Adjustment disorder is primarily used to describe a disturbance that has directly risen from a psychosocial stresser. It has specific specifiers, and is coded as "adjustment disorder with depressed mood", or "with disturbance in conduct", or "mixed anxiety and depression," etc. If they meet criteria for another I disorder that accounts for the disturbance, it trumps the Adjustment DO diagnosis. There is not a psychotic specifier. Brief Psychotic disorder itself has a specifier of "with or without marked stressers." Florid psychosis is not something you generally see in reaction to a stresser, if that was the case the person likely had/has a preexisting underlying psychotic disorder. So, even in the case of an identifiable stresser and a month of psychotic symptomatology following that, the diagnosis of "Brief Psychotic disorder, With Marked Stressors" is most appropriate, not "Adjustment disorder."