Long before Alzheimer’s disease is diagnosed – before it robs one of language, judgment and temperament – a person capable of normal daily activities starts to have trouble remembering things.
This early form of memory loss is considered a harbinger of Alzheimer’s disease, which affects upward of 5.1 million people in the United States.
Researchers at the University of Wisconsin-Milwaukee are studying whether exercise can stall this form of memory loss – called amnestic mild cognitive impairment, or aMCI – and stave off the progression of Alzheimer’s disease.
By delaying the onset of Alzheimer’s by just five years, the number of people affected by the disease could be cut in half, says J. Carson Smith, assistant professor of health sciences at UWM and the study’s lead investigator.
With rare exception, Alzheimer’s is a disease of an aging brain. According to the National Institute of Aging, most cases occur after age 60. About 40 percent of those who develop the disease have a genetic risk factor.
In a paper published last month in the journal Psychiatry Research, Smith and his colleagues used neuroimaging – functional magnetic resonance imaging, or fMRI – to compare blood flow in the brains of subjects with aMCI who had either been physically active or inactive.
Smith tested a particular type of memory, called semantic memory, which allows the brain to distinguish word meanings.
In this study, subjects were asked to discriminate between famous and unfamiliar names. When semantic memory was triggered, subjects who participated in physical activity showed enhanced blood flow to a piece of brain anatomy called the caudate nucleus.
The role of this part of the brain in memory isn’t well understood. Studies have mostly focused on the hippocampus, a seahorse-shaped brain structure critical to learning and memory which is damaged during the progression of Alzheimer’s disease.
Smith says the caudate nucleus is important because it plays a supportive role in semantic memory – the ability to differentiate, for example, a recognizable name like Frank Sinatra from that of a stranger.
Alzheimer’s disease affects memory of past events, but it also inhibits semantic memory, thus eventually preventing a person from readily naming objects and people.
“These are pilot studies that will lead to looking at whether exercise is changing brain function or structure,” Smith says. “Future studies will explore how those changes relate to cognitive function over time.”
What isn’t clear is how much exercise is required to delay memory loss.
“Minimal physical activity will offer a positive effect,” Smith says, “but the benefit of high-intensity exercise we don’t know yet.”
He is, however, certain of the value of an active lifestyle: “If you are sedentary and have genetic risk for Alzheimer’s disease, you are at risk for decline.”
Paul Thompson, professor of neurology at University of California Los Angeles School of Medicine, agrees that staying active might be a good habit to adopt.
“This type of evidence is a pretty good motivator to get up off the couch,” he says, “especially if you’re worried about staying mentally sharp.”
Smith and collaborators at Marquette University and the Medical College of Wisconsin are conducting studies until December, which will help the researchers determine if exercise is changing brain function or structure over time.
Volunteers, ages 60 to 88, will be given tests of memory, motor function and mood, and screened for a genetic marker of the disease. During the course of the 12-week study, participants will also undergo two fMRI brain scans.
The scans provide researchers a glimpse into how the brain functions, such as how blood flows to specific parts of the brain, based on the magnetic properties of iron-containing red blood cells.
Study participants who can safely exercise and who meet study criteria will be assigned a fitness trainer and expected to build their endurance on a treadmill to 30 minutes of exercise, four days a week.
Study coordinator Karen Outzen says that some study volunteers have memory problems, but many do not.
“Most are concerned about their own memory or have a loved one who has dealt with aMCI or Alzheimer’s disease,” Outzen says.
One concern for study subjects, says Smith, is being confined in an fMRI machine.
For study participant Sister Lenore Steilen, 88, time spent in the machine was an opportunity to relax.
A retired teacher who volunteers as a baker at St. Ann Center for Intergenerational Care in Milwaukee, Steilen says that with the help of fitness trainers, she gradually improved her endurance on the treadmill.
“Afterward, I would sit down and rest for a bit,” she says, “but I never felt any negative results.”
Her participation in the study motivated her to continue to walk recreationally.
Smith says fear of the unknown is another issue for potential volunteers.
“Alzheimer’s disease is the second most feared disease next to cancer,” he says. “Some are in denial and don’t want to get involved. Others are concerned about a genetic link that may exist in their family.”
To recruit study subjects, Smith gives seminars about memory loss and Alzheimer’s disease at assisted living facilities and community organizations.
He says study participants ultimately decide to enroll because they want to take action.
“There is hope for exercise in the fight