Eating a healthy diet, getting regular physical activity, and maintaining a normal weight appear to reduce protein buildups in the brain associated with Alzheimer’s disease, according to a new study published in the September issue of the American Journal of Geriatric Psychiatry.
These lifestyle factors are already recommended for safeguarding against dementia, and have previously been shown to reduce shrinkage and atrophy of the brain. But this is the first study to demonstrate how they can directly influence abnormal protein growth in people who have subtle memory loss, researchers say.
This is significant, the study authors wrote in their paper, because it’s been estimated that up to half of Alzheimer’s cases can be attributed to modifiable risk factors such as low education, smoking, physical inactivity, and obesity. Even a 10 to 25 percent reduction in these risks could potentially prevent nearly 500,000 cases in the United States.
The study included 44 adults, ages 40 to 85, who’d been experiencing mild memory problems but had not been diagnosed with dementia. They provided information about their diet, exercise levels, body mass index (BMI), and other lifestyle factors. Then they were given a PET scan—a type of brain imaging test—to measure different levels of protein in their brain.
The researchers were looking for two specific types of protein: deposits of beta-amyloid plaque and knotted threads of tau protein tangles. Both types are considered key indicators of the development of Alzheimer’s disease.
Although the study could not prove a cause-and-effect relationship, it did find “moderate but significant” differences between participants with healthy lifestyles and people without. Specifically, people who got plenty of physical activity and had a normal BMI had fewer plaque deposits and tangles than those who got less exercise and had higher BMIs. The same went for those who followed a healthy diet—in this case, the Mediterranean diet—versus those who didn’t.
“The fact that we could detect this influence of lifestyle at a molecular level before the beginning of serious memory problems surprised us,” says lead author David Merrill, M.D., Ph.D., assistant clinical professor at UCLA’s Semel Institute for Neuroscience and Human Behavior.
Merrell says that doctors have long appreciated the fact that exercise and diet can improve muscle and heart function. But there seem to be additional effects they’re just starting to understand: “Some older patients of mine report similar benefits for their sharpness and memory on days when they go for a long walk or eat fish like salmon,” he says.
The new study reinforces the idea that habits that are good for the body are also good for the brain, says Merrill—and that they seem to have an impact on abnormal protein buildup “for years, if not decades, prior to the diagnosis of Alzheimer’s disease.”
In their paper, the authors also suggest that improving more than one of these lifestyle factors may lower Alzheimer’s disease risk more than focusing on any one factor alone. Luckily, they point out, eating healthier, getting more exercise, and losing weight often go hand-in-hand.
Merrell says it’s never too early, or too late, to adopt healthier habits—a belief he puts into practice when treating patients at UCLA. “We try to meet all patients and family members where they are,” he says, “recommending a guided increase in physical activity along with greater adherence to a Mediterranean style diet.” This helps to improve both their physical and mental health over time, he adds, no matter where they started.