Delirium is a fluctuating syndrome characterized by inattention, altered level of consciousness and acute global cognitive impairment. There are three forms of delirium, hypoactive, hyperactive and mixed forms, which fluctuate between the hyperactive and hypoactive phases. The mixed forms account for 52% of cases, highlighting the fluctuating course of a delirium. The incidence of postoperative delirium in older patients is estimated between 20 and 50%. Moreover, among older patients admitted to an intensive care unit (ICU), the incidence can reach 70 to 87%. Delirium is associated with a significant increase in morbidity and mortality, a higher risk of admission to a long-term care facility and higher healthcare costs. Although delirium can be reversed through the treatment of its underlying causes, many patients do not return to their baseline cognitive level. In addition, in patients with dementia, cognitive decline may be accelerated. Despite its clinical significance, postoper...