Watch: Episode 9: Can exercise make you smarter? Scientists think it’s possible

When you exercise, your muscles release molecules that can ultimately get into your brain. Once inside, studies have shown, they can stimulate the brain to grow new neurons. Which raises a tantalizing question: Can exercise make you smarter?

There are some hints that the answer may be yes. People with early signs of dementia can benefit from physical activity, for instance. Yet despite such preliminary findings, the full effects of exercise on the brain remain mysterious.

Wendy Suzuki, a psychologist at New York University, is now trying to fix that. She runs a lab where she can carefully measure the effect. Suzuki has volunteers run on a treadmill in her lab while she measures their oxygen consumption. Then she gives her subjects a battery of psychological tests to measure things like their memory and attention.

Suzuki has found that healthy people can improve their cognition with exercise right away. She has also found that people with brain injuries experience significant improvement in their mood. Now she’s running a class in which her students exercise at a gym three times a week, to see how their brains change over a full semester.

Ultimately, Suzuki hopes to come up with an optimal plan to help cognition at every age. Just walking won’t be enough, she warned; it may involve several days a week of moderate exercise. “My answer’s not going to be you have to become a triathlete to get these brain effects,” she assured me. “It’s not going to be so over the top.”