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  • Study: Physical Activity and Higher Motor Skills Create a 'Cognitive Reserve' Even When Brain Pathologies Are Present

    New research combining postmortem examination of brain tissue with testing during life has revealed what researchers believe to be an as-yet unexplained connection: higher levels of physical activity (PA) and motor skills seem to create a "cognitive reserve" that buoys cognitive performance during life, even in the presence of Alzheimer's disease (AD), Lewy body disease, and other brain pathologies associated with dementia.

    For the study, published ahead of print in Neurology (abstract only available for free), researchers examined brain tissue from 454 participants involved in the Rush Memory and Aging Project (MAP). The subjects participated in a battery of annual clinical assessments and agreed to brain donation at the time of death. The clinical tests included 21 cognitive assessments, an analysis of 10 motor abilities, and an estimation of total daily PA drawn from accelerometers worn constantly for 10 days (researchers in this study used only the first 7 days' data).

    After death, brain tissue was analyzed for AD, Lewy body disease, nigral neuronal loss, hippocampal sclerosis, and several other pathologies—10 in all. Researchers then compared the presence of these pathologies with PA, motor skills, and cognitive testing scores obtained during the participants' last MAP visit—typically about 2 years before death.

    Researchers weren't particularly surprised that participants who recorded higher levels of PA and motor skills during their last assessment also tended to score higher on cognitive tests than did those with lower PA and motor skills. What was more intriguing was that this association held up even in the presence of brain pathologies later revealed through tissue analysis. It wasn't that higher activity and mobility decreased the risk of the diseases themselves (although other studies have explored that possibility); it's that increased PA and mobility created what authors call a "cognitive reserve" that lowered the odds for and severity of dementia, even in the presence of AD or other degenerative brain conditions.

    "A more active lifestyle and better motor abilities proximate to death were independently associated with better cognitive function and reduced odds of dementia when controlling for AD and 9 other common age-related pathologies," authors write. "Moreover, there was also no evidence that a more active lifestyle or better motor abilities modified the associations of these brain pathologies with cognitive function prior to death." Authors believe that, together, these concepts point to the possibility that the cognitive reserve associated with PA and better motor skills are related to "molecular mechanisms…that remain to be identified."

    The researchers believe their study should be followed up with more work on the biological mechanisms that resulted in their findings, as well as explorations of which interventions might help to bolster cognitive reserve.

    Authors acknowledge several study limitations, including the lack of data on how active participants were prior to joining the MAP, no examination of other brain pathologies including white matter integrity, and the inability of the accelerometers to identify what kinds of PA were taking place. Still, they argue, the study's findings are important.

    "These findings suggest that a more active lifestyle may provide cognitive reserve or resilience for adults," the authors write, adding that the results "may have important public health implications because they suggest that resilience factors such as more cognitive activities or physical activity might mitigate late-life cognitive impairment even in the absence of effective therapies to reduce AD and other common brain pathologies."

    Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA. For synthesized research and evidence-based practice information, visit the association's PTNow website.

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