How Exercise May Ward Off Alzheimer’s

April 4, 2012

A daily walk or jog may help to ward off the memory loss of Alzheimer’s, a new study suggests, particularly in people at increased risk of the disease.

The study, which appeared in the Archives of Neurology, was among the first to look at people’s activity levels and whether they carried a gene called APOE-E4, which increases the risk of developing Alzheimer’s in old age. People who have the gene are at up to 15 times increased risk of getting Alzheimer’s, though carrying the gene only heightens risk and does not mean you will get the disease.

Researchers found that people with APOE-E4, which may be carried by around 20 percent of the population, who were physically active had fewer plaques in their brains compared to less active carriers of APOE-4. The buildup of plaque, composed of a toxic protein called beta-amyloid, is linked to the memory loss of Alzheimer’s. People with Alzheimer’s tend to have lots of beta-amyloid buildup in their brains, and the more beta-amyloid, the worse memory and thinking skills tend to be.

For the study, researchers at Washington University in St. Louis looked at 210 men and women, ages 45 to 88, none of whom had serious memory problems. They were tested to see whether they carried the APOE-E4 gene, and most also underwent spinal taps and specialized brain scans to look for signs of beta-amyloid. They were also asked about their regular exercise habits during the previous 10 years.

The researchers found that those adults who tended to be active and get plenty of exercise had less buildup of beta-amyloid than those who were sedentary, particularly in parts of the brain important for memory and thinking. They also found that people who carried the APOE-E4 gene had more beta-amyloid accumulation than those without the gene.

The combination of carrying the APOE-E4 gene and being sedentary was a particularly destructive combination. People without the gene who did not exercise had some beta-amyloid buildup in their brains, but far less than those who carried the gene. The relationship held even after considering factors like advancing age, obesity, or having diabetes or depression, all of which increase the risk of developing Alzheimer’s.

Exercise, though, appeared to benefit those who carried the APOE-E4 gene. Carriers who walked or jogged regularly had less plaque buildup in the brain. The authors note that, “In summary, our findings suggest that exercise at levels recommended by the American Heart Association may be particularly beneficial in reducing the risk of brain amyloid deposition in cognitively normal APOE-E4-positive individuals.”

The American Heart Association recommends that all adults, including older ones, strive for an “active lifestyle.” That means getting at least 150 minutes per week of moderate exercise, or 75 minutes per week of vigorous exercise, or a combination of both moderate and vigorous activity. That translates to 30 minutes a day, five times a week, though they also note that getting short bursts of activity – say 10 to 15 minutes a few times a day – is also effective. Climbing stairs, playing a sport, walking, jogging, swimming or biking all count. The group also recommends strength and stretching exercises that build overall stamina and flexibility.

Walking, the American Heart Association notes, may be especially apt choice for beginners or older adults. Several studies have shown that people who walk regularly have a lower Alzheimer’s risk, and may have brain changes that promote cognitive health. See, for example, the ALZinfo.org story, “Walk to Keep the Memory Sharp” at Walk to Keep the Memory Sharp.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Head D, Bugg JM, Goate AM, et al: Exercise Engagement as a Moderator of the Effects of APOE Genotype on Amyloid Deposition. Archives of Neurology.
Published online January 9, 2012. doi:10.1001/archneurol.2011.845.


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