Subclinical encephalopathy in chronic obstructive pulmonary disease.

BACKGROUND Clinical and experimental evidence suggests that chronic obstructive pulmonary disease (COPD) is associated with a variety of mental symptoms that range from cognitive slowing to mental confusion and dementia. PURPOSE To test the hypothesis that COPD leads to cognitive impairment in the absence of acute confusion or dementia. METHOD The global cognitive status of 30 patients with COPD without dementia or acute confusion and 34 controls was assessed with a Brazilian version of the Mini-Mental State Exam (MMSE). RESULTS The MMSE scores were significantly lower in the patient group and inversely related to the severity of COPD. This finding could not be attributed to age, education, gender, daytime sleepiness, hypoxemia, chronic tobacco use, or associated diseases such as diabetes, depression, high blood pressure or alcoholism. CONCLUSION These results suggest the existence of a subclinical encephalopathy of COPD characterized by a subtle impairment of global cognitive ability.