Jul 6, 2011
Big Apple, USA
How can you tell the difference between the two? They both seem to be characterized by similar symptoms (disorganized thought, hallucinations, delusions, distortion of reality, etc.) Is it just based on context? For example, if a previously normal elderly patient suddenly gets belligerent in the hospital do we just assume delirium instead of psychosis?
Jun 14, 2010
History is key. Also for schizo (of which brief psycho disorder is a type) you have auditory hallucinations but for del you have visual hallucinations.


10+ Year Member
7+ Year Member
Mar 27, 2008
I would say watch the timing too. A brief psychotic episode lasts <1 month but I don't think you can have a prolonged period of delirium for a month. Obviously they both start sometime but its something to consider.

Also look for a psychological stressor in brief psychotic disorder, whereas delirium I would look for drugs/illness.


7+ Year Member
May 5, 2009
Rochester, NY
Resident [Any Field]
As lemonade pointed out, history will be given that suggests this. For delirium, signs of systemic illness such as fever, electrolyte imbalance, and the like will be present. Urosepsis in the elderly is a notorious example. The context of substance withdrawal, or post-op period may be used. Odds are patient will be elderly, possibly on anticholinergics, and this will be in the hospital setting. The boards like to paint stereotypical pictures, so there'll be hints along the way. Impaired consciousness (unlike dementia or psychotic episode), autonomic dysfunction and other signs of outright physical illness, symptom exacerbation at night (sun-downing) will likely be present. It's unlikely you'll be given a question with no crutches at all, where you may as well flip a coin. :)


10+ Year Member
Feb 11, 2008
Resident [Any Field]
Something else I have noticed (from practice Q's and from clinical experience) is that delirium is more likely to be a sudden onset and could also include the patient being uncooperative or combative.


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7+ Year Member
Jan 17, 2012
Osaka, Japan
As AndyRSC has pointed out, delirium always has an organic aetiology associated with it (e.g. illness/fever, drugs, electrolyte imbalance). Treat the aetiology.

Brief psychotic disorder can appear like acute stress disorder in that it can occur following a distressing incident (e.g. watching a parent die in a robbery), except the patient is notably psychotic, as opposed to just demonstrating occupational/social effects or re-dramatization. It's usually self-limiting, although prognosis is worse if negative symptoms appear.