How exercise helps stave off Alzheimer’s

Now comes one more reason to get moving.

A recent study of more than 600,000 veterans found that those who were the most physically fit were the least likely to get Alzheimer’s disease.

“We know for a fact with other studies that people who exercise on a regular basis are at a lower risk for heart attack, stroke and dementia,” said neurologist Sean Horrigan, DO, of Neurologists of Cape Cod.

This latest study led by the Washington, D.C., Veterans Affairs Medical Center included 649,605 veterans who receive care at medical centers within the Veterans Health Administration (VHA), the agency announced in February. Participants, who averaged 61 years old, were monitored for nine years.

None of the participants had Alzheimer’s at the start of the survey. Over the nine years, their fitness was measured based on how well their muscles absorbed oxygen after a 30-minute session on the treadmill. They were then divided into five groups, based on the level of fitness; the group with the highest fitness level had an energy expenditure equivalent to about two hours of walking or biking per week. By the end of the study, members of that group were 33 percent less likely to develop dementia than those in the least-fit category.

But researchers said they also found that everyone except those in the least-fit category had some decrease in their risk of developing Alzheimer’s. “It was not an all-or-nothing proposition," said Edward Zamrini, MD, lead author. “People can work toward making incremental changes and improvements in their physical fitness and hopefully that will be associated with a related decrease in their risk of Alzheimer's years later.”

Oxygenation, Waste Removal, Neuroplasticity

There are several working theories as to why exercise is good for health, Dr. Horrigan said. For one, exercise stimulates the cardiovascular system, which optimizes oxygenation and blood flow to all our organs, he said.

“It also helps with removing metabolic waste, and cleaning out the body,” he said. “It's twofold: It's bringing things that are needed to our brain, to our other organs. It also helps to remove metabolic byproducts, waste from the organs, to make sure it's running more efficiently.”

Exercise also contributes to neuroplasticity, the ability of the brain to form and reorganize its synaptic connections or circuits. It releases a “chemical cascade” that helps to support the connection and growth of new neurons, he said.

“Exercising helps to boost nitric oxide, and that's a molecule that enhances blood flow,” he said. “It releases other factors that basically operate like Miracle-Gro for your brain.”

Promotes Healthy Sleep

Exercise also helps with promoting healthy sleep, which helps to prevent dementia, Dr. Horrigan said.

“Your brain is going into a restorative state when we're sleeping,” he said. “That's why it's ideal to try to hit seven hours of sleep.” Consistently sleeping less than seven hours or sleeping an excessive amount both seem to be linked with cognitive decline, he said.

If you’re worried your couch potato habits might be putting you at risk, rest assured that it’s never too late to start moving, Dr. Horrigan said.

“I always encourage my patients to exercise at least 30 minutes a day, at a minimum three days a week,” he said. “And, if you’re exercising five days a week, there’s a clear overall health benefit to maintaining such a healthy routine practice.”