In a new study led by scientists from the University of Texas Southwestern Medical Center, aerobic exercise training reduced central arterial stiffness and increased cerebral blood flow in patients with mild cognitive impairment, an early stage of Alzheimer’s disease.
As many as one-fifth of people age 65 and older have some level of mild cognitive impairment — slight changes to the brain that affect memory, decision-making, or reasoning skills.
Scientists have previously shown that lower-than-usual levels of blood flow to the brain, and stiffer blood vessels leading to the brain, are associated with mild cognitive impairment and dementia.
Studies have also suggested that regular aerobic exercise may help improve cognition and memory in healthy older adults.
However, they have not established whether there is a direct link between exercise, stiffer blood vessels, and brain blood flow.
“This is part of a growing body of evidence linking exercise with brain health,” said Professor Rong Zhang, a researcher in the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, the Department of Neurology at the University of Texas Southwestern Medical Center, and the Internal Medicine University of Texas Southwestern Medical Center.
“We’ve shown for the first time in a randomized trial in these older adults that exercise gets more blood flowing to your brain.”
“There is still a lot we don’t know about the effects of exercise on cognitive decline later in life,” said Professor C. Munro Cullum, a researcher in the Department of Neurology and the Department of Psychiatry at the University of Texas Southwestern Medical Center.
“Mild cognitive impairment and dementia are likely to be influenced by a complex interplay of many factors, and we think that, at least for some people, exercise is one of those factors.”
The study involved 70 men and women (aged 55 to 80) diagnosed with mild cognitive impairment.
Participants underwent cognitive exams, fitness tests, and brain magnetic resonance imaging (MRI) scans.
Then they were randomly assigned to either follow a moderate aerobic exercise program or a stretching program for one year.
The exercise program involved 3-5 exercise sessions a week, each with 30-40 minutes of moderate exercise such as a brisk walk.
In both programs, exercise physiologists supervised participants for the first four to six weeks, then had the patients record their exercises and wear a heart rate monitor during exercise.
Forty-eight study participants (29 in the stretching group and 19 in the aerobic exercise group) completed the full year of training and returned for follow-up tests.
Among them, those who performed aerobic exercise showed decreased stiffness of blood vessels in their neck and increased overall blood flow to the brain.
The more their oxygen consumption (one marker of aerobic fitness) increased, the greater the changes to the blood vessel stiffness and brain blood flow.
Changes in these measurements were not found among people who followed the stretching program.
“While the study didn’t find any significant changes in memory or other cognitive function, this may be because of the small size or short length of the trial,” the researchers said.
“Changes to blood flow could precede changes to cognition.”
The findings were published in the Journal of Alzheimer’s Disease.
Tsubasa Tomoto et al. 2021. One-Year Aerobic Exercise Reduced Carotid Arterial Stiffness and Increased Cerebral Blood Flow in Amnestic Mild Cognitive Impairment. Journal of Alzheimer’s Disease 80 (2): 841-853; doi: 10.3233/JAD-201456
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