Nobody really knows how exercise helps prevent loss of mental function, but every factor that helps protect you from getting a heart attack or stroke also protects you from dementia. Anything that protects blood vessels also protects your brain. Heart attacks and dementia are associated with eating too much fat, saturated fat, fried foods, refined carbohydrates, too many calories, and not eating enough vegetables, nuts, beans and other seeds; being overweight, not exercising, taking more than two alcoholic drinks a day, and smoking.

The statin drugs that are commonly used to help prevent heart attacks have also been shown to help prevent dementia. Again, we see that almost everything that helps prevent heart attacks also appears to help prevent Alzheimer's disease. The statin drugs appear to help by increasing blood flow and decreasing inflammation, independent of their cholesterol-lowering actions. Exercise may do the same things.

The Nurses' Health Study from the Harvard School of Public Health has shown that exercising your muscles improved cognitive function in older women (Journal of the American Medical Association, September 2004). Another study shows that more than 85 percent of middle-aged people who start an exercise program drop out in the first six weeks. You're more likely to continue if you exercise with others: a spouse or friend, with a personal trainer, or in an organized group or class.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.