New study shows that exercise boosts blood flow to the brain: could be the key to preventing dementia

When you regularly work out at the gym—or take frequent walks to the park— it’s not only your limbs and heart that get a good kick out of it. Turns out your brain experiences a massive boost too! In fact, a new study conducted by researchers from UT Southwestern has shown that older adults suffering from mild memory loss will experience increased blood flow to the brain if they follow an exercise program for at least one year. The results of the study were published in the online journal, Alzheimer’s Disease.  According to lead researcher and professor of neurology at UTSW, Rong Zhang, these conclusive findings add to a growing body of evidence that strongly links exercise with brain health. And now for the first time in medical history, trials conducted in older adults have confirmed that exercising does increase blood to flow to your brain.  Results such as these are groundbreaking to the medical fraternity because at least one-fifth of the world population—aged 65 and older—have some sort of mild cognitive impairment (MCI). These impairments lead to slight changes in the brain that affect decision-making, cognitive skills, reasoning skills, and memory. In extreme cases, mild cognitive impairment progresses to dementia, and potentially Alzheimer’s disease.  Previously, scientists were able to demonstrate that low levels of blood flow to the brain led to stiffer blood vessels; a feature strongly linked to mild cognitive impairment and dementia. These studies also showed that the inclusion of consistent aerobic exercise could significantly improve memory and cognition in healthy aging adults.  The problem is that scientists are yet to identify a direct link between exercising, stiffer blood vessels, and blood flow to the brain. 

“There is still a lot we don’t know about the effects of exercise on cognitive decline later in life. MCI 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,” says C. Munro Cullum—Ph.D., professor of psychiatry at UTSW and co-senior author of the study. 

During the study, the research team led by Dr. Zhang analyzed 70 men and women aged between 55 and 80 who had been diagnosed with Mild Cognitive Impairment. Participants undertook a series of fitness tests, cognitive exams, and brain magnetic resonance imaging (MRI) scans. They were then randomly assigned to either follow a one-year stretching program or a moderate aerobic exercise program for the same duration. The exercise program consisted of three to five exercise sessions a week; then followed up by 30-40 minutes of moderate exercises, such as taking a stroll or a light jog. In each of the respective programs, the participants were assigned to exercise physiologists that supervised them for the first four to six weeks. They were required to have a heart rate monitor during their sessions.  Out of the 140 participants that participated in the study, 19 participants from the aerobic exercise group and 29 from the stretching group managed to complete a full year of training as well as return for follow-up tests. Those who completed the aerobic exercise program showed a decreased stiffness of blood vessels in their neck and a marked improvement of blood flow to the brain.  Participants who had higher levels of oxygen consumption—one distinctive marker of aerobic fitness—had significant changes to brain blood blow and blood-vessel stiffness. Interestingly, these measurements were not recorded in the participants who completed the stretching program.  On the other hand, the study did not record any significant changes to cognitive function and memory. But the research team strongly believes that this could be due to the short duration of the study. Perhaps changes to blood flow could take place first, then gradual changes to cognition.  That being said, the research team is currently carrying out a two-year study on Risk Reduction for Alzheimer’s Disease; with the aim of discovering a link between exercise and cognitive decline.  While it’s natural that some people benefit more from exercise than others, the data collected from this study will be beneficial in explaining the effects of exercise on the brain. 

“Having physiological findings like this can also be useful for physicians when they talk to their patients about the benefits of exercise. We now know, based on a randomized, controlled trial, that exercise can increase blood flow to the brain, which is a good thing,” says Zhang.