilot study. Cardiorespiratory fitness and cognitive measures from three tests were collected at the beginning and end of the study.

Leffers noted that the tasks focused on "memory and executive function, which are most strongly impacted by aging and cognitive disease."

Specific results Peak VO2 increased by 6% in the aerobic training group and decreased by 4% in the control group. Cerebral blood flow pulsatility tended to increase in the aerobic training group. Working memory response improved with aerobic training but not in the control group. Marian Kohut, the Barbara E. Forker Professor of Kinesiology; Angelique Brellenthin, assistant professor of kinesiology; graduate students Krista Reed and Quinn Keleher; and undergraduate student Abby Freskoln co-authored the paper.

Leffers said the research team is interested in repeating and expanding the pilot study, but with a focus on women going through menopause.

"There is evidence that the vascular benefits of exercise decline after menopause, but we don't know what happens to the cerebral vasculature and potential brain benefits," Leffers said.

By understanding the effects and limitations of exercise and the underlying vascular mechanisms of dementia and cerebrovascular disease, researchers hope to shed light on behavioral interventions that may improve health and quality of life.