[Respiratory sleep disorders in the elderly].

Ageing is often associated with a decrease in the quality of sleep. In older subjects, sleep-related breathing disorders (SRBD) are increasingly recognized as being responsible for alterations in the quality of sleep. The prevalence of obstructive sleep apnea (OSA) increases with ageing; despite sometimes major disturbances in sleep structure, clinical symptoms are often subtle in this age group. Central apnea and periodic breathing, also more frequent in older subjects, most often occur in patients suffering either from neurological problems (such as tumors, brain infarcts, sequelae of infection, diffuse encephalopathies) or moderate to severe heart failure. In fact, patients suffering from cerebro-vascular diseases (such as brain infarcts or transient ischemic attacks) have a higher prevalence of SRBD than a control age-matched population. In these patients, SRBD are associated with a poorer prognosis in terms of functional recovery and survival. The clinical impact of SRBD on cognitive function appears to be modest in patients without dementia, albeit for a slight increase in daytime somnolence. However, in patients suffering from Alzheimer's disease, SRBD occur more frequently than in non-demented subjects, and indexes of severity of SRBD have been correlated with the importance of cognitive impairment. The hypothesis of a causal relationship between SRBD and the degree neuropsychological impairment in either Alzheimer's disease or multi-infarct dementia remains a matter of controversy. SRBD should be considered as a possible cause of "reversible dementia" and sought for in the presence of daytime somnolence, delirium, or unexplained right-sided heart failure in older patients.