In order to characterize the neuropsychologic profile of patients with hypoxic-hypercapnic chronic obstructive pulmonary disease (COPD), the performance of 36 patients with COPD 69 +/- 10 yr of age (mean +/- SD) on 19 tests exploring eight cognitive domains was compared with those of 29 normal adults (69 +/- 7 yr of age), 20 normal elderly adults (78 +/- 2 yr of age), 26 patients with Alzheimer-type dementia (72 +/- 6 yr of age), and 28 with multi-infarct dementia (MID) (70 +/- 8 yr of age). The discriminant analysis of cognitive test scores showed that 48.5% of patients with COPD had a specific pattern of cognitive deterioration characterized by a dramatic impairment in verbal and verbal memory tasks, well-preserved visual attention, and diffuse worsening of the other functions. The remaining patients with COPD were functionally classified as normal adults (12.1%), normal elderly adults (15.2%), those with MID (12.1%), and those with Alzheimer-type dementia (12.1%) according to discriminant analysis. Cognitive impairment was significantly and positively correlated with age (p < 0.05) and duration of hypoxic-hypercapnic chronic respiratory failure (p < 0.05). Because patients with COPD were receiving oxygen therapy from the beginning of oxyhemoglobin desaturation, results suggest that continuous oxygen therapy does not prevent or only partly prevents cognitive decline in COPD. Although some analogies between age-related and COPD-related cognitive decline are evident, a distinct cognitive profile was found in a large fraction of patients with COPD and it differs in several aspects from those of both normal and demented subjects.