3,000 steps per day might slow Alzheimer’s disease

Taking just a few thousand steps daily could potentially stave off Alzheimer’s disease. 

People with the disease tend to experience debilitating cognitive challenges, like memory loss and difficulty communicating, that worsen over time. But physical activity may slow that steady downward march.

In an observational study of people at risk for Alzheimer’s, researchers linked walking between 3,000 and 5,000 steps per day to a three-year delay in cognitive decline, compared with sedentary individuals. For people who walked between 5,000 and 7,500 steps per day, the reprieve appeared to last even longer — seven years, Harvard Medical School behavioral neurologist Jasmeer Chhatwal and his colleagues report November 3 in Nature Medicine.

The association still needs to be tested in a clinical trial, Chhatwal says, but his team’s results hint at something important. Quality of life for people with Alzheimer’s and their families often plummets in the later stages of the disease. “If the disease can be delayed,” he says, “that can have a very big impact on people’s lives.”

Previous studies have reported links between physical activity and delayed Alzheimer’s progression, says Deborah Barnes, an epidemiologist who studies dementia at the University of California, San Francisco, and who was not part of the research team. But the new study pinpoints the step count where people begin to see benefits. It also “helps to explain how,” she says.

Chhatwal’s team reported a connection between exercise and less accumulation of certain Alzheimer’s proteins in the brain. It’s a mechanism that illustrates how physical activity probably works to slow Alzheimer’s progression, Barnes says.

Alzheimer’s disease is the most common form of dementia. In the United States, dementia affects more than 6 million people, and case counts are rising. As the population of older people grows, scientists predict that 1 million adults per year will develop the condition by 2060, reaching a total of nearly 14 million cases. There’s currently no cure. “But there may be things that [people] can do to delay or prevent the onset of symptoms,” Chhatwal says.

His team analyzed data from nearly 300 people, ages 50 to 90, who had no cognitive issues at the start of the study. Researchers tallied the participants’ daily step counts for a week, tested their cognitive abilities and scanned their brains to look a protein called amyloid beta, which can be an early indicator of Alzheimer’s disease.

People who have this indicator may feel a sense of inevitability that they’re going to decline over time, says Chhatwal. “But the reality,” he says, “is that a lot of people actually do pretty well.” He wanted to figure out what distinguishes people who fare well from those who don’t.

Chhatwal’s team followed the study participants over nine years, on average, performing cognitive tests annually. The researchers also repeated the brain scans multiple times over the study period to track both amyloid beta and another protein called tau. Tau forms tangles in the brains of people with Alzheimer’s and builds up after amyloid beta accumulates. It’s a sign of disease progression.

People at risk of developing Alzheimer’s disease ­based on their initial brain scans had less tau buildup over time if they were at least somewhat active, the team found. That’s compared with people who walked less than 3,000 steps per day. And less tau buildup generally meant more cognitive function. Minimally active people, those who logged 3,000 to 5,000 daily steps, saw 40 percent less cognitive decline than sedentary individuals, the researchers observed.

“The most important takeaway is that you start to see the benefits of exercise with as little as 3,000 steps a day,” Barnes says. That’s about 30 minutes of daily walking.

Chhatwal hopes that people with a high genetic risk for Alzheimer’s feel empowered by the results. Physical activity may be one thing they can do to delay symptoms, he says. And, as scientists have shown with other health conditions, people can see gains with very little pain. “What I tell my own patients,” he says, “is that every little bit counts.”