I'm hearing that exercise may offer protection from dementia. Is that true?

From the South Beach Diet

I started the South Beach Diet after reading that lowering cholesterol might help stave off dementia, which runs in my family. Now I'm hearing that exercise may offer protection. Is that true? — Taylor B., Lima, OH

Maybe. Scientists are just beginning to investigate the connection between an active lifestyle and a reduced risk for dementia — a condition of declining cognitive functions, ranging from memory loss and limitations in judgment to confusion. One recent study published in the Annals of Internal Medicine, January 17, 2006, found that people who exercised at least three times per week lowered their risk for dementia by 32 percent.

Another well-regarded study reported that men aged 71 to 93 who walked at least two miles a day reduced their risk by 40 percent compared with men who covered less ground. Still another study revealed that engaging in a variety of exercises is beneficial because learning multiple activities requires more memory and organizational skills than learning just one form of exercise.

As we await the results of more definitive clinical trials, I encourage everyone to get as much activity as possible. Exercise is known to reduce depression, which can exacerbate dementia, and it's been proven to lower blood pressure and raise HDL ("good") cholesterol, both of which benefit long-term cardiovascular health.