INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .
Course of cannabis use and clinical outcome in patients with non-affective psychosis: a 3-year follow-up study.
BACKGROUND Prospect i ve studies on the relationship between course of cannabis use and clinical outcome in patients with non-affective psychotic disorders are inconclusive . The current study examined whether ( 1 ) persistent , recently started , discontinued and non-cannabis-using patients with a psychotic disorder differed with regard to illness outcome at 3-year follow-up , and ( 2 ) whether timing of cannabis discontinuation was associated with course of clinical outcome . METHOD This 3-year follow-up study was part of a multi-center study in the Netherl and s and Belgium ( Genetic Risk and Outcome of Psychosis ; GROUP ) . We used mixed-model analyses to investigate the association between pattern of cannabis use and symptoms , global functioning and psychotic relapse . RESULTS In our sample of 678 patients , we found persistent users to have more positive and general symptoms , worse global functioning and more psychotic relapses compared with non-users and discontinued users [ Positive and Negative Syndrome Scale ( PANSS ) positive , p < 0.001 ; PANSS general , p < 0.001 ; Global Assessment of Functioning ( GAF ) symptoms , p = 0.017 ; GAF disability , p < 0.001 ; relapses , p = 0.038 ] . Patients who started using cannabis after study onset were characterized by worse functioning at baseline and showed an increase in general symptoms ( including depression and anxiety ) at the 3-year follow-up ( p = 0.005 ) . Timing of cannabis discontinuation was not associated with clinical outcome . CONCLUSIONS These findings suggest that cannabis use in patients with a psychotic disorder has a long-lasting negative effect on illness outcome , particularly when persistent . Treatment should focus on discouraging cannabis use
INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .