There has been particular interest in studying the impact of cognitive changes in individuals with Chronic Obstructive Pulmonary Disease (COPD). This population can have decreased cognition for any number of reasons including age-related declines in blood flow, disease-related declines in blood flow which affects oxygen transport to the brain, and both age and disease related declines in physical activity. PURPOSE: The purpose of the original study is to investigate the relationship between age, psychological well-being, health related quality of life (HRQL), six-minute walk distance (6MWD), seven-day physical activity recall (7DPAR), vocabulary subtest scores, pulmonary function values and five specific cognitive domains (motor speed, perceptual motor speed and sequencing, inhibitory processing, verbal fluency, and psychomotor performance) in a sample of people with COPD. METHODS: A total of 13 people with COPD aged 45 to 85 years participated in the study. There was one measure designated for each of the five cognitive domains: Motor Speed was measured by the Finger Tapping Test; Perceptual Motor Speed and Sequencing was measured by the Connections Test; Inhibitory Processing was measured by the Stroop Color Test; Verbal Fluency was measured by the Controlled Oral Word Association Test (COWAT); and Psychomotor Performance was measured by the Digit Symbol Substitution Test. Seven correlation and five multiple regression hypotheses were designed to measure the relationships among the variables. RESULTS: Significance in age (hypothesis 1) was seen in three of the five cognitive domain measures: Connections Test Numbers Letters [-.570*, p< 0.05], Stroop Color [-.825**, p< 0.01], and Digit Symbol Substitution Test [-.792**, p< 0.01]. There were no significant relationships observed with depression (hypothesis 2) as measured by the Beck Depression Inventory; HRQL (hypothesis 3) as measured by the SIP-Overall; 6MWD (hypothesis 4); pulmonary function (hypothesis 6) as measured by FEV1 and 7DPAR-D (hypothesis 7) and the five cognitive domain measures. There was
an unexpected significant relationship observed regarding the vocabulary subtest and Stroop Color, however it was in the opposite direction than the recommended hypothesis 5 [-.576*, p< 0.05]. The multiple regressions were designed to identify the predictors among the specific cognitive domains. The models 1-5 included age, 6MWD, 7DPAR-D, SIP-Overall, and FEV1. The following multiple regression analyses were not supported: hypothesis 8 regarding Motor Speed; hypothesis 9 regarding Perceptual Motor Speed and Sequencing; and hypothesis 11 regarding Verbal Fluency. Hypothesis 12 regarding Psychomotor Performance was fully supported for models 1-4, primarily due to the strength of age, however, it was not strong enough for a significant 5th model.
Hypothesis 10 regarding Inhibitory Processing, however was supported among all of the models 1-5. CONCLUSION: One consistent feature noted within the results was the significant percentages of variation accounted for by age alone or with age and 6MWD, in the cognitive domains perceptual motor speed and sequencing, inhibitory processing, and psychomotor performance. The identified relationships are consistent with the literature except for the results from BDI and vocabulary subtest. The mechanisms for decreased cognition are multiple and the present study can be regarded as a springboard for future research in the area of COPD.