Differentiating first episode substance induced and primary psychotic disorders with concurrent substance use in young people.
OBJECTIVE
Substance use is common in first-episode psychosis, and complicates the accurate diagnosis and treatment of the disorder. The differentiation of substance-induced psychotic disorders (SIPD) from primary psychotic disorders (PPD) is particularly challenging. This cross-sectional study compares the clinical, substance use and functional characteristics of substance using first episode psychosis patients diagnosed with a SIPD and PPD.


METHODS
Participants were 61 young people (15-24 years) admitted to a psychiatric inpatient service with first episode psychosis, reporting substance use in the past month. Diagnosis was determined using the Psychiatric Research Interview for DSM-IV Substance and Mental disorders (PRISM-IV). Measures of clinical (severity of psychotic symptoms, level of insight, history of trauma), substance use (frequency/quantity, severity) and social and occupational functioning were also administered.


RESULTS
The PRISM-IV differentially diagnosed 56% of first episode patients with a SIPD and 44% with a PPD. Those with a SIPD had higher rates of substance use and disorders, higher levels of insight, were more likely to have a forensic and trauma history and had more severe hostility and anxious symptoms than those with a PPD. Logistic regression analysis indicated a family history of psychosis, trauma history and current cannabis dependence were the strongest predictors of a SIPD. Almost 80% of diagnostic predictions of a SIPD were accurate using this model.


CONCLUSIONS
This clinical profile of SIPD could help to facilitate the accurate diagnosis and treatment of SIPD versus PPD in young people with first episode psychosis admitted to an inpatient psychiatric service.
Psychological Sciences, Research Centre, University of Melbourne, Melbourne, VIC, 3010, Australia. samanthakatefraser@hotmail.uk
Samantha
S
Fraser
Leanne
L
Hides
Lisa
L
Philips
Dawn
D
Proctor
Dan I
DI
Lubman
D000293:Adolescent; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D011605:Psychoses, Substance-Induced / Q000175:diagnosis* / Q000453:epidemiology*; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D019966:Substance-Related Disorders / Q000453:epidemiology*; D055815:Young Adult