Exercise and cognitive health

By Dan Peterson

One of the most interesting recent findings in neuroscientific research–and one that might not seem intuitive at first blush–is the tremendous strength of the link between exercise, learning and overall cognitive health. The emerging understanding of the connection between exercise and cognitive health is further confirmation of the larger idea, echoed in recent research around our anatomy and the biomechanics of human movement, that we human beings were designed to move and be athletic.

Exercise has been linked to a diverse array of positive effects on our cognitive and emotional health, including lower levels of depression and anxiety and an improved ability to deal with psychological stress. The mechanism behind exercise’s ability to modulate mood and anxiety is rooted in the way that it regulates levels of neurotransmitters in the brain. But exercise also has a powerful effect on learning, and it is hypothesized that this effect is achieved via the surge in BDNF (brain-derived neurotrophic factor) set off by exercise.

BDNF is integral in the processes of neural plasticity–changes in the brain resulting from interacting with our environment. Dr. John Ratey, a psychiatrist on faculty at Harvard Medical School, has a great description of BDNF and its importance in his book on exercise and the brain, Spark:

A neuron is like a tree that instead of leaves has synapses along its dendritic branches; eventually new branches sprout, providing more synapses to further solidify the connections. These changes are a form of cellular adaptation called synaptic plasticity, which is where BDNF takes center stage.

Early on, researchers found that if they sprinkled BDNF onto neurons in a petri dish, the cells automatically sprouted new branches, producing the same structural growth required for learning–and causing me to think of BDNF as Miracle-Gro for the brain.

And the link between BDNF and exercise is a strong one. In a study conducted by Carl Cotman at Columbia University, mice were divided into four groups that ran for zero, two, four or seven nights, and were then injected with a molecule that binds to BDNF so that levels of the protein could be measured. Not only did the mice that exercised show higher levels of BDNF, but there was a direct relationship between the amount of running that the mice did and BDNF levels in their brains. What’s more, elevated levels of BDNF were not just found in areas of the brain associated with movement, which one might expect given that the mice were exercising, but in the hippocampus as well, a brain area strongly associated with learning and new memory formation.

So the evidence of a link between exercise and BDNF, a protein that promotes synaptic growth and neural plasticity is a strong one. But the intriguing question then becomes, why are exercise and learning linked? According to Ratey, this linkage arises out of the primal connection between movement and survival:

[This] makes perfect sense in light of evolution. If we strip everything else away, the reason we need an ability to learn is to help us find and obtain and store food. We need fuel to learn and we need learning to find a source of fuel–and all these messengers from the body keep this process going and keep us adapting and surviving….

…Learning and memory evolved in concert with the motor functions that alllowed our ancestors to track down food, so as far as our brains are concerned, if we’re not moving, there’s no real need to learn anything.

And this connection is not purely theoretical. In a 2007 German study, researchers had participants go through bouts of intense exercise, which was then followed by a vocabulary learning task. Results showed the predicted spike in BDNF levels in the exercise group, but also that the exercise group learned new vocabulary 20 percent faster than the control group.

At a competitive level, this research could be powerful in guiding the structure of practices, and when teaching and coaching will be most effective. Rather than beginning practice with a lecture or a film session, these sessions might be more effective after athletes spend some time working out and pumping blood through the brain.

On a broader level, this research underscores just how important exercise is to overall health. Not only is it a cornerstone of physical health and fitness. But it is rapidly becoming accepted that regular exercise makes us smarter, helps us learn faster and has a positive effect on mood and emotional regulation as well. It is yet another blow to traditional ideas about the separation mind and body.

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