Aerobic Exercise Boosts Cognition, Even in Very Young Adults

Michael Vlessides

February 06, 2019

Regular aerobic exercise including walking, cycling, or climbing stairs may improve cognition, particularly executive function, in both in older adults as well as their young counterparts new research shows.

Results of the study showed those who performed aerobic exercise had significantly improved mean executive-function test scores (mean 0.50-point improvement) than those who did stretching and toning (mean 0.25-point improvement).

"Aerobic exercise was beneficial for cognition, and the main domain that benefitted was executive function," study investigator Yaakov Stern, PhD, of the Columbia University College of Physicians and Surgeons, New York City, told Medscape Medical News.

"The interesting thing is that we found aerobic exercise also benefits younger people, both in terms of cognition as well as cortical thickness, which has never been shown before," Stern added.

The study was published online January 30 in Neurology.

Elderly-Only Research

Previous research has shown the cognitive benefits of aerobic exercise in animals and humans alike, particularly with respect to attention, processing speed, executive function, memory, and working memory. These studies have also linked aerobic exercise to increased gray matter volume/cortical thickness, particularly in the frontal, temporal, and cingulate cortex.

Despite such promising findings, controlled exercise studies in humans have largely been restricted to the elderly, leading the current team of investigators to hypothesize that early exercise interventions may delay or even prevent age-related changes in younger people. In addition, younger people may derive different types of cognitive benefits from aerobic exercise than their older counterparts.

"It would make sense that exercise should improve cognition in younger people, but we hadn't seen a controlled trial that tested it," said Stern.

In the randomized, parallel-group, observer-masked, community-based clinical trial, All eligible participants underwent baseline fitness testing. The study included 132 adults with below-average aerobic capacity. Individuals who experienced ischemic changes, abnormal blood pressure responses, or significant ectopy were excluded. No participant smoked or had dementia.

Participants were randomly assigned to one of two groups. Individuals in each group underwent four weekly training sessions over 6 months. All training was performed at a fitness center, and participants had weekly check-ins with coaches to monitor their progress. The two groups were comparable with respect to age, sex, and education, as well as baseline memory and cognitive skills.

Individuals in the exercise group chose from a variety of aerobic activities, including walking on a treadmill, cycling using a stationary bike, or using an elliptical machine. Those in the stretching/toning group did exercises to promote flexibility and core strength. Participants in both groups underwent 10-15 minutes of warm-up/cool down and 30-40 minutes of workout.

Cognitive function in several domains, including executive function, episodic memory, processing speed, language, and attention, along with everyday function and body mass index (BMI), were evaluated at study initiation, 3 months and 6 months. Participants also underwent MRI brain scans at the start and end of the investigation to determine cortical thickness.

The study showed that aerobic capacity significantly increased (β = 2.718; P = .003) and BMI significantly decreased (β = −0.596; P = .013) in the aerobic exercise group, but not in the stretching and toning group.

Available to Most People

Aerobic exercise also improved cognition. Indeed, over the 6-month study period, individuals who performed aerobic exercise had a mean increase in executive function test scores of 0.50 ± 0.08 standard-deviation (SD) units, significantly better than those who did stretching and toning (0.25 ± 0.11 SD-unit increase).

The effects of exercise on cognitive skills also seemed to improve with age. Among 40 year olds, the improvement in cognitive skills was 0.228 SD units greater (95% CI, 0.007 - 0.448) in those who exercised. By age 60, it was 0.596 SD units greater (95% CI, 0.219 - 0.973) in the aerobic exercisers.

The researchers also collected data on APOE ε4 genotype in a subset of 90 participants. After controlling for age and baseline performance, this analysis showed that individuals with at least one APOE ε4 allele had less improvement in executive function with aerobic exercise than their counterparts who performed aerobic exercise but did not have the marker (β = 0.5129; 95% CI, 0.0381 - 0.988; P = .0346).

Interestingly, MRI scans revealed that patients in the aerobic exercise group experienced significantly increased cortical thickness in the left caudal middle frontal cortex Brodmann area, and there was no interaction with these findings and age. Nevertheless, no correlation was found between change in cortical thickness and change in any cognitive domain.

Despite the promising link between exercise and cognition, investigators did not find an association between exercise and improved memory.

Stern noted that the organic nature of the study also helps demonstrate that the cognitive benefits of aerobic exercise are available to most people.

"We performed the study in conjunction with a series of [YMCAs] across Manhattan," he said. "So participants — who were not exercisers to begin with — could just go to whichever one they wanted and exercise on their own at the gym.

"Of course we monitored them carefully and called them regularly to encourage them to comply, but it speaks to something more granular when people are going to the gym and getting on whatever machine they want and doing it on their own time as opposed to having fixed appointments in a lab," he added.  

Feasible, Effective Intervention

Commenting on the findings for Medscape Medical News, Steven T. DeKosky, MD, the Aerts-Cosper Professor of Alzheimer's Research at the University of Florida College of Medicine and a Fellow of the American Academy of Neurology, said the study is of great interest given the broad age range of its participants, as well as the lack of effect of age on observed improvements.

"There is a good deal of research in animals which shows that exercise improves physical and cognitive performance; such studies have allowed development of hypotheses that have been at least partly confirmed in man — for example, that growth factors are elevated in both mice and men with exercise," said DeKosky, who was not involved in the research.

"This study enables further work in the area, allowing a mechanistic and potentially therapeutic intervention," he said.

DeKosky also liked the study's inclusion of participants who were below the median with respect to physical performance.

"That the benefits were shown in the (somewhat) couch-bound population should be a further stimulus to these kinds of activities for maintenance of health in general, and that comes with cognitive benefits as well," he added.

Stern concluded that the study's findings have significant implications for public health, and open the door to a feasible, flexible intervention that addresses cognitive/brain health for adults of all ages.

"It's more and more recognized that exercise is important for health," he concluded. "And I think this study really reinforces that, and now extends those benefits to younger people."

The study was supported by the National Institutes of Health. Stern and DeKosky have reported no relevant financial relationships.

Neurology. Published online January 30, 2019. Abstract

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