Previous studies have shown that aerobic exercise benefits cognitive functioning in older people, but new research suggests that different forms of regular aerobic exercise can also improve cognitive processes in people as young as 20 years of age. The studies, headed by a team at Columbia University, also found that the level of positive effects of exercise on thinking skills such as executive function, increased with increasing age. Executive function is a set of thinking skills that we use in our everyday lives, and includes our ability to regulate our own behavior, pay attention, organize, and achieve goals.

“As people age, there can be a decline in thinking skills, however, our study shows that getting regular exercise may help slow or even prevent such decline,” commented Yaakov Stern, PhD, chief of cognitive neuroscience in the department of neurology, Columbia University, a faculty member at the Taub Institute, and lead author of the team’s published paper in Neurology, the medical journal of the American Academy of Neurology. “We found that all participants who exercised not only showed improvements in executive function but also increased the thickness in an area of the outer layer of their brain.”

The Columbia University team and colleagues at Nathan Kline Institute for Psychiatric Research, New York State Psychiatric Institute, and Columbia Presbyterian Medical Centre, reported their findings in a paper titled, “Effect of aerobic exercise on cognition in younger adults.”

Most studies evaluating the effects of controlled aerobic exercise on cognition have focused on adults aged 55 years or older, and have reported benefits in areas including attention processing speed, executive function, memory, and working memory, the authors explained. To broaden the scope of the study and evaluate the effects aerobic exercise on different aspects of cognitive function in much younger individuals Stern and co-lead Richard P. Sloan, PhD, the Nathaniel Wharton professor of behavioral medicine in the department of psychiatry, headed a randomized, controlled trial in participants aged 20–67 years.

“We hypothesized that aerobic exercise would have cognitive benefits even in this younger age range, but that age might moderate the nature or degree of the benefit,” the researchers explained. The trial included 132 adults in the 20–67 years age range, who were all below median aerobic capacity at the start of the study. The participants were then randomized to undertake either an aerobic exercise training program over 6 months, or a 6-month control program of stretching and core-strengthening exercises.

Both exercise groups worked out 4 times per week with trained coaches at a fitness center. The aerobic exercise participants were given the freedom to choose their preferred form of effective workout, which included walking on a treadmill, cycling on a stationary bike, or using an elliptical trainer. The aerobic exercise subjects all wore heart rate monitors, and worked up to training at 75% of their maximum heart rate. The control group undertook a program of stretching and toning that targeted flexibility and core strength.

Participants were all tested for cognitive parameters including executive function, processing speed, language, attention, and episodic memory, before the exercise programs were initiated, and then at 12 weeks and at 24 weeks. They also underwent MRI brain scans to look for any changes in brain structure. Ninety-four of the 132 subjects completed the full 6-month program.

The results showed that aerobic exercise was linked with increased executive function thinking skills across all the age ranges, when compared with test scores in the control group. By the end of the 6-month intervention, individuals who did aerobic exercise increased their executive function test scores by 0.5 points, which was statistically significant when compared with the 0.25-point improvement shown by the stretching and toning group. At 40 years of age, the improvement in thinking skills was 0.28 standard deviation units higher among those who did aerobic exercise, compared with those who did stretching and toning. At age 60 years, the difference was 0.596 standard deviation units higher, the researchers reported.

“Since a difference of 0.5 standard deviations is equivalent to 20 years of age-related difference in performance on these tests, the people who exercised were testing as if they were about 10 years younger at age 40 and about 20 years younger at age 60,” said Stern, who is also professor of neuropsychology in the departments of neurology and psychiatry and a member of the Gertrude H. Sergievsky Center and the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University Irving Medical Center.

“Exercise function usually peaks at around 30 years of age, he noted. “Since thinking skills at the start of the study were poorer for participants who were older, our findings suggest that aerobic exercise is more likely to improve age-related declines in thinking skills rather than improve performance in those without a decline.”

In contrast, there was no evidence that aerobic exercise improved cognitive parameters including processing speed, language, attention, or episodic memory at any age, possibly due to the small size of the study population, the authors pointed out. Prior studies have found that exercise can benefit these areas of cognition in the over-55s, and Stern said that a larger trial may have enough power to detect such changes in younger adults, or it may be that exercise affects younger and older people differently.

“Limitations of this study include its relatively small sample size, which reduces power to see significant effects,” the researchers acknowledged. “It is possible that we would have been able to see effects in other cognitive domains with a larger sample size. It will be important for future studies to assess the sustainability of exercise effects over periods of time beyond the duration of the trial.”

Interestingly, brain imaging at the start of the study and at week 24 suggested that aerobic exercise training was also associated with structural changes in particular regions of the brain. “We also demonstrated that aerobic exercise was associated with increased cortical thickness in the left caudal middle frontal area,” the authors wrote. “This effect did not differ by age, and extends an observation typically noted in older adults to a younger age range …Thus, our findings suggest that exercise may improve brain health across ages 20–67.”

The finding that the benefits of aerobic exercise extend to much younger individuals than has been demonstrated in previous studies could be important from a public health perspective, the team concluded. “These findings have strong public health implications and allow the recommendation of a feasible, flexible intervention for cognitive and brain health for adults of all ages.”

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