Doctor’s Tip: The importance of exercise in preventing Alzheimer’s
Last week’s column was an overview of Alzheimer’s disease, which affects 20 percent of Americans between 75 and 84, and 50 percent of Americans 85 and older. Today’s column will discuss how exercise helps prevent this disabling disease.
Neal Barnard, M.D., is the founding president of Physician Committee for Responsible Medicine, and one of the giants in nutrition research. He has written several books, including “Power Foods For The Brain, An Effective 3-Step Plan to Protect Your Mind and Strengthen Your Memory.” The three steps are diet; exercise; and avoiding common physical threats to brain health such as sleep disruptions and certain medications and medical conditions.
Here are some of the studies that show that physical exercise is important for optimal brain health:
• In a Columbia University study, deconditioned people in the 21-45 age range were asked to exercise for 40 minutes, four times a week for 12 weeks. Brain MRIs were done before and after the study began. After 12 weeks of exercise the exercisers’ brains had developed new blood vessels and brain cells.
• A University of Illinois study involved 59 sedentary people over age 60. After six months of aerobic exercise three times a week, their brains were larger than on pre-exercise MRIs.
• The hippocampus is a part of the brain that is important in short and long-term memory, and it typically shrinks by about 1-2 percent per year. In a study, 120 older sedentary adults were asked to start a simple walking program, starting at 10 minutes and working up to 40 minutes three times a week. Brain MRIs done before and after showed that the hippocampus in these exercisers increased in size. Memory performance also improved.
• A study done by researchers in Seattle’s Group Health Cooperative looked at adults over age 65 and found that those who exercised three times a week were 40 percent less likely to develop dementia.
• Swedish researchers found that active people were 60 percent less likely to develop Alzheimer’s compared to couch potatoes. The positive effect of exercise was particularly evident in those with the ApoE4 gene — a gene that increases the risk of Alzheimer’s (an example of how “genetics loads the gun, but environment pulls the trigger” — so exercise helps prevent the trigger from being pulled in these people).
According to Dr. Barnard, the explanation for why exercise prevents Alzheimer’s is twofold: Exercise plus a healthful diet keeps “your arteries clear and open, maintaining a good blood supply,” enabling oxygen to get into the brain and wastes to come out. The second part of the explanation involves brain-derived neurotrophic factor, which “helps the brain grow new connections … between brain cells and protects the cells and connections you already have.” Aerobic exercise increases brain BDNF.
How much should you exercise? The recommendations are the same as for optimal cardiovascular health. In his book “How Not to Die,” Dr. Greger recommends 90 minutes a day of moderate-intensity exercise (e.g. bicycling on the level, dancing, downhill skiing, hiking, housework, brisk walking) or 40 minutes of vigorous activity (e.g. bicycling uphill, cross-country skiing, jogging, swimming laps). However, huge benefits occur from even mildly-intense exercise, and I tell my patients to exercise aerobically at least 30 minutes a day, hard enough so they can talk but not sing.
Dr. Feinsinger, who retired from Glenwood Medical Associates after 42 years as a family physician, has a nonprofit Center For Prevention and Treatment of Disease Through Nutrition. He is available for free consultations about heart attack prevention and other medical issues, and to help people with hospital or other medical bills they don’t understand or think are too high. Call 970-379-5718 for an appointment. For questions about his columns, email him at firstname.lastname@example.org.