A large analysis of nearly 200,000 competitive cross-country skiers confirms what many other studies have shown: physical activity not only helps build strength and stamina and may help to lower the risk of heart disease and other ills, it may also be good for the brain. But whether exercise can actually help to stave off Alzheimer’s disease remains unproven.
“As brain researchers, we have had the unique opportunity to analyze an exceptionally large group of very physically active people over two decades, and we have unraveled some interesting results,” said Tomas Deierborg, the research team leader and associate professor at Lund University in Sweden.
For the study, researchers studied 197,865 men and women who had participated in the Vasaloppet, a popular cross-country skiing race in Sweden, between 1989 and 2010. They compared them with a similar-sized group of their peers from the general population.
Two decades after the skiers had competed in the race, 233 had developed Alzheimer’s disease or other forms of dementia. Eighty-six of them had been given a diagnosis of Alzheimer’s disease, and 40 had been diagnosed with vascular dementia, a result of blood vessel problems in the brain.
Among the control group in the general population, 319 had developed dementia, including 95 diagnoses of Alzheimer’s disease and 72 cases of vascular dementia.
The researchers calculated that among the skiers, a physically fit group, there was a 50 percent reduced risk of developing vascular dementia than among the control group. The ski group also had a lower risk of heart disease, depression and Parkinson’s disease. The risk of developing Alzheimer’s disease, however, was not statistically lower in this study.
The findings underscore the difficulty of pinpointing which lifestyle factors may reduce the risk of developing Alzheimer’s disease over the long term. Other studies have found, for example, that regular physical activity has benefits for the brain and may reduce the risk of developing Alzheimer’s disease. Studies have shown that even modest physical activity, like walking at a brisk pace, may help to lower the risk of Alzheimer’s and other forms of dementia. But people who exercise regularly also go on to develop Alzheimer’s disease.
Other studies have shown that exercise can have benefits for those who already have Alzheimer’s disease. In one study, people with Alzheimer’s disease who participated in a home exercise program, for example, showed less frailty and were less likely to fall, a concern for any older person. Getting exercise also led to modest improvements in day-to-day activities like getting dressed, walking and eating. Any improvements in these activities can allow those with Alzheimer’s to remain at home longer and delay the need to enter a nursing home.
Scientists propose several reasons why exercise may benefit the brain. Physical fitness has been shown to benefit blood vessels, including those in the brain, and good blood flow to the brain may be critical for maintaining our brain in a good shape and therefore memory and thinking. Physical activity has also been shown to boost the growth of new nerve cells in the brain, especially in a brain region important for memory, and release various growth factors important for nerve cell maintenance.
Many people with Alzheimer’s disease also have blood vessel problems in the brain, and vascular dementia and Alzheimer’s can overlap. Any activities that benefit the brain can be good for those with Alzheimer’s disease, as well as those without it.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Oskar Hansson, Martina Svensson, Anna-Märta Gustavsson, et al: “Midlife physical activity is associated with lower incidence of vascular dementia but not Alzheimer’s disease.” Alzheimer’s Research & Therapy, Vol. 11, December 2019