Regular exercise can combat a host of age-related cognitive declines, scientists are finding. But a new study indicates that exercise benefits not only older brains but also those of young adults. The research suggests that frequent exercise helps young adults to suppress inhibitions, a skill critical during complex tasks such as driving, and that it works by improving blood flow to the brain.
“I had been noticing over the years that university students appeared progressively less fit, and I wondered whether we might find significant relationships between exercise levels, blood flow in the brain, and cognition in the young adults,” says Liana Machado of the University of Otago in New Zealand. Scientists had found such relationships in older adults and clinical populations, but “no studies to date have considered them in healthy young adults.”
Machado and her colleagues used a multi-pronged approach to study these relationships. First, unlike past studies, they measured both aerobic fitness levels and self-reported exercise frequency in 18 to 30-year-olds. They also asked the participants to engage in a series of cognitive tasks that progressed from simple motor tasks through to complex tasks that depended on higher levels of strategic control. Finally, they assessed the participants’ cerebrovascular systems – how blood flow to the brain responded to changing carbon dioxide levels.
The researchers were surprised by what they found: a significant link between exercise frequency and superior control over reflexive responses. “Originally, the young adults were intended as more of a control group than an experimental group,” Machado says. “Given that healthy young adults are in their prime in terms of cognitive and neural development, we did not expect this group to be very sensitive to engagement in physical activity.” Also surprising, she says, was that the experiment with young adults pointed to a potential mediator of this relationship – efficacy of brain blood-flow regulation.
The types of tasks that benefited from frequent exercise, the researchers found, were those that depend on the suppression of reflexive responses. For example, when we drive, we must strike a balance between responding to changes in our visual environment while responding strategically to internal goals of where to go and how.
This work comes at a time of increased scientific focus on the link between exercise and cognitive health in the elderly. A recent paper in Neurology by Alan Gow and colleagues at the University of Edinburgh in Scotland, for example, indicated that exercise is a powerful factor in combating brain shrinkage among aging adults. Machado’s team extends the exercise-cognition link to young people while offering a possible mechanism for the link for all age groups. “More research is clearly needed before this question can be answered,” she says. “However, it may turn out to be the case that superior cerebrovascular function afforded by regular engagement in exercise promotes neuronal health and longevity, thereby lessening age- and disease-related brain shrinkage.”
Importantly, the work suggests that frequency, as opposed to intensity, of exercise may be key to cognitive health. “More frequent exercise may be best, so why not take the stairs instead of the elevator and walk to lunch instead of driving,” Machado says. The researchers also found that body mass index was not a key factor, indicating that regular engagement in physical activity may be more important than body weight. “I think the idea that young people do not have to worry about exercising since they are in their prime developmentally is rapidly being overturned by mounting evidence that even the brains of young adults can benefit from regular engagement in exercise,” she says.
The research team plans to look next at the role of the cerebrovascular system in older adults, including examining brain blood flow responses to changes in blood pressure. In the long-term, Machado also is interested in studying how diet influences cognitive health and cerebrovascular function.
-Lisa M.P. Munoz
The research received the Richard Kammann Memorial Prize in Applied Psychology, and a review article by Hayley Guiney and Machado entitled “Benefits of Regular Aerobic Exercise for Executive Functioning in Healthy Populations” is in-press at Psychonomic Bulletin & Review.
Media contact: Lisa M.P. Munoz, CNS Public Information Officer,