Nine COPD patients were screened from the Respiration Laboratory (RespLab) of Federal University of Ceará, and twelve sedentary controls from the general population were also assessed. All patients were under stable medical treatment at least two months, and COPD diagnosis was made according to GOLD guidelines. Patients were excluded if they had heart disease, arterial hypertension, other debilitating pulmonary or non-pulmonary diseases, depression, preexisting psychiatric or neurologic disorders, stroke, motor impairment, visual or hearing disabilities, mini-mental scale examination score below 20 points, and any disease that could influence the effectiveness of NIV application or the performance of cognitive tests. The control group consisted of healthy and nonsmoking volunteers.