Substance use in clinical high risk for psychosis: a review of the literature.
OBJECTIVE
In the literature, there is evidence suggesting an association between substance use and psychosis. However, little is known about substance use in those who may be in the pre-psychotic phase, that is, those who are putatively prodromal are considered to be at clinical high risk (CHR) of developing psychosis.


METHODS
We conducted a review of publications measuring patterns and rates of substance use in CHR for psychosis individuals and the effects on the transition to psychosis.


RESULTS
Of 5527 potentially relevant research papers, 10 met inclusion criteria of CHR subjects and specifically mentioned substance use in the sample. The results of these studies varied. Cannabis, alcohol and tobacco/nicotine were reported as the most commonly used substances. There was limited information on the changes in patterns of use over time. Two out of the ten studies found a significant association between the use of substances and subsequent transition to psychosis. In one of these studies, substance abuse was a predictor of psychosis when included as a variable in a prediction algorithm. In the other study, the abuse of cannabis and nicotine was associated with transition to psychosis.


CONCLUSIONS
We found limited evidence to suggest that increased rates of substance use may be associated with transition to psychosis. However, further prospective research examining the association between substance use and transition to psychosis is required before any firm conclusions can be made.
Hotchkiss Brain Institute, Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada.
Jean
J
Addington
Nevicia
N
Case
Majid M
MM
Saleem
Andrea M
AM
Auther
Barbara A
BA
Cornblatt
Kristin S
KS
Cadenhead
D055030:Drug Users / Q000523:psychology*; D006801:Humans; D015995:Prevalence; D062706:Prodromal Symptoms; D011618:Psychotic Disorders / Q000150:complications* / Q000453:epidemiology / Q000523:psychology*; D019966:Substance-Related Disorders / Q000150:complications* / Q000453:epidemiology / Q000523:psychology*
cannabis; clinical high risk; psychosis; review; substance use