[Delirium or acute confusional state in elderly persons].

Delirium or acute confusional state is a common neuropsychiatric syndrome in later life. Failure to recognise delirium and treat the underlying organic condition may have fatal consequences. In delirium the main aspects of cognition, thinking, perception and memory are all disordered to some degree. A global disorder of attention is invariably present and may include illusions and hallucinations. Disturbances in the sleep-wake cycle and abnormalities of the psychomotor activity are essential features. Hypoactive and hyperactive states are reported. Some patients have a mixed picture, with swing back and forth between apathy and agitation. Its onset is acute and its duration is brief (less than one month). Typically, the severity of the symptoms fluctuates during the daytime with peaks at night. The adequate treatment of delirium presupposes that the syndrome has been diagnosed and that its underlying causes have been identified.