Does physical activity help your brain?
Research says yes, psychology department faculty member Kirk I. Erickson told an audience at the Hill House Kaufmann Center recently.
That may not be surprising, given that physical activity is known to be beneficial in staving off myriad physical ailments.
What may come as a surprise, however, is that exercise can bulk up the brain, particularly in areas associated with memory and cognitive function, said Erickson in a June 4 Walter Allen Memorial Seminar Series lecture sponsored by Pitt’s Alzheimer’s Disease Research Center, Alzheimer Outreach Center and the Alzheimer’s Association Greater Pennsylvania Chapter.
Erickson, of Pitt’s Center for the Neural Basis of Cognition and Center for Neuroscience, studies brain function and has published extensively on cognitive changes that occur as a function of physical health and aging. His research has shown that activity and exercise can enhance cognitive function across the lifespan, and that it doesn’t require long hours of grueling workouts.
“We have a lot of options,” he said. “We can sit around the house eating doughnuts or we can go for a walk. And this will influence the size of our brains. There’s more and more evidence.”
Regular walks at a brisk pace can result in measurable benefits. “Moderate intensity exercise several days a week is sufficient,” said Erickson, adding that studies have shown that starting late in life is not futile. “There’s no excuse,” he said. “You can become active and reap the benefits.”
It’s an important issue as an aging population is projected to result in higher rates of age-related diseases, including Alzheimer’s disease.
“We expect to see a higher proportion of adults over 65 in the coming decades,” he said, noting that 5.3 million people in the United States are living with Alzheimer’s disease in 2015, up from 5.1 million in 2010. The numbers are expected to rise to 13.5 million by 2050, assuming nothing changes in treatment and prevention techniques.
“Our health care system is wildly unprepared for this increase,” he said, adding that the cost is enormous. The Alzheimer’s Association estimates the cost of treating Alzheimer’s disease and caring for patients with the disease at $202 billion in 2015. That cost is expected to rise to more than $1 trillion by 2050.
“Alzheimer’s disease by itself could bankrupt our health care system,” said Erickson. “We need to do something and we need to do something soon.”
A 2011 study estimated that about 13 percent or 14.3 million Alzheimer’s disease cases worldwide potentially are attributable to physical inactivity, with about 1.1 million, or 21 percent, of U.S. cases linked to inactivity.
“Getting a small portion of people more active could go a long way in reducing the rates of Alzheimer’s disease,” he said, noting that a 10 percent reduction in these figures could prevent 380,000 cases worldwide, including 90,000 cases in the U.S.
Even in individuals without dementia, cognitive declines generally begin to be seen around age 60, with decreasing performance in such cognitive domains as spatial orientation, numerical and verbal reasoning.
Such declines are preceded by changes in the hippocampus — a part of the brain involved in memory formation — and in the prefrontal cortex. Both these regions of the brain shrink with age.
But is memory decline an inevitable consequence of getting older? Or can it be delayed or even prevented? “Those are important questions we still debate today,” Erickson allowed.
There’s great variability among individuals: “Some people show atrophy, some people show significant decline. Other people don’t,” he said.
What factors contribute to the variations? Is it simply good genetics? Or might diet, activity and intellectual engagement play roles?
And if we can identify those factors, can we develop interventions?
“This is where physical activity really emerges on the scene,” Erickson said.
“We’ve known for a long time being physically active is important to your muscles, for strength, for balance, for walking ability; for your heart and cardiovascular system — it reduces the risk of heart disease,” he said. “It’s important for metabolism, for type 2 diabetes, for different cardiovascular diseases.”
The heart and brain are closely linked, Erickson said. “If there’s something going on with your heart, it’s likely something is happening to the brain as well.”
So, if exercise is good for the heart, does it benefit the brain, too?
Research is mounting to show that exercise indeed is good for the brain.
A 2006 study found that people who reported being more physically active (exercising at least three times a week) show lower rates of dementia and remain dementia-free longer than those who are physically inactive, Erickson said. “It doesn’t stop dementia from occurring, but it does significantly reduce the rate of dementia,” he said.
“It’s been shown now over and over again: Engaging in some physical activity is a very effective way of reducing your risk for dementia,” he said. “People who are more physically active have almost half the chance of developing cognitive impairment compared with people who are inactive,” he said. “There’s a very large effect.”
Other research found that starting an exercise program has benefits: Study participants who took up brisk walking several times a week showed improvements across a broad range of cognitive tasks, he said.
Does exercise really have the power to change the brain?
Erickson’s own work in 2009 using MRIs in participants with an average age of 70 found a correlation between fitness levels and the size of study participants’ hippocampus.
Those who were less fit had smaller structures than those with higher fitness levels. “For the first time, we demonstrated that this structure that is critically involved in memory and Alzheimer’s disease is associated with fitness levels,” he said, adding that subsequent research found the pattern held in other age groups, including children and adolescents. “Higher fitness is associated with larger hippocampal volumes.”
MRIs of individuals with early-stage Alzheimer’s disease showed that more fit individuals still had larger hippocampal volumes, he said. “Remaining physically fit has a very strong, powerful and detectable effect on the size of brain regions that are critical to memory function.”
So, can getting active make your hippocampus larger?
After baseline assessments, sedentary older adults were divided into two activity groups: One half did brisk walking three times a week, while the other half did stretching and toning. After a year, the walking group not only improved their fitness levels more than the stretching/toning group, but also showed an increase in the size of the hippocampus.
How much exercise is needed to save your brain? “Generally, more is better,” but walking a mile a day can make a difference. “You don’t need a lot in order to gain a lot for your brain,” Erickson said.
Walking isn’t the only exercise: Swimming, bicycling, gardening or carpentry all are ways to get active. Erickson added that he soon will be recruiting subjects for a study on the effects of African dance on brain function.
“We want to develop a fun, engaging type of activity that might have some profound effect on keeping people adherent — keeping people engaged — but also for improving memory and cognitive function,” he said.
“I don’t know of any pharmaceutical that has the potential to have the same effect,” on the brain as what’s been shown by simply getting active, he said.
“This is not paying a lot of money for pills or computer games. This is just a good pair of walking shoes.”
Details on Erickson’s current studies can be found at the Brain Aging and Cognitive Health Lab web site at www.pitt.edu/~bachlab/LabSite/.
—Kimberly K. Barlow