Background: Hypoxemic patients with Chronic Obstructive Pulmonary Disease (COPD) have impaired cognitive performance. These neuropsychological impairments are related to the degree of hypoxemia. So far, cognitive performance has not been tested in non-hypoxemic patients with COPD.
Methods: We recruited patients with stable COPD and PaO2 > 8.0 kPa (60 mmHg), as well as healthy subjects, who were matched for age, intelligence quotient (IQ), and level of education. Cognitive performance was studied by Stroop Colour Word Test, Trailmaking, digit-symbol of the Wechsler Adult Intelligence Scale, addition subtest of the Groningen Intelligence Test, and Story Recall.
Results: Thirty patients with COPD (FEV1 49.8% pred, mean age 64.8 yr) and 20 healthy volunteers (65.6 yr) were enrolled. COPD patients performed significantly worse on trailmaking B, the digit-symbol test, and on the addition subtest. There was no significant correlation between the tests of cognitive performance and disease specific health status (Chronic Respiratory Questionnaire).
Conclusions: We conclude that even non-hypoxemic patients with COPD show significant impairments in cognitive performance. These impairments are not associated with deteriorations in health related quality of life. Prospective evaluation of the impact of treatment on cognitive performance in non-hypoxemic patients with COPD would be a logical subsequent study.