The Culture Fair Intelligence Test is designed to assess fluid intelligence, and past evidence has shown that increasing age is associated with a decrease in performance on this task. The results of this study support this conclusion because age predicted a significant portion of the variance in performance and was negatively related to performance. Additionally, past cross-sectional research has provided support for the hypothesis that greater levels of aerobic fitness may be associated with a lessening of the normal age-related declines in cognitive functioning. This conclusion was also supported by the results of this study because a significant portion of the variance in fluid intelligence performance was explained by performance on the 6-min walk test and the direction of this relationship was positive. Thus, in a COPD sample of older adults, age is negatively associated and aerobic fitness is positively associated with fluid intelligence. The strength of this relationship is also worthy of mention because these variables were able to predict 28% of the variance in performance after we controlled for education and depression. so
Some may question why performance on the 6-min walk test was a significant predictor of performance while Vo2peak was not a significant predictor. Evidence suggests that even in normal older populations, as many as half of the participants may be unable to attain true maximum oxygen uptake. Additionally, older patients with chronic diseases often become exhausted after a short time period during conventional maximal exercise testing, and some patients with COPD may terminate an exercise test early because of difficulty with the mouth piece. As a result, maximal or peak aerobic capacity may be underestimated. Because of these limitations, the 6-min walk test may be considered a better measure of the patient’s functional capacity. If this is true, then the findings of this study are in line with past research with normal samples and provide further support for the idea that aerobic fitness may serve to ameliorate age-related declines in cognitive functioning.