ISTANBUL

Taking as few as 3,000 steps a day may help older adults at risk of Alzheimer’s disease delay cognitive decline and harmful brain changes, according to findings from a 14-year study in the US.

The study, conducted by researchers at Mass General Brigham hospital in Boston and published in Nature Medicine, tracked 296 adults age 50 to 90 who showed no signs of cognitive impairment at the start. Participants were followed over 14 years using cognitive tests, pedometer data, and brain scans.

Researchers found that walking between 3,000 and 5,000 steps daily delayed cognitive deterioration by an average of three years, while those walking 5,000 to 7,000 steps saw delays of up to seven years.

“We’re encouraging older people who are at risk of Alzheimer’s to consider making small changes to their activity levels, to build sustained habits that protect or benefit their brain and cognitive health,” said Dr Wai-Ying Yau of Mass General Brigham hospital in Boston, as reported by The Guardian on Monday.

Dementia affects about 50 million people worldwide, with Alzheimer’s the most common type.

The disease is linked to two harmful proteins in the brain: amyloid-beta, which forms sticky plaques between nerve cells, and tau, which creates tangles inside brain cells and disrupts their function.

Those with low amyloid at the start of the study showed almost no decline. Among participants with higher amyloid levels, more daily steps were associated with slower cognitive decline and delayed tau buildup.

Sedentary individuals declined much faster, according to the study.

Researchers say exercise appears protective, though they cannot fully rule out that early Alzheimer’s leads to reduced activity.

“We need randomized clinical trials to prove cause and effect, but it’s very encouraging that physical activity may help to modify someone’s trajectory,” Yau said, adding that those with amyloid “could have a slower rate of decline if they’re more physically active.”

Scientists do not yet fully understand why exercise is beneficial, though improved blood flow, lower inflammation and its effects on hormone levels may all play a role.

“That is the million-dollar question we want to look at in future studies,” Yau said.