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

BACKGROUND: 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.

METHODS: 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.

RESULTS: 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).

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