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Cited by 470Cannabis and Cannabinoid ResearchSchizophrenia research and treatmentSubstance Abuse Treatment and Outcomes

Daily Use, Especially of High-Potency Cannabis, Drives the Earlier Onset of Psychosis in Cannabis Users

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Di Forti, M., Sallis, H., Allegri, F., Trotta, A., Ferraro, L., Stilo, S. A., Marconi, A., La Cascia, C. +14 more·2014·Schizophrenia Bulletin
DOI 10.1093/schbul/sbt181PMC PMC4193693
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Abstract

UNLABELLED: Cannabis use is associated with an earlier age of onset of psychosis (AOP). However, the reasons for this remain debated. METHODS: We applied a Cox proportional hazards model to 410 first-episode psychosis patients to investigate the association between gender, patterns of cannabis use, and AOP. RESULTS: Patients with a history of cannabis use presented with their first episode of psychosis at a younger age (mean years = 28.2, SD = 8.0; median years = 27.1) than those who never used cannabis (mean years = 31.4, SD = 9.9; median years = 30.0; hazard ratio [HR] = 1.42; 95% CI: 1.16-1.74; P < .001). This association remained significant after controlling for gender (HR = 1.39; 95% CI: 1.11-1.68; P < .001). Those who had started cannabis at age 15 or younger had an earlier onset of psychosis (mean years = 27.0, SD = 6.2; median years = 26.9) than those who had started after 15 years (mean years = 29.1, SD = 8.5; median years = 27.8; HR = 1.40; 95% CI: 1.06-1.84; P = .050). Importantly, subjects who had been using high-potency cannabis (skunk-type) every day had the earliest onset (mean years = 25.2, SD = 6.3; median years = 24.6) compared to never users among all the groups tested (HR = 1.99; 95% CI: 1.50- 2.65; P < .0001); these daily users of high-potency cannabis had an onset an average of 6 years earlier than that of non-cannabis users. CONCLUSIONS: Daily use, especially of high-potency cannabis, drives the earlier onset of psychosis in cannabis users.

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Authors
Di Forti, M., Sallis, H., Allegri, F., Trotta, A., Ferraro, L., Stilo, S. A., Marconi, A., La Cascia, C., Reis Marques, T., Pariante, C., Dazzan, P., Mondelli, V., Paparelli, A., Kolliakou, A., Prata, D., Gaughran, F., David, A. S., Morgan, C., Stahl, D., Khondoker, M., MacCabe, J. H., & Murray, R. M.
Affiliations
  • University of Bristol (GB)
  • University of Bologna (IT)
  • King's College London (GB)
  • University of Palermo (IT)
ORCID
Venue
Schizophrenia Bulletin
Publisher
Oxford University Press (OUP)
Published
2013-12-17
Volume
40
Issue
6
Pages
1509-1517
ISSN
  • 0586-7614 (ISSN-L)
  • 1745-1701
DOI
10.1093/schbul/sbt181
PMC
PMC4193693
OpenAlex
W2139701553
Cited by
470
References
3
Citations by year
2026: 10 · 2025: 30 · 2024: 35 · 2023: 40 · 2022: 44 · 2021: 33 · 2020: 50 · 2019: 29 · 2018: 47 · 2017: 52 · 2016: 40 · 2015: 44 · 2014: 16
FWCI
24.52
Type
journal article
Language
en
Open access
Locations
  • Schizophrenia Bulletin (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Research Portal (King's College London) (publishedVersion, other-oa)
  • Nova Science Publishers (Nova Science Publishers, Inc.) (submittedVersion, other-oa)
  • UCL Discovery (University College London) (submittedVersion)
  • Bristol Research (University of Bristol) (submittedVersion)
  • UEA Digital Repository (University of East Anglia) (submittedVersion)
Funders
  • Maudsley Charity
  • Psychiatry Research Trust
  • National Institute for Health and Care Research (CL-2012-17-004, PDF-2010-03-047)
  • Academy of Medical Sciences (AMS-SGCL5-Mondelli)
  • King's College London
  • European Commission (241909)
Topics
  • Health Sciences › Medicine › Pharmacology › Cannabis and Cannabinoid Research
  • Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
  • Health Sciences › Medicine › Epidemiology › Substance Abuse Treatment and Outcomes
Keywords
cannabis use, transition to psychosis
MeSH terms
Adult, Affective Disorders, Psychotic, Cannabis, Female, Humans, Male, Psychotic Disorders, Risk, Sex Factors, Age of Onset

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