The Relationship Between Cognitive Impairment and Upper Extremity Function in Older Primary Care Patients

Individuals with mild cognitive impairment (MCI), often a precursor to dementia, experience limitations in completing daily activities. These limitations are particularly important to understand, as they predict risk for dementia. Relations between functional changes and both cognitive decline and upper extremity motor impairments have been reported, but the contribution of motor function to relations between cognitive function and functional independence remains poorly understood. We examined the relationship between cognition and upper extremity activities, and whether this relation was mediated by motor function.

A total of 430 community-dwelling primary care patients aged at least 65 years from the Boston Rehabilitative Impairment Study of the Elderly completed self-report measures of upper extremity function, tests of neuromuscular attributes to measure motor function (reaction time, pronosupination of the hands), and neuropsychological measures. Participants were classified based on cognitive performance into groups: MCI and without MCI, with MCI further classified by cognitive subtype. Regression and mediation analyses examined group differences and relations between cognitive function, upper extremity function, and neuromuscular attributes.

MCI participants demonstrated poorer neuromuscular attributes and self-reported upper extremity function, and neuromuscular attributes significantly mediated positive relations between cognitive status and self-reported upper extremity function. Poorer self-reported upper extremity function was most prominent for groups with executive dysfunction.

Together with previous research, results suggest that the relationship between cognitive function, motor function, and functional activities is not confined to mobility tasks but universally related to body systems and functional activities. These findings inform new approaches for dementia risk screening and rehabilitative care.