Yes, it's true. Scientific research studies show that exercise greatly lowers your risk of dementia and your risk of Alzheimer's, the most-feared form of dementia.

Swedish scientists found that those who engaged in "leisure time physical activity" at least twice a week in middle age had a 50 percent lower chance of developing dementia, and a 60 PERCENT LOWER CHANCE OF DEVELOPING ALZHEIMER'S DISEASE, when compared with their more sedentary colleagues, according to a study published in October, 2005, in Lancet Neurology.

But, if you're already up in years, it's not too late to start. The Nurses' Health Study, which interviewed 18,766 US women aged 70 to 81 years, found that those who walked at least 1.5 miles a week had the least thinking impairment. The researchers have been following the health and physical activity of these women since 1986 and have tested their thinking abilities over the years. And women who were more physically active had significantly less decline in their thinking abilities as they aged.

Also, the Honolulu-Asia Aging Study interviewed 2,257 men between 71 and 93 years of age. They found that MEN WHO WALKED TWO MILES PER DAY HAD HALF THE RISK OF DEMENTIA, compared with those who walked less than a quarter mile per day.

So, whether you start early or late, exercise really does prevent Alzheimer's.

EXERCISE AND ADD NEW BRAIN CELLS

Yes, exercise not only helps you avoid Alzheimer's, it actually adds brain cells! Through a special MRI imaging technique, researchers at Columbia University were able to watch "neurogenesis," the growth of neurons or nerve cells, within a living person's brain. And it happened right after exercise.
(The study was published in the March 12-16, 2007, Proceedings of the National Academy of Sciences.)

So exercise doesn't just "clear the brain." It adds to the brain while preventing Alzheimer's.