Clinical characteristics of primary psychotic disorders with concurrent substance abuse and substance-induced psychotic disorders: A systematic review.

BACKGROUND: Distinguishing between a primary psychotic disorder with concurrent substance abuse (PPD+SA) and a substance-induced psychotic disorder (SIPD) can be diagnostically challenging. We aimed to determine if these two diagnoses are clinically distinct, particularly in relation to psychopathology. In addition, we aimed to examine the specific clinical features of cannabis-induced psychotic disorder (CIPD) as compared to primary psychotic disorder with concurrent cannabis abuse (PPD+CA) and also to SIPD associated with any substance.

METHODS: A systematic review of SIPD literature using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS: Using strict inclusion criteria, a total of six studies examining SIPD were included in the review (two of which only considered psychosis induced by cannabis alone). The findings did not reveal many consistent differences in psychopathology. However, we did find that that compared to PPD+SA, individuals with SIPD have a weaker family history of psychotic disorder; a greater degree of insight; fewer positive symptoms and fewer negative symptoms; more depression (only in CIPD) and more anxiety.

CONCLUSION: There remains a striking paucity of information on the psychopathology, clinical characteristics and outcome of SIPD. Our review highlights the need for further research in this area.