Gas exchange and exercise capacity affect neurocognitive performance in patients with lung disease

Objective: This study examined the relationship between cognitive functioning and the severity of underlying lung disease in patients awaiting lung transplantation. Methods: Ninety-four patients with end-stage lung disease completed a test battery to assess cognitive performance in two domains: executive functioning/attention (Trails A and B, COWA, Animal Naming, Stroop Color-Word Test, Digit Symbol, and the 2 & 7 Test) and verbal memory (Digit Span-Backward and Forward, WMS-R Logical Memory and Paired Verbal Associates). Results: Thirty-seven percent of the patients demonstrated moderate to severe cognitive impairment data on two or more tests. Adjusting for age and education, there were no statistically significant differences on executive functioning or verbal memory as a function of specific lung disease diagnosis. Lower PCO ₂ values were associated with better cognitive performance on latent measures of executive functioning and attention (p = .006) and verbal memory (p = .009), whereas higher PO₂ values tended to be associated with better performance on the executive functioning/attention measure (p = .064). Distance walked in 6 minutes was positively related to verbal memory (p < .023). Conclusions: Impaired neurocognitive functioning may be relatively common in patients awaiting lung transplantation and is associated with ineffective pulmonary gas exchange and reduced exercise tolerance.