ARI SHAPIRO, HOST:
There's growing evidence that exercise can ward off Alzheimer's disease. Just this week, the idea got support from two new studies presented at a big international conference in Los Angeles. NPR's Jon Hamilton traveled on down the California coast to see how researchers are trying to prevent Alzheimer's by prescribing exercise as if it were a drug.
JON HAMILTON, BYLINE: It's called the EXERT Study, and participants take their medicine at local YMCAs like this one in Newport Beach. Francine Howard is a personal trainer here. She shows me one option for people whose prescription calls for aerobics exercise.
FRANCINE HOWARD: The participant would be on the treadmill for 45 minutes.
HAMILTON: Howard says personal trainers make sure every participant gets a full dose.
HOWARD: We are their cheerleaders. I love them, and I just want them to be successful. And they want to be successful also.
HAMILTON: Also to qualify for the EXERT Study, you need to be between 65 and 89 and not a regular exerciser. You also need to have mild cognitive impairment, a type of memory loss that often precedes Alzheimer's. Richard is 75 and enrolled six months ago. We're using only his first name to protect his privacy.
RICHARD: My memory isn't what it's supposed to be. My pockets are always filled with notes because that's what I do. I'm very bad with names.
HAMILTON: Richard says his wife learned about the EXERT Study from a flyer that came in the mail.
RICHARD: Within minutes, she was on the phone (laughter). And next thing I know, I'm being interviewed. They're taking my blood. They're wiring me up for things. And I'm in the program.
HAMILTON: So for the past six months, Richard has been going to the Y four days a week. He takes his training sessions seriously.
RICHARD: The only one I missed, I had some minor surgery that - the doctor said cool it for a week.
HAMILTON: The EXERT Study, funded by the National Institute on Aging, is designed to show whether aerobic exercise really can protect the brain. Laura Baker of the Wake Forest School of Medicine is the study's principal investigator.
LAURA BAKER: The evidence and science has been building for the last 20 years to suggest that exercise at the right intensity could protect brain health as we age and also protect against development of Alzheimer's.
HAMILTON: But much of that evidence has come from studies that were small, brief or relied on people's own estimates of how much they exercised. The EXERT Study is different. It takes people at high risk for Alzheimer's and randomly assigns them to one of two groups for 18 months, half to aerobic exercise like running on a treadmill. The other half do stretching and flexibility exercises for comparison. Baker says this is a lot like the way pharmaceutical companies test new drugs.
BAKER: We are testing if exercise is medicine for people with a mild memory problem.
HAMILTON: Researchers are tracking changes in memory and thinking. They're also monitoring blood flow in the brain, brain atrophy and levels of toxic proteins associated with Alzheimer's. Howard Feldman of the University of California San Diego says all that data will help make the results definitive.
HOWARD FELDMAN: We will not only understand whether the intervention helps people on a clinical outcome but actually what the scientific basis is.
HAMILTON: Richard isn't sure if his memory is any better, but he says going to the gym has changed his life.
RICHARD: The doughnut stop across the street, which I ignore every single time I come out - I used to love peanut butter-filled pretzels - haven't had one in six months. And as a result, I've lost eight pounds.
HAMILTON: It's been hard to find enough people like Richard, though. Andrea LaCroix of UC San Diego has been working to recruit more participants.
ANDREA LACROIX: It turns out to be super challenging to find people with memory problems who are willing to come to the Y four times a week and commit to being in the study for 18 months.
HAMILTON: The nationwide EXERT Study has enrolled about 200 people so far, but it needs 100 more.
Jon Hamilton, NPR News, Newport Beach, Calif.
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