MINNEAPOLIS - Older adults who move more, either with daily exercise or even simple routine physical activity like housework, may preserve more of their memory and thinking skills, even if they have brain lesions or biomarkers linked to dementia, according to a study published in the January 16, 2019, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"Our research team measured levels of physical activity in study participants an average of two years prior to death, and then examined their brain tissue after death, and found that moving more may have a protective effect on the brain," said study author Aron S. Buchman, MD, of the Rush University Medical Center in Chicago and a member of the American Academy of Neurology. "People who moved more had better thinking and memory skills compared to those who didn't move much at all. We found movement may essentially provide a reserve to help maintain thinking and memory skills when there are signs of dementia present in the brain."

The study looked at 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. Participants agreed to donate their brains for research upon death. The average age at death was 91.

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, everything from small movements such as walking around the house to more vigorous movements 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.

After death, researchers examined the brain tissue of each participant, looking for lesions and biomarkers of dementia and Alzheimer's disease.

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

Buchman said analysis showed that physical activity and motor abilities accounted for 8 percent of the difference among people's scores on the thinking and memory tests.

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 people who had dementia and people who did not.

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.

"Exercise is an inexpensive way to improve health, and our study shows it may have a protective effect on the brain," said Buchman. "But it is important to note that our study does not show cause and effect. It may also be possible that as people lose memory and thinking skills, they reduce their physical activity. More studies are needed to determine if moving more is truly beneficial to the brain."

A limitation of the study was that it did not have data on how active participants were over the course of their lives, just at one point later in life, so it is unknown if physical activity in early life also may have played a role. Also, the study did not include the type of physical activity, so it is difficult to determine if one physical activity may be more beneficial than another.

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The study was supported by the National Institutes of Health, the Illinois Department of Public Health and the Robert C. Borwell Endowment Fund.

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The American Academy of Neurology is the world's largest association of neurologists and neuroscience professionals, with over 34,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, migraine, multiple sclerosis, concussion, Parkinson's disease and epilepsy.

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