Researchers studied two elderly populations that had led different lifestyles, one sedentary and one active. Cognitive scores were profoundly influenced. Exercise positively affected executive function, spatial tasks, reaction times and quantitative skills. So researchers asked: If the sedentary populations become active, will their cognitive scores go up? Yes, it turns out, if the exercise is aerobic. In four months, executive functions vastly improve; longer, and memory scores improve as well. Exercise improves cognition for two reasons: Exercise increases oxygen flow into the brain, which reduces brain-bound free radicals. One of the most interesting findings of the past few decades is that an increase in oxygen is always accompanied by an uptick in mental sharpness. Exercise acts directly on the molecular machinery of the brain itself. It increases neurons’ creation, survival, and resistance to damage and stress.