Delirium vs Dementia

A 68-year-old man with a 3-year history of progressive memory loss and cognitive decline is brought to the hospital by his family. He has been increasingly forgetful, disoriented to time, and unable to perform activities of daily living. His mental status has been relatively stable over the past 6 months. Vital signs are normal, and physical examination reveals no focal neurological deficits. Which investigation is most appropriate to confirm the underlying diagnosis and exclude reversible causes?

A 72-year-old woman is admitted to the hospital with acute onset confusion, disorientation, and visual hallucinations over the past 12 hours. She was previously independent and cognitively intact. On examination, she is agitated, her attention is poor, and she has fluctuating consciousness. Temperature is 38.5°C, heart rate 110/min. Urine dipstick shows leukocyte esterase and nitrites. Which investigation is most appropriate to establish the diagnosis?

A 68-year-old man with a 3-year history of progressive memory loss and cognitive decline is brought to the psychiatric outpatient clinic by his daughter. He has been increasingly forgetful, with difficulty recognizing family members and managing finances. His vital signs are stable, and he has no fever or acute illness. What is the most common cause of dementia in this clinical presentation?

A 72-year-old woman with hypertension and diabetes mellitus is admitted to the hospital with acute-onset confusion, disorientation, and agitation that developed over 6 hours. She has a fever of 38.5°C, tachycardia, and a urinary catheter in place for 3 days. Her mini-mental state examination score is 18/30. What is the most common cause of delirium in this hospitalized elderly patient?

A 72-year-old woman with Alzheimer's dementia is admitted to the hospital for pneumonia. Over the past 24 hours, she has become increasingly agitated, disoriented to time and place, and her family reports her confusion worsens in the evening and improves in the morning. Her vital signs show fever (38.5°C) and tachycardia. Which of the following is NOT consistent with superimposed delirium in this patient?