Discontinuing cannabis after first psychosis improves functional long-term outcome and reduces negative symptoms, while continued use is associated with a worse course.
Summary
Prospective 8-year cohort (n=92) after first psychosis episode; patients who stopped cannabis (CUS, n=27) showed better functional long-term outcome vs. continuing users (CU, n=25): effect size=1.26 (95% CI 0.65-1.86) and fewer negative symptoms (effect size=-0.72, 95% CI -1.27 to -0.14). Cannabis cessation after first psychosis → clearly improved long-term course.
P
PopulationPatients with first-time psychosis hospitalisation, n=92; divided into: continuous cannabis users (CU, n=25), former cannabis users who stopped (CUS, n=27) and never-users (NU, n=40)
I
InterventionContinued cannabis use (CU) vs. discontinuation of cannabis use after first psychosis (CUS)
C
ControlPatients without cannabis use (NU) as well as comparison of CU vs. CUS with each other
O
OutcomeCUS group showed significantly better functional long-term outcome vs. CU and NU (effect size 1,26; 95%-CI 0,65–1,86) as well as fewer negative symptoms vs. CU (effect size −0,72; 95%-CI −1,27 to −0,14)
Confidence in the evidence
Very lowLowModerateHigh
Very low
The lowest GRADE level, the effect estimate remains uncertain.
Downgraded for
Imprecision
Quality profile
Sample size★★★★★
Blinding—
Effect sizeMixed
Citations / year★★★★★
Authors
González-Pinto A, Alberich S, Barbeito S, Gutierrez M, Vega P, Ibáñez B, Haidar MK, Vieta E, Arango C.
<h4>Objective</h4>To examine the influence of cannabis use on long-term outcome in patients with a first psychotic episode, comparing patients who have never used cannabis with (a) those who used cannabis before the first episode but stopped using it during follow-up and (b) those who used cannabis both before the first episode and during follow-up.<h4>Methods</h4>Patients were studied following their first admission for psychosis. They were interviewed at years 1, 3, and 5. At follow-up after 8 years, functional outcome and alcohol and drug abuse were recorded. Patients were classified according to cannabis use: 25 had cannabis use before their first psychotic episode and continuous use during follow-up (CU), 27 had cannabis use before their first episode but stopped its use during follow-up (CUS), and 40 never used cannabis (NU).<h4>Results</h4>The 3 groups did not differ significantly in symptoms or functional outcome at baseline or during short-term follow-up. The CUS group exhibited better long-term functional outcome compared with the other 2 groups and had fewer negative symptoms than the CU group, after adjusting for potential confounders. For the CUS group, the effect size was 1.26 (95% confidence interval [CI]=0.65 to 1.86) for functional outcome and -0.72 (95% CI=-1.27 to -0.14) for negative symptoms. All patients experienced improvements in positive symptoms during long-term follow-up.<h4>Conclusion</h4>Cannabis has a deleterious effect, but stopping use after the first psychotic episode contributes to a clear improvement in outcome. The positive effects of stopping cannabis use can be seen more clearly in the long term.