←Psychosis Risk
Study register · detail Meta-Analyse · Psychosis Risk · 2020

Cannabis use and psychosis: a review of reviews.

Hasan et al. ·European archives of psychiatry and clinical neuroscience Impact 2.9
Clear benefit GRADE High 248 citations
Samplek = 26 Studien
DurationLiterature search 2005-2016
ControlNon-cannabis users
EndpointPsychosis incidence/course
Blindingunklar
DesignMeta-Analyse
Key finding

Cannabis use is associated with increased risk of psychosis onset, dose-dependent risk, earlier manifestation and, in existing psychosis, with more relapses, hospitalisations and stronger positive symptoms.

Summary

Umbrella review of k=26 systematic reviews and meta-analyses on cannabis and psychosis (2005-2016). Psychotic disorders occur more frequently in cannabis users; dose-dependent risk for psychotic disorders; earlier disease onset in cannabis users; increased relapse rates, more hospitalisations and more pronounced positive symptoms in psychotic patients with cannabis use.

P
PopulationPersons with cannabis use or risk for psychoses or existing psychoses – pooled data from 26 systematic reviews/meta-analyses
I
InterventionCannabis use (various consumption patterns and intensities)
C
ControlNon-cannabis users
O
OutcomeIncreased psychosis risk in users; dose-dependent risk increase; earlier disease onset; increased relapse rates, more hospitalisations and more pronounced positive symptoms in existing psychoses
Confidence in the evidence
High

The highest of four GRADE levels, the effect estimate is very reliable.

Quality profile
Sample size ★★★★★
Blinding —
Effect size Clear benefit
Citations / year ★★★★★
Authors
Hasan A, von Keller R, Friemel CM, Hall W, Schneider M, Koethe D, Leweke FM, Strube W, Hoch E
DOI 10.1007/s00406-019-01068-z↗
Design: Meta-Analyse
Share
Abstract
We conducted a systematic review of meta-analyses and systematic reviews to evaluate the impact of cannabis use on the onset and course of psychoses. Following a systematic literature search of five data bases (2005-2016) and consecutive structured evaluation, we were able to include 26 systematic reviews and meta-analyses. The methodological quality of the included publications were in the range of high and poor. The scientific literature indicates that psychotic illness arises more frequently in cannabis users compared to non-users, cannabis use is associated with a dose-dependent risk of developing psychotic illness, and cannabis users have an earlier onset of psychotic illness compared to non-users. Cannabis use was also associated with increased relapse rates, more hospitalizations and pronounced positive symptoms in psychotic patients. We make recommendations about the type of research that is required to better characterize the relationship between cannabis use and the development and outcomes of psychosis.
Indication
Further studies on Psychosis Risk
All studies →
S Marconi et al. · 2016 · Schizophrenia Bulletin
860 citations
Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis
Clear benefit Meta-Analyse

Meta-Analyse über 10 Studien (n≈66.816) zur Dosis-Wirkungs-Beziehung zwischen Cannabis-Konsum und Psychose-Risiko; OR=3.90 (95% CI 2.84–5.34) für täglichen vs. Nicht-Konsum, OR=1.97 (1.68–2.31) für jeglichen Konsum vs. Nie-Konsum; klare Evidenz für erhöhtes Psychose-Risiko bei stärkerem Cannabis-Gebrauch.

10.1093/schbul/sbw003 View study →
S Andréasson et al. · 1987 · The Lancet
1144 citations
Cannabis and schizophrenia. A longitudinal study of Swedish conscripts.
Harm Prospektive Kohortenstudie

Landmark-Kohortenstudie (n=45.570 schwedische Wehrpflichtige, 15 Jahre Follow-up); Hochkonsumenten (>50 Gelegenheiten) RR=6,0 (95%-KI 4,0–8,9) für Schizophrenie; Dosis-Wirkungs-Gradient; Cannabis als unabhängiger Schizophrenie-Risikofaktor nach multivariater Adjustierung bestätigt.

10.1016/s0140-6736(87)92620-1 View study →
S Di Forti et al. · 2019 · The Lancet Psychiatry
844 citations
The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study
Harm Multizentrisches Fall-Kontroll-Studie

Multizentrische EU-GEI Fall-Kontroll-Studie (n=901 Fälle, n=1237 Kontrollen, 11 europäische Standorte): täglicher Cannabiskonsum OR=3,2 (95%-KI 2,2–4,1) für psychotische Störung; täglicher Hochpotenz-Cannabis OR=4,8 (95%-KI 2,5–6,3). Populationsattributabler Anteil (PAF) für Hochpotenz-Cannabis: 12,2% gesamt, 30,3% in London, 50,3% in Amsterdam. Inzidenzrate korrelierte positiv mit Hochpotenz-Prävalenz (r=0,7; p=0,0286) und täglichem Konsum (r=0,8; p=0,0109).

10.1016/s2215-0366(19)30048-3 View study →

The impediment to action advances action. — Marcus Aurelius