Regular physical activity in old age may protect brain from dementia

Exercising regularly, or even undertaking routine housework, may help preserve thinking and memory skills in older adults who have developed early symptoms of Alzheimer's disease.

The research showed that exercise is an inexpensive way to improve health, create protective effect on the brain.

"We measured levels of physical activity in study participants an average of two years prior to their deaths, and then examined their donated brain tissue after death, and found that a more active lifestyle may have a protective effect on the brain," said Aron S Buchman, from Rush University in the US.

"People who moved more had better thinking and memory skills compared to those who were more sedentary and did not move much at all," said Buchman, lead author of the study published in the journal Neurology.

The researchers found movement may provide cognitive reserve to help maintain thinking and memory skills when there are signs of Alzheimer's disease pathology present in the brain.

The study assessed 454 older adults; 191 had dementia and 263 did not. All participants were given physical exams and thinking and memory tests every year for 20 years.

The participants agreed to donate their brains for research upon their deaths. The average age at death was 91 years.

At an average of two years before death, researchers gave each participant an activity monitor called an accelerometer.

The wrist-worn device monitored physical activity around the clock, including everything from small movements such as walking around the house to more vigorous activity like exercise routines.

Researchers collected and evaluated seven days of movement data for each participant and calculated an average daily activity score. The results were measured in counts per day, with an overall average of 160,000 counts per day.

People without dementia had an average of 180,000 counts per day, and people with dementia had an average of 130,000 counts per day.

Researchers found that higher levels of daily movement were linked to better thinking and memory skills.

The study also found that people who had better motor skills -- skills that help with movement and coordination -- also had better thinking and memory skills.

For every increase in physical activity by one standard deviation, participants were 31 per cent less likely to develop dementia.

For every increase in motor ability by one standard deviation, participants were 55 per cent less likely to develop dementia.

Buchman said analysis showed that physical activity and motor abilities accounted for eight percent of the difference among people's scores on the thinking and memory tests.

After participants' death, researchers examined their donated brain tissue, looking for lesions and biomarkers of dementia and Alzheimer's disease.

The relationship between activity and test scores was consistent even when researchers adjusted for the severity of participants' brain lesions. They also found that the relationship was consistent in both people who had dementia and people who did not have dementia.

The link between a higher level of physical activity and better thinking and memory skills was unrelated to the presence of biomarkers of Alzheimer's disease and related disorders.