We think we know what a “delirious” patient looks like in the hospital–yelling, throwing things at people, completely alert and dis-oriented x3.
There is the perception that delirium is either completely obtunded or completely manic. In reality, delirium can look like anything between! A delirious person may be able to have a perfectly logical conversation with you until they look outside at the snow on the ground and say, “What a beautiful summer we’re having!”
The critical question to ask is: is cognition impaired? If cognition is impaired, then make a differential based on that. If cognition is NOT impaired, then it may in fact be a psychiatric process at play. For instance, a schizophrenic might have a 30/30 MMSE but will “act crazy”…that’s not delirium. That’s schizophrenia.