Just 20 minutes of exercise improves memory

The Seatle PI reports:

Adding even a small amount of exercise to a person's daily routine can reduce the risk of developing Alzheimer's disease, according to a study published in Wednesday's Journal of the American Medical Association.

The study, by Australian researchers, showed that six months of physical activity -- averaging about 20 minutes a day -- in volunteers 50 and older modestly improved memory and cognition.