RFs: age > 65, male, impaired hearing or vision, prior hx delirium, dementia, hospitalization, surgery or serious illness, multiple meds, baseline dementia; Sx: acute change from prior behavior, including→ disorganized thinking, impaired short term memory, inattention, disorientation, confusion, delusions, hallucinations, altered sleep patterns; hypoactive (75%) or hyperactive (25%); Sx fluctuate; Spectrum from somnolent to very agitated; Typically reversible. Delirium is always secondary to something, including: