Now, a recent post-mortem study suggests these benefits may extend to older adults, even those who have blood and brain biomarkers of Alzheimer’s disease and other brain pathologies. Higher levels of physical activity and motor abilities, such as balance, are linked to less cognitive decline in late life, according to a Neurology study published online on January 16. 

Studying Physical Activity, Brain Pathologies, and Cognition in Older Adults

To look more closely at the connection between physical activity, Alzheimer’s disease and other brain pathologies, and cognition, researchers from Rush University and the University of Toronto collected data from 454 participants in the Rush Memory and Aging Project (MAP), a community-based study of older adults who underwent annual detailed clinical examination and cognitive testing during a 20-year period. Participants agreed to donate their brain at the time of death for autopsies. Average age at death was 91; 73 percent were female.

A total of 21 cognitive tests were administered by trained technicians. The researchers calculated a cognition score, which can help predict the likelihood of dementia. They also measured 10 motor abilities, such as reduced walking speed and loss of balance, dexterity, and muscle strength and bulk.

The team measured total daily physical activity, including all exercise and non-exercise activities, continuously—24 hours a day for up to 10 days—with an accelerometer worn by participants on their nondominant wrist.

During brain autopsies, the researchers recorded evidence of Alzheimer’s by looking at neuritic plaques, diffuse plaques, and neurofibrillary tangles as well as beta-amyloid and tau tangles—markers of the disease—in the hippocampus and the frontal, temporal, parietal, and entorhinal cortex, brain regions involved in memory.

Higher Levels of Physical Activity Linked to Better Cognition, Motor Abilities

A total of 191 participants had been diagnosed with dementia. Participants without dementia averaged 180,000 counts of activity per day; those with dementia averaged 130,000 per day.

The researchers concluded that higher levels of daily physical activity and motor abilities were independently linked with improvements in semantic memory, episodic memory, working memory, perceptual speed, and visuospatial abilities, as measured by the annual cognitive tests.

In brain autopsies, an average of three brain pathologies were found in participants. The researchers reported more than 95 percent showed evidence of at least one brain pathology.

Questions Remain

The researchers were unable to ascertain if increased total daily activity improves cognition, or if lower cognition results in less physical activity. But they believe the findings "suggest that a more active lifestyle may provide cognitive reserve or resilience for older adults.” However, the mechanisms behind the association remain unknown.

Future research should include assessment of physical activity levels prior to the study and better monitoring of physical activities—accelerometers did not distinguish between steps versus arm movements, and the removal of the device could not always be classified as periods of no physical activity.