The increase in life expectancy has been accompanied by an escalation of age-related disease incidence. Mild cognitive impairment (MCI) is a decline of cognitive function higher than expected for a certain age, but not severe enough to meet the criteria for dementia. Hypoxemia, smoking history, ageing and several comorbidities are risk factors for both chronic respiratory diseases and cognitive deficit. Up to 70% of patients with chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA) or idiopathic pulmonary fibrosis (IPF) have a form of cognitive impairment. Furthermore, a low neuropsychological performance is an independent predictor of disability and mortality in these populations. Efficient tools for cognitive assessment have been validated for these patients and should be used for better clinical outcomes. The physiopathological mechanisms, clinical impact and prevention strategies for cognitive dysfunction in chronic respiratory diseases will be detailed in the following chapter.