Young adults who do cardio could have better thinking skills in their 40s and 50s.

"Many studies show the benefits to the brain of good heart health," study author David R. Jacobs, Jr, PhD, with the University of Minnesota in Minneapolis, said in an American Academy of Neurology news release reported. "This is one more important study that should remind young adults of the brain health benefits of cardio fitness activities such as running, swimming, biking or cardio fitness classes."

A research team looked at 2,747 healthy people with an average age of 25. The participants were asked to take a treadmill test, and then participated in the same test 20 years later.  A cognitive test was also given 25 years after the beginning of the study that tested "verbal memory, psychomotor speed (the relationship between thinking skills and physical movement) and executive function," the news release reported.

In the treadmill test the participants walked or ran as the "speed and incline increased" until they were physically unable to continue or had shortness of breath. In the first test when the participants were in their 20s they lasted for an average time of 10 minutes; 20 years later that number had decreased by 2.9 minutes.

The team found that for every additional minute the participants were able to stay on the treadmill they were able to recall 0.12 more words correctly on a 15 word memory test.  They also "correctly replaced 0.92 more numbers with meaningless symbols in the test of psychomotor speed 25 years later, even after adjusting for other factors such as smoking, diabetes and high cholesterol," the news release reported.

"These changes were significant, and while they may be modest, they were larger than the effect from one year of aging," Jacobs said. "Other studies in older individuals have shown that these tests are among the strongest predictors of developing dementia in the future. One study showed that every additional word remembered on the memory test was associated with an 18-percent decrease in the risk of developing dementia after 10 years."

People whose time on the treadmill decreased minimally over the two decades were more likely to perform well on executive function tests than those who had more dramatic decreases.

"These findings are likely to help us earlier identify and consequently prevent or treat those at high risk of developing dementia," Jacobs said.