[Delirium in the elderly].

Delirium is a common, serious medical and often life-threatening condition in elderly in-patients. Delirium can develop primarily or secondarily related to other medical conditions and lead to hospital admission. The pathogenesis is still not fully known and is usually addressed as multifactorial. Alterations in neurotransmitters have a key role in this process. The incidence varies by setting up to 90%. Delirium is associated with increased short- and long-term mortality, iatrogenic complications, functional decline, and future development of cognitive impairment or dementia. Delirium is also associated with longer hospital stays, higher hospital and total health system costs, and an increasing rate of nursing home admissions. A structured diagnostic and therapeutic process is recommended. Delirium should become a quality indicator for hospital medicine; however, many research questions still exist.