Associations of Upper-Extremity Exercise Capacity and Grip Strength With Cognitive Domains in Patients With COPD

Cognitive impairment (CI), which has been reported in COPD, has been related to physical performance. However, the association between CI and upper-extremity functions is unknown. We aimed to compare upper-extremity exercise capacity and grip strength between subjects with COPD with and without CI and to determine the relationship of upper-extremity functions with specific cognitive domains.

In this cross-sectional study, 76 subjects with COPD (mean age 66.8 ± 7.5 y, FEV₁% 47.12 ± 14.10) were classified as with and without CI according to the Montreal Cognitive Assessment. Clinical characteristics, upper-extremity exercise capacity (6-min pegboard ring test [6PBRT]), grip strength (hand dynamometer), dyspnea severity (modified Medical Research Council dyspnea scale), disease-specific health status (COPD Assessment Test), and disease-specific quality of life (St George Respiratory Questionnaire) were compared between groups, and the relationship of upper-extremity functions with cognitive subdomains was analyzed by multivariate regression analysis.

The number of 6PBRT rings (P = .01) and the grip strength (P = .033) were lower in subjects with CI. Subjects with CI had lower FEV₁% (P = .038), arterial oxygenation (P = .002), exercise habits (P = .033), health status (P = .01), quality of life (P = .042); and higher dyspnea (P < .001), smoking consumption (P = .032), emergency admission (P = .02), and hospitalization (P = .042). The adjusted model showed that executive functions and attention were related to upper-extremity capacity (β = 14.4 and β = 10.2, respectively) and hand-grip strength (β = 1.85 and β = 1.49, respectively).

These findings suggest that upper-extremity functions might be decreased especially concerning executive functions and attention in subjects with COPD with CI.