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Cannabis use and psychosis: a review of reviews


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.

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  1. 1.

    Barkus E, Lewis S (2008) Schizotypy and psychosis-like experiences from recreational cannabis in a non-clinical sample. Psychol Med 38:1267–1276

    CAS  PubMed  Google Scholar 

  2. 2.

    Gage SH, Hickman M, Zammit S (2016) Association between cannabis and psychosis: epidemiologic evidence. Biol Psychiatry 79:549–556

    PubMed  Google Scholar 

  3. 3.

    Martin-Santos R, Crippa JA, Batalla A et al (2012) Acute effects of a single, oral dose of d9-tetrahydrocannabinol (THC) and cannabidiol (CBD) administration in healthy volunteers. Curr Pharm Des 18:4966–4979

    CAS  PubMed  Google Scholar 

  4. 4.

    Mechoulam R, Hanus LO, Pertwee R et al (2014) Early phytocannabinoid chemistry to endocannabinoids and beyond. Nat Rev Neurosci 15:757–764

    CAS  PubMed  Google Scholar 

  5. 5.

    Gage SH, Zammit S, Hickman M (2013) Stronger evidence is needed before accepting that cannabis plays an important role in the aetiology of schizophrenia in the population. F1000 Med Rep 5:2

    PubMed  PubMed Central  Google Scholar 

  6. 6.

    Hill M (2015) Perspective: be clear about the real risks. Nature 525:S14

    CAS  PubMed  Google Scholar 

  7. 7.

    Ksir C, Hart CL (2016) Cannabis and psychosis: a critical overview of the relationship. Curr Psychiatry Rep 18:12

    PubMed  Google Scholar 

  8. 8.

    Minozzi S, Davoli M, Bargagli AM et al (2010) An overview of systematic reviews on cannabis and psychosis: discussing apparently conflicting results. Drug Alcohol Rev 29:304–317

    PubMed  Google Scholar 

  9. 9.

    Di Forti M, Quattrone D, Freeman TP et al (2019) The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case–control study. Lancet Psychiatry 6:427–436

    PubMed  Google Scholar 

  10. 10.

    Schoeler T, Monk A, Sami MB et al (2016) Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis. Lancet Psychiatry 3:215–225

    PubMed  Google Scholar 

  11. 11.

    Burns JK (2013) Pathways from cannabis to psychosis: a review of the evidence. Front Psychiatry 4:128

    PubMed  PubMed Central  Google Scholar 

  12. 12.

    D’souza DC, Sewell RA, Ranganathan M (2009) Cannabis and psychosis/schizophrenia: human studies. Eur Arch Psychiatry Clin Neurosci 259:413–431

    PubMed  PubMed Central  Google Scholar 

  13. 13.

    Bersani G, Orlandi V, Kotzalidis GD et al (2002) Cannabis and schizophrenia: impact on onset, course, psychopathology and outcomes. Eur Arch Psychiatry Clin Neurosci 252:86–92

    CAS  PubMed  Google Scholar 

  14. 14.

    Hartz SM, Pato CN, Medeiros H et al (2014) Comorbidity of severe psychotic disorders with measures of substance use. JAMA Psychiatry 71:248–254

    PubMed  PubMed Central  Google Scholar 

  15. 15.

    Radhakrishnan R, Wilkinson ST, D’souza DC (2014) Gone to pot—a review of the association between cannabis and psychosis. Front Psychiatry 5:54

    PubMed  PubMed Central  Google Scholar 

  16. 16.

    Falkai P, Rossner MJ, Schulze TG et al (2015) Kraepelin revisited: schizophrenia from degeneration to failed regeneration. Mol Psychiatry 20:671–676

    CAS  PubMed  Google Scholar 

  17. 17.

    Schmitt A, Malchow B, Hasan A et al (2014) The impact of environmental factors in severe psychiatric disorders. Front Neurosci 8:19

    PubMed  PubMed Central  Google Scholar 

  18. 18.

    Bastian H, Glasziou P, Chalmers I (2010) Seventy-five trials and eleven systematic reviews a day: how will we ever keep up? PLoS Med 7:e1000326

    PubMed  PubMed Central  Google Scholar 

  19. 19.

    Smith V, Devane D, Begley CM et al (2011) Methodology in conducting a systematic review of systematic reviews of healthcare interventions. BMC Med Res Methodol 11:15

    PubMed  PubMed Central  Google Scholar 

  20. 20.

    Hoch E, Friemel C, Schneider M (2018) Cannabis: Potenzial und Risiko. In: Hoch E, Friemel C, Schneider M (eds) Eine wissenschaftliche Bestandsaufnahme. Springer, Berlin

    Google Scholar 

  21. 21.

    Äzq (2013) Institut für Medizinisches Wissensmanagement, Ärztliches Zentrum für Qualität in der Medizin. In: “Manual Systematische Literaturrecherche für die Erstellung von Leitlinien”. 1. Auflage 2013. Verfügbar: DCZ:; AWMF:; ÄZQ:

  22. 22.

    Higgins JPT, Green S (2011) Cochrane handbook for systematic reviews of interventions Version 5.1.0. The Cochrane Collaboration, London

    Google Scholar 

  23. 23.

    Hall W, Hoch E, Lorenzetti V (2019) Cannabis use and mental health: risks and benefits. Eur Arch Psychiatry Clin Neurosci 269:1–3

    PubMed  Google Scholar 

  24. 24.

    Awmf (2012) German Association of the Scientific Medical Societies (AWMF). AWMF-Regelwerk “Leitlinien”. 1. Auflage. In: Standing Guidelines Commission. AWMF guidance manual and rules for guideline development sEEvAahwaola-rh (ed)

  25. 25.

    Ocebm (2011) Levels of evidence working group. In: Oxford Centre for Evidence-Based Medicine O (ed), 2nd edn

  26. 26.

    Moher D, Liberati A, Tetzlaff J et al (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 339:b2535

    PubMed  PubMed Central  Google Scholar 

  27. 27.

    Hemming K, Pinkney T, Futaba K et al (2013) A systematic review of systematic reviews and panoramic meta-analysis: staples versus sutures for surgical procedures. PLoS ONE 8:e75132

    CAS  PubMed  PubMed Central  Google Scholar 

  28. 28.

    Sign (2015) Scottisch intercollegiate guidelines network 50 methodology checklist. Edinburgh, UK

    Google Scholar 

  29. 29.

    Burns JK (2012) Cannabis use and duration of untreated psychosis: a systematic review and meta-analysis. Curr Pharm Des 18:5093–5104

    CAS  PubMed  Google Scholar 

  30. 30.

    Koskinen J, Lohonen J, Koponen H et al (2010) Rate of cannabis use disorders in clinical samples of patients with schizophrenia: a meta-analysis. Schizophr Bull 36:1115–1130

    PubMed  Google Scholar 

  31. 31.

    Kraan T, Velthorst E, Koenders L et al (2016) Cannabis use and transition to psychosis in individuals at ultra-high risk: review and meta-analysis. Psychol Med 46:673–681

    CAS  PubMed  Google Scholar 

  32. 32.

    Large M, Sharma S, Compton MT et al (2011) Cannabis use and earlier onset of psychosis: a systematic meta-analysis. Arch Gen Psychiatry 68:555–561

    PubMed  Google Scholar 

  33. 33.

    Linscott RJ, Van Os J (2013) An updated and conservative systematic review and meta-analysis of epidemiological evidence on psychotic experiences in children and adults: on the pathway from proneness to persistence to dimensional expression across mental disorders. Psychol Med 43:1133–1149

    CAS  PubMed  Google Scholar 

  34. 34.

    Marconi A, Di Forti M, Lewis CM et al (2016) Meta-analysis of the association between the level of cannabis use and risk of psychosis. Schizophr Bull 42:1262–1269

    PubMed  PubMed Central  Google Scholar 

  35. 35.

    Moore TH, Zammit S, Lingford-Hughes A et al (2007) Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review. Lancet 370:319–328

    PubMed  Google Scholar 

  36. 36.

    Myles H, Myles N, Large M (2016) Cannabis use in first episode psychosis: meta-analysis of prevalence, and the time course of initiation and continued use. Aust N Z J Psychiatry 50:208–219

    PubMed  Google Scholar 

  37. 37.

    Myles N, Newall H, Nielssen O et al (2012) The association between cannabis use and earlier age at onset of schizophrenia and other psychoses: meta-analysis of possible confounding factors. Curr Pharm Des 18:5055–5069

    CAS  PubMed  Google Scholar 

  38. 38.

    Potvin S, Sepehry AA, Stip E (2007) Meta-analysis of depressive symptoms in dual-diagnosis schizophrenia. Aust N Z J Psychiatry 41:792–799

    PubMed  Google Scholar 

  39. 39.

    Potvin S, Sepehry AA, Stip E (2006) A meta-analysis of negative symptoms in dual diagnosis schizophrenia. Psychol Med 36:431–440

    PubMed  Google Scholar 

  40. 40.

    Sara GE, Large MM, Matheson SL et al (2015) Stimulant use disorders in people with psychosis: a meta-analysis of rate and factors affecting variation. Aust N Z J Psychiatry 49:106–117

    PubMed  Google Scholar 

  41. 41.

    Semple DM, Mcintosh AM, Lawrie SM (2005) Cannabis as a risk factor for psychosis: systematic review. J Psychopharmacol 19:187–194

    PubMed  Google Scholar 

  42. 42.

    Szoke A, Galliot AM, Richard JR et al (2014) Association between cannabis use and schizotypal dimensions—a meta-analysis of cross-sectional studies. Psychiatry Res 219:58–66

    PubMed  Google Scholar 

  43. 43.

    Baldacchino A, Hughes Z, Kehoe M et al (2012) Cannabis psychosis: examining the evidence for a distinctive psychopathology in a systematic and narrative review. Am J Addict 21(Suppl 1):S88–S98

    PubMed  Google Scholar 

  44. 44.

    Ben Amar M, Potvin S (2007) Cannabis and psychosis: what is the link? J Psychoact Drugs 39:131–142

    Google Scholar 

  45. 45.

    Cookey J, Bernier D, Tibbo PG (2014) White matter changes in early phase schizophrenia and cannabis use: an update and systematic review of diffusion tensor imaging studies. Schizophr Res 156:137–142

    PubMed  Google Scholar 

  46. 46.

    Ferretjans R, Moreira FA, Teixeira AL et al (2012) The endocannabinoid system and its role in schizophrenia: a systematic review of the literature. Revista brasileira de psiquiatria 34(Suppl 2):S163–S177

    PubMed  Google Scholar 

  47. 47.

    Geoffroy PA, Etain B, Houenou J (2013) Gene × environment interactions in schizophrenia and bipolar disorder: evidence from neuroimaging. Front Psychiatry 4:136

    PubMed  PubMed Central  Google Scholar 

  48. 48.

    James A, James C, Thwaites T (2013) The brain effects of cannabis in healthy adolescents and in adolescents with schizophrenia: a systematic review. Psychiatry Res 214:181–189

    PubMed  Google Scholar 

  49. 49.

    Malchow B, Hasan A, Fusar-Poli P et al (2013) Cannabis abuse and brain morphology in schizophrenia: a review of the available evidence. Eur Arch Psychiatry Clin Neurosci 263:3–13

    PubMed  Google Scholar 

  50. 50.

    Rapp C, Bugra H, Riecher-Rossler A et al (2012) Effects of cannabis use on human brain structure in psychosis: a systematic review combining in vivo structural neuroimaging and post mortem studies. Curr Pharm Des 18:5070–5080

    CAS  PubMed  PubMed Central  Google Scholar 

  51. 51.

    Serafini G, Pompili M, Innamorati M et al (2012) Can cannabis increase the suicide risk in psychosis? A critical review. Curr Pharm Des 18:5165–5187

    CAS  PubMed  Google Scholar 

  52. 52.

    Vera U, Annarita T, Rocco P et al (2013) Cannabis and psychosis: a systematic review of genetic studies. Curr Psychiatry Rev 9:302–315

    Google Scholar 

  53. 53.

    Zammit S, Moore TH, Lingford-Hughes A et al (2008) Effects of cannabis use on outcomes of psychotic disorders: systematic review. Br J Psychiatry 193:357–363

    PubMed  Google Scholar 

  54. 54.

    Gage SH, Jones HJ, Burgess S et al (2017) Assessing causality in associations between cannabis use and schizophrenia risk: a two-sample Mendelian randomization study. Psychol Med 47:971–980

    CAS  PubMed  Google Scholar 

  55. 55.

    Buchanan RW, Kreyenbuhl J, Kelly DL et al (2010) The 2009 schizophrenia PORT psychopharmacological treatment recommendations and summary statements. Schizophr Bull 36:71–93

    PubMed  Google Scholar 

  56. 56.

    DGPPN (2019) S3-Leitlinie Schizophrenie 2019. Available online:

  57. 57.

    Galletly C, Castle D, Dark F et al (2016) Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for the management of schizophrenia and related disorders. Aust N Z J Psychiatry 50:410–472

    PubMed  Google Scholar 

  58. 58.

    Hasan A, Falkai P, Wobrock T et al (2015) World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of schizophrenia. Part 3: update 2015 management of special circumstances: depression, suicidality, substance use disorders and pregnancy and lactation. World J Biol Psychiatry 16:142–170

    PubMed  Google Scholar 

  59. 59.

    Colizzi M, Murray R (2018) Cannabis and psychosis: what do we know and what should we do? Br J Psychiatry 212:195–196

    PubMed  Google Scholar 

  60. 60.

    Ruther T, Bobes J, De Hert M et al (2014) EPA guidance on tobacco dependence and strategies for smoking cessation in people with mental illness. Eur Psychiatry 29:65–82

    CAS  PubMed  Google Scholar 

  61. 61.

    Nielsen SM, Toftdahl NG, Nordentoft M et al (2017) Association between alcohol, cannabis, and other illicit substance abuse and risk of developing schizophrenia: a nationwide population based register study. Psychol Med 47:1668–1677

    CAS  PubMed  Google Scholar 

  62. 62.

    Hjorthoj C, Albert N, Nordentoft M (2018) Association of substance use disorders with conversion from schizotypal disorder to schizophrenia. JAMA Psychiatry 75:733–739

    PubMed  PubMed Central  Google Scholar 

  63. 63.

    Pasman JA, Verweij KJH, Gerring Z, Stringer S, Sanchez-Roige S, Treur JL, Abdellaoui A, Nivard MG, Baselmans BML, Ong J-S, Ip HF, van der Zee MD, Bartels M, Day FR, Fontanillas P, Elson SL, de Wit H, Davis LK, MacKillop J, Derringer JL, Branje SJT, Hartman CA, Heath AC, van Lier PAC, Madden PAF, Maegi R, Meeus W, Montgomery GW, Oldehinkel AJ, Pausova Z, Ramos-Quiroga JA, Paus T, Ribases M, Kaprio J, Boks MPM, Bell JT, Spector TD, Gelernter J, Boomsma DI, Martin NG, MacGregor S, Perry JRB, Palmer AA, Posthuma D, Munafo MR, Gillespie NA, Derks EM, Vink JM (2018) GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal effect of schizophrenia liability. Nature Neuroscience 21(9):1161–1170

    CAS  PubMed  PubMed Central  Google Scholar 

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We acknowledge the contribution of Johannes Kabisch, Kathrin Schacherbauer, Luise Jacob, Sophia Schmieder, Udo Bonnet, Jan Copeland, Marica Ferri, Christopher Fowler, Winfried Häuser, Derik Hermann, Burkhard Hinz, Michael Höfler, Joseph Kambeitz, Ludwig Kraus, Beat Lutz, Frank Petzke, Liane Paul, Lukas Radbruch, Martin Storr, Michael Schäfer.


This paper was prepared in the context of the study “Cannabis: Potential and risks. A scientific analysis” (PIs: Dr. Eva Hoch, Dr. Miriam Schneider) funded by the German Ministry of Health. The funding sources had no influence on the design of the study or the analysis and interpretation of the results.

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Correspondence to Alkomiet Hasan.

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Conflict of interest

AH was an advisory board member of Janssen-Cliag, Otsuka, Lundbeck and Roche and he was a speaker for Janssen-Cliag, Otsuka and Lundbeck. FML is a shareholder of curantis UG (ltd.) and has received research grants from the German Federal Ministry of Education and Research and Acerus Pharmaceuticals. EH received research grants from the German Federal Ministry of Health and the European Monitoring Centre for Drugs and Drug Addiction. She receives fees for trainings and a treatment manual for cannabis use disorders. WS received speakers fees by Mag & More. All other authors did not report a conflict of interest. All other authors did not report any conflicts of interest related to the content of this article.

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Hasan, A., von Keller, R., Friemel, C.M. et al. Cannabis use and psychosis: a review of reviews. Eur Arch Psychiatry Clin Neurosci 270, 403–412 (2020).

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  • Psychosis
  • Schizophrenia
  • Cannabis
  • Cannabinoids
  • THC
  • CBD
  • Evidence-based medicine