Delirium is an acute, fluctuating disturbance in attention, awareness, and cognition not better explained by a pre-existing neurocognitive disorder. It affects 15-50% of hospitalized elderly patients and is independently associated with increased mortality (10-65% in-hospital mortality), longer hospitalization (average 5-10 additional days), accelerated cognitive decline, and increased institutionalization. Three subtypes exist: hyperactive (agitation, hallucinations, restlessness — 25%), hypoactive (lethargy, withdrawal, decreased responsiveness — 50%, often missed), and mixed (fluctuating between hyper and hypoactive — 25%). The Confusion Assessment Method (CAM) is the gold standard bedside screening tool with four features: (1) acute onset and fluctuating course (required), (2) inattention (required — patient cannot recite months backward or serial 7s), (3) disorganized thinking, AND/OR (4) altered level of consciousness. Positive CAM requires features 1 AND 2 PLUS either 3 OR 4. Delirium is a medical EMERGENCY requiring identification and treatment of the underlying cause. Common precipitants follow the DELIRIUM mnemonic: Drugs (anticholinergics, benzodiazepines, opioids), Electrolyte imbalances, Lack of drugs (withdrawal), Infection (UTI, pneumonia), Reduced sensory input, Intracranial event (stroke, bleed), Urinary retention/fecal impaction, Metabolic (hypoglycemia, hepatic encephalopathy). Prevention through the Hospital...