A hospitalized patient develops sudden-onset confusion and agitation after surgery. What is the most likely diagnosis?

Rationale: A. Lewy body dementia is a chronic, progressive neurodegenerative disorder characterized by fluctuating cognition, visual hallucinations, and parkinsonism. Its onset is gradual, not sudden, and is not typically triggered acutely by surgery. B. Alzheimer’s disease is also a gradual, progressive cognitive decline. Acute confusion and agitation after surgery are not characteristic of Alzheimer’s, though pre-existing Alzheimer’s may increase susceptibility to delirium. C. Delirium is an acute, sudden-onset disturbance in attention, awareness, and cognition, often triggered by surgery, infection, medications, or metabolic disturbances. Postoperative patients, especially older adults, are at high risk. Hallmarks include confusion, agitation, fluctuating consciousness, and impaired focus, which aligns with the scenario described. This makes delirium the most likely diagnosis. D. Vascular dementia results from chronic cerebrovascular disease and typically presents with gradual cognitive decline and stepwise progression, not sudden acute confusion postoperatively.