Study finds moderate step count daily may delay cognitive decline by 7 years

New Delhi, Nov 7 (PTI) Walking up to 5,000 steps everyday may help delay cognitive decline by three years on average while 7,500 steps daily may delay it by seven years, a study in around 300 individuals has found.

Sedentary individuals were seen to have a significantly faster buildup of tau proteins in the brain -- contributes to neuron death and is considered a hallmark of Alzheimer's disease -- and more rapid declines in cognition and daily functioning.

"Lifestyle factors appear to impact the earliest stages of Alzheimer's disease, suggesting that lifestyle changes may slow the emergence of cognitive symptoms if we act early," senior author Jasmeer Chhatwal from the Mass General Brigham, a US-based health care system, said.

"(The study) sheds light on why some people who appear to be on an Alzheimer's disease trajectory don't decline as quickly as others," Chhatwal said.

Alzheimer's disease is an ageing-related disorder, in which one's memory, speech and thought processes can steadily decline, eventually hampering everyday functioning.

The analysis, published in the journal Nature Medicine, looked at data from 296 participants aged 50-90 years old in the 'Harvard Aging Brain Study', all cognitively unimpaired at the study's start.

Positron emission tomography (PET) brain scans were used to measure amyloid-beta in plaques and tau in tangles -- both refer to accumulation of proteins in brain and are symptoms of Alzheimer's -- and assessed the participants' physical activity using waistband pedometers. The participants were followed-up for up to 14 years.

"Higher physical activity was associated with slower amyloid-related inferior temporal tau accumulation, which significantly mediated the association with slower cognitive decline," the authors wrote.

"Associations with more favourable tau and cognitive trajectories reached a plateau by moderate levels of physical activity (5,001-7,500 steps per day)," they said.

The team said that most of the benefits from physical activity linked to a slowing down of cognitive decline were driven by a slower tau buildup.

By contrast, in people with low levels of amyloid-beta to begin with, there was very little cognitive decline or accumulation of tau proteins over time and no significant associations with physical activity, the researchers said. PTI KRS NB