War Shrinks Brains
Until recently, most neuroscientists accepted as dogma the idea that neurogenesis does not occur in adults. But we know that cells in adult brains do divide, making neurons in the process. The new neurons are located in the parts of the brain most important for processing recently learned information and for laying down memories — the hippocampus and the prefrontal cortex.
Sufferers of combat stress — “posttraumatic stress disorder” — have smaller hippocampi than normal, and the shrinkage increases with the length of combat exposure. Stress increases the level of corstisol in the brain, and cortisol is probably responsible for the shrinkage of the hippocampus. Patients with Cushing’s syndrome, in which too much cortisol is produced, also have smaller hippocampi. Stress is bad for the brain — except the particular brand of stress brought on by exercise.
Exercise protects the brain from sources of both physical and nonphysical stress. Feeling depressed? Exercise. Stressed out? Exercise!