Aerobic exercise -- any exercise that gets the heart pumping -- may reduce the risk of dementia and slow its progression once it starts, U.S. researchers say. Dr. J. Eric Ahlskog, a neurologist at Mayo Clinic in Rochester, Minn., and colleagues examined the scientific literature on the subject of exercise and cognition, including animal studies and observational studies, that included more than 1,600 papers, with 130 used in the review. \"We concluded that you can make a very compelling argument for exercise as a disease-modifying strategy to prevent dementia and mild cognitive impairment, and for favorably modifying these processes once they have developed,\" Ahlskog says in a statement. Brain imaging studies have consistently revealed objective evidence of favorable effects of exercise on human brain integrity, while animal research showed exercise generates trophic factors that improve brain functioning, and exercise facilitates brain connections, the study says. \"Whether addressing our patients in primary care or neurology clinics, we should continue to encourage exercise for not only general health, but also cognitive health,\" Ahlskog adds. The findings were published in the Mayo Clinic Proceedings.