An 86-year-old assisted living resident with previously intact cognition became confused over two days, with attention that comes and goes and new picking at her bedclothes. She started treatment for a urinary tract infection three days ago. This picture is MOST consistent with
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Answer: C
dementia with Lewy bodies.: Lewy body dementia also fluctuates, but it develops gradually, not over two days in someone with intact cognition.
late-onset depression.: Depression does not cause abrupt inattention and picking behavior.
delirium.: Correct. Acute onset over days, fluctuating attention and a likely medical trigger (infection, new medication) are the hallmarks of delirium, a medical problem needing prompt evaluation.
rapid progression of Alzheimer's disease.: She had no prior cognitive impairment, and Alzheimer's disease progresses gradually.
Sudden onset plus fluctuating attention means delirium until proven otherwise; dementia is gradual.