BDNF is brain-derived neurotrophic factor. In Spark: The Revolutionary New Science of Exercise and the Brain by John Ratey, he calls it Miracle-Gro in the brain. It’s the material that makes the synapses grow and prosper due to brain activity.

Exercise elevates the production of BDNF throughout the brain. One of the early researchers to study this was Dr. Carl Cotman, director of the Institute for Brain Aging and Dementia at the University of California, Irvine. Cotman’s work with mice showed increased levels of BDNF in the hippocampus as a direct result of exercise. The farther the mice ran, the higher the levels of BDNF. Remember what we said earlier: the hippocampus is one of the areas of the brain most affected in the early stages of Alzheimer’s.

Cotman said, “One of the prominent features of exercise, which is sometimes not appreciated in studies, is an improvement in the rate of learning. It suggests that if you’re in good shape you may be able to learn and function more efficiently.”

Art Kramer added: “There are actually several of these neurotrophins that have been associated with increased exercise. In addition to BDNF, insulin-like growth factor-1 and vascular endothelial growth factor are increased with exercise.”