(E) HIV-related psychiatric disorder.
(D) Mental disorder due to a medical condition.
A 53-year-old male presents to the emergency room accompanied by a family friend who states that for approximately the last two hours the man has been acting "spaced out and strange." The history reveals that this man has no personal or family history of mental disorders and that his symptoms have occurred on a daily basis over the past several weeks, that they occurred for the first time "out of the blue," and that the symptoms "come and go" in the course of a typical day. Upon examination the man appears to be in no apparent distress, but his speech is obviously rambling and at times it is incoherent. His attention wanders, he periodically nods off during the short interview, and the man seems to be responding to visual stimuli. He is agitated and reports that he has had little sleep during the past several weeks and that he attributes his condition to this fact. There is no indication that substance use is involved, and the only significant laboratory finding is that of a thiamin deficiency. The most likely diagnosis for this man, given this information, is:
Question 4 of 40