Walking about a mile a day can increase the size of your gray matter, and greatly decrease the chances of developing Alzheimer's disease or dementia in older adults, a new study suggests.
"This is the first study that really looked over a several-year span and was able to assess this," said study author Kirk Erickson, an assistant professor of psychology at the University of Pittsburgh.
Erickson's study found that walking at least one mile per day significantly enhanced the volume of several regions of the brain, including the frontal lobe, which is involved in reasoning and problem-solving.
The researchers also found people who walked that distance reduced their risk of cognitive impairment by about half. However, walking more than one mile every day did not further improve brain volume.
Growing gray matter
Gray matter shrinks as adults age, increasing the potential for cognitive impairment and raising the risk of Alzheimer's disease and dementia, Erickson said. Approximately 5.1 million Americans may have Alzheimer's disease, according to the National Institute on Aging.
Previous studies by University of Illinois researchers have examined the effects of physical activity on brain function in the elderly over shorter time spans, from six months to one year, Erickson said.
However, in this study, participants were evaluated based on an initial measurement of walking, then followed for 13 years. People of this age may be prone to falls and illnesses that inhibit other daily exercise routines, he said.
"The fact that we can take a single snapshot of physical activity, and then use that to predict how much brain tissue you have nine years later, makes it all the more astonishing with the fact that we don't have to measure what kinds of physical activity you are doing in between," Erickson told MyHealthNewsDaily.
The study began with 299 dementia-free participants, ages 70 to 90, in 1989. Researchers measured how many blocks they walked per week and, at nine and 13 years after the initial examination, scientists assessed them with high-resolution magnetic resonance imagining (MRI).
In a final evaluation,116 of these people were diagnosed with dementia or mild cognitive impairment (MCI), which can lead to Alzheimer's disease, while 169 (excluding those deceased prior to the follow-up) remained free of these conditions.
Preventing and treating Alzheimer's
It's possible that exercise may be only postponing the onset of Alzheimer's disease in those vulnerable to the condition, Erickson said. But even if this is the case, the study points to potential prevention and treatment options for patients.
"Even if we are delaying [Alzheimer's disease] by several months or years, that's a significant improvement in what we know already, and a change in costs for treating health care," Erickson said. Delaying the condition could also ease the emotional burden and problems that come along with it, for both patients and their families, he said.
Further studies will examine how exercise may influence brain volume, including whether beginning an exercise regimen later in life can affect volume. The researchers will also look at the effects of physical activity on those already suffering with Alzheimer's disease, Erickson said.
"This is going to be an important avenue for future research, especially as there is a greater emphasis on, in the coming years, non-pharmaceutical ways to influence your risk for neurologic or psychiatric diseases," he adds.
The study is published online today in the journal Neurology. The work was funded by the National Institute on Aging.