Low Motor Function, Cognitive Decline Tied to Adverse Brain MRI Changes

Low motor function is associated with worse decline in memory, visuospatial ability, and perceptual speed, and in global cognitive function, according to the findings of a retrospective study published in Neurology.

Previous research has shown mixed results as to whether and how motor function is associated with cognitive health, especially with regard to individual cognitive domains.

For the current study, researchers leveraged data from the ongoing Rush Memory and Aging Project in Chicago and northeastern Illinois. Of participants recruited to this longitudinal study between 1997 and 2020, the researchers analyzed data for 1618 adults (mean age, 79; 74.2% women), without dementia at baseline or limitation in performing activities of daily living.

The researchers aligned data for each participant across multiple dimensions of health. They reviewed demographic, lifestyle, and cardiometabolic data, and the results of various tests of manual dexterity, grip strength, gait, and balance. They also collected baseline and follow-up test scores for episodic, semantic, and working memory; perceptual speed, and visuospatial ability.

From these scores emerged measures of global motor and cognitive function (the average z-scores across motor or cognitive domains). Diagnoses of dementia and mild cognitive impairment were also based on these tests, as well as on clinical neuropsychological evaluation.

Of the included participants, 344 had magnetic resonance imaging (MRI) data available. In a novel step, the researchers examined associations between motor function and both cognitive performance and MRI structural findings.

Over a median 6 years of follow-up, better motor function (both globally and for each component) was associated with slower cognitive losses (both globally and for each of the 5 domains; for the association between global motor function and global cognition β, .008; 95% CI, .007–.01).

When analyzed in tertiles of motor function, cognitive trajectories for the highest tertile diverged from those of both the moderate and low motor function tertiles. The presence of cardiometabolic disease strengthened this association; but it remained present in participants without cardiometabolic disease.

In MRI scans taken a median of 3 to 4 years after the baseline visit, participants with lower global motor function had smaller total brain volume (β, 50.995; 95% CI, 12.561–89.430), and greater volume of white-matter hyperintensities (β, -.476; 95% CI, -.758 – -.194). Those in the lowest tertile of motor function also had lower total and cortical white-matter volume; there were no differences in gray matter or hippocampal volume.

Noting the concomitance of total brain volume decrease, adverse white matter changes, cognitive decline, and motor functional loss, the researchers speculated that neurodegenerative and cerebrovascular diseases jointly mediated the association between cognitive and motor loss.

The study population skewed largely women, urban, and relatively highly educated; it was also unclear to what degree the findings apply to younger populations. Another limitation was lack of data on participants’ smoking history, hearing ability, and history of nondisabling motor disorders.

The researchers highlighted that “although many studies have reported an association between motor function and cognitive function, no study so far has incorporated brain MRI data, which could provide evidence regarding the mechanisms underlying the motor-cognition association.”

Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.