An 80-year-old man is admitted to the intensive care unit for lobar pneumonia. Two days later, he suddenly becomes agitated and confused. His medical history is significant for a mild neurocognitive disorder, hypertension, and chronic low back pain. He lives with his son and can perform his activities of daily living with minimal assistance. Vital signs are temperature 98.6° F (37° C), blood pressure 125/90 mm Hg, heart rate 77 beats per minute, and oxygen saturation 98
1) Delirium
2) Dementia
3) Depression
4) Anxiety