Delirium is a common neuropsychiatric syndrome, especially in patients with preexistent cognitive impairment. Delirium is often precipitated by an acute infection, an operation, or an intensive care unit (ICU) stay and is associated with premorbid conditions, such as cerebral infarction, dementia, and genetic predisposition. The syndrome manifests itself in up to 50% of elderly hospitalized inpatients, with higher frequencies reported for ICU patients. Delirium is independently associated with increased mortality, impaired physical and cognitive recovery, and increased hospital costs. Although patients usually recover from delirium after resolution of the underlying condition, delirium seems to be an important risk factor for dementia, even in persons without prior cognitive impairment.1 Despite these adverse sequelae, the pathogenesis of delirium is still incompletely understood, although both stress hormones and proinflammatory cytokines have been shown to affect aspects of mental function, such as attention, memory, and perception.2,3