Chest
Volume 116, Issue 4, October 1999, Pages 953-960
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Clinical Investigations
AIRWAY DISEASE
The Relationships Among Pulmonary Function, Aerobic Fitness, and Cognitive Functioning in Older COPD Patients

https://doi.org/10.1378/chest.116.4.953Get rights and content

Study objectives

To study the predictive relationships among age, pulmonary function, aerobic fitness, and cognition in people with COPD.

Design

Observational study conducted during baseline testing with COPD patients who volunteered to participate in an exercise intervention.

Participants

Older adults (age, 56 to 80 years) with COPD.

Measurements and results

Age, depression, education level, aerobic fitness, blood oxygen saturation levels, and pulmonary function were assessed. Participants were randomly assigned to take cognitive tests of (1) fluid intelligence, (2) processing speed and working memory span, or (3) processing speed and inhibition. After controlling for education and depression (F2,57 = 7.43; r2 = 0.21), performance on the 6-min walk (F1,56 = 15.27; r2 = 0.17) and age (F1,55 = 7.52; r2 = 0.08) were significant predictors of fluid intelligence. On the speed-of-processing task, performance on the 6-min walk (F1,30 = 8.17; r2 = 0.20), maximum voluntary ventilation (F1,29 = 5.81; r2 = 0.16), and age (F1,28 = 5.26; r2 = 0.10) were significant predictors. FVC was a significant predictor (F1,25 = 6.37; r2 = 0.18) of working memory span. The ability to inhibit a response was not significantly predicted by any of the variables assessed.

Conclusions

In an older COPD sample, age, aerobic fitness, and pulmonary function are predictive of cognitive performance on various tasks. In particular, age and aerobic fitness are predictive of speed of processing, which is a cognitive variable that may itself underlie performance on a majority of cognitive tasks.

Section snippets

Participants

Participants were 98 individuals who were taking part in the Reconditioning Exercise and COPD Trial (REACT). The REACT study is an 18-month exercise intervention in which all participants complete 3 months of exercise before being randomly assigned to either return to their normal lifestyle or to continue exercising for an additional 15 months. For the purposes of this study, only data from the initial screening visits were examined. Individuals with COPD were recruited from the community

Results

There were a total of 98 participants in the study, ranging in age from 56 to 80 years old. Of these 98 subjects, data is available for 60 people who completed testing for Fluid, 34 people who completed Speed, 29 people who completed Span, and 31 people who completed Stopping. Descriptive data for each of the subsamples tested is presented in Table 2.

Discussion

It has been proposed that the mechanism underlying the negative relationship between age and cognitive functioning is cerebral oxygenation.3 Further, it has been proposed that an explanation for individual differences in cognitive functioning among older adults may be aerobic fitness level because of its impact on cerebral oxygenation.3 Patients with COPD may have a reduced

o2peak for several reasons. These patients may be limited by their cardiovascular system, similar to normal healthy

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