Delirium is a common, life-threatening, and potentially preventable clinical syndrome in older adults. It often leads to loss of independence, increased morbidity and mortality, and higher healthcare costs. Delirium affects up to 56% of hospitalized older patients and increases hospital costs by $2,500 per patient. Medicare expenditures related to delirium are estimated at $6.9 billion annually. Delirium is often unrecognized by healthcare providers due to its fluctuating nature and overlap with dementia. Delirium is an acute confusional state, distinct from dementia, and occurs in up to 83% of end-of-life patients. It is more common in hospitalized older adults and is associated with high mortality rates, up to 76% in hospitalized patients. The one-year mortality rate for delirium is 35-40%. Diagnosis is primarily clinical, based on bedside observation of key features. Delirium is often missed due to its fluctuating nature and lack of formal cognitive assessment. Delirium has hypoactive and hyperactive forms, with the hypoactive form being more common in older adults. It is caused by a complex interplay between a vulnerable patient and precipitating factors. The pathophysiology of delirium is not fully understood, but evidence suggests roles of cholinergic deficiency, dopaminergic excess, inflammation, and chronic stress. Cytokines and chronic stress can contribute to delirium by increasing blood-brain barrier permeability and altering neurotransmission. Prevention and management of delirium involve addressing multiple risk factors. Multicomponent interventions, such as early mobilization, minimizing psychoactive drugs, and improving sleep, are effective. Once delirium occurs, management includes addressing underlying causes, providing supportive care, and treating behavioral symptoms. Pharmacologic treatment is reserved for cases where symptoms threaten safety or interfere with essential therapies. Delirium and dementia are closely related, with dementia being a major risk factor for delirium. Delirium may contribute to worsening functional status and outcomes in patients with dementia. Delirium may also herald the onset of dementia in some cases. Delirium is a significant indicator of healthcare quality, as it is a common preventable adverse event in older patients. Preventing delirium can reduce healthcare costs and improve outcomes. New therapeutic approaches aim to increase acetylcholine activity, use selective dopamine antagonists, and enhance cerebrovascular flow. Delirium management is crucial for improving the quality of care for older patients.Delirium is a common, life-threatening, and potentially preventable clinical syndrome in older adults. It often leads to loss of independence, increased morbidity and mortality, and higher healthcare costs. Delirium affects up to 56% of hospitalized older patients and increases hospital costs by $2,500 per patient. Medicare expenditures related to delirium are estimated at $6.9 billion annually. Delirium is often unrecognized by healthcare providers due to its fluctuating nature and overlap with dementia. Delirium is an acute confusional state, distinct from dementia, and occurs in up to 83% of end-of-life patients. It is more common in hospitalized older adults and is associated with high mortality rates, up to 76% in hospitalized patients. The one-year mortality rate for delirium is 35-40%. Diagnosis is primarily clinical, based on bedside observation of key features. Delirium is often missed due to its fluctuating nature and lack of formal cognitive assessment. Delirium has hypoactive and hyperactive forms, with the hypoactive form being more common in older adults. It is caused by a complex interplay between a vulnerable patient and precipitating factors. The pathophysiology of delirium is not fully understood, but evidence suggests roles of cholinergic deficiency, dopaminergic excess, inflammation, and chronic stress. Cytokines and chronic stress can contribute to delirium by increasing blood-brain barrier permeability and altering neurotransmission. Prevention and management of delirium involve addressing multiple risk factors. Multicomponent interventions, such as early mobilization, minimizing psychoactive drugs, and improving sleep, are effective. Once delirium occurs, management includes addressing underlying causes, providing supportive care, and treating behavioral symptoms. Pharmacologic treatment is reserved for cases where symptoms threaten safety or interfere with essential therapies. Delirium and dementia are closely related, with dementia being a major risk factor for delirium. Delirium may contribute to worsening functional status and outcomes in patients with dementia. Delirium may also herald the onset of dementia in some cases. Delirium is a significant indicator of healthcare quality, as it is a common preventable adverse event in older patients. Preventing delirium can reduce healthcare costs and improve outcomes. New therapeutic approaches aim to increase acetylcholine activity, use selective dopamine antagonists, and enhance cerebrovascular flow. Delirium management is crucial for improving the quality of care for older patients.