Here's what the column had to say on that matter:
As the population continues to age, perhaps the greatest health benefit of regular physical activity will turn out to be its ability to prevent or delay the loss of cognitive functions. The new study of 3,485 healthy men and women older than 55 found that those who were physically active three or more times a week were least likely to become cognitively impaired.
One study conducted in Australia and published in September 2008 in The Journal of the American Medical Association randomly assigned 170 volunteers who reported memory problems to a six-month program of physical activity or health education. A year and a half later, the exercise group showed “a modest improvement in cognition.” Various other studies have confirmed the value of exercise in helping older people maintain useful short-term memory, enabling them to plan, schedule and multitask, as well as store information and use it effectively.