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. 2008 Jul 16:(3):CD004837.
doi: 10.1002/14651858.CD004837.pub2.

Cannabis and schizophrenia

John Rathbone  1 , Hannele Variend, Hetal Mehta
Affiliations

Cannabis and schizophrenia

John Rathbone et al. Cochrane Database Syst Rev. .

Update in

  • Cannabis and schizophrenia.
    McLoughlin BC, Pushpa-Rajah JA, Gillies D, Rathbone J, Variend H, Kalakouti E, Kyprianou K. McLoughlin BC, et al. Cochrane Database Syst Rev. 2014 Oct 14;2014(10):CD004837. doi: 10.1002/14651858.CD004837.pub3. Cochrane Database Syst Rev. 2014. PMID: 25314586 Free PMC article.

Abstract

Background: Many people with schizophrenia use cannabis and its effects on the illness are unclear.

Objectives: To evaluate the effects of cannabis use on people with schizophrenia and schizophrenia-like illnesses.

Search strategy: We searched the Cochrane Schizophrenia Group Trials Register (April 2007) which is based on regular searches of BIOSIS, CENTRAL, CINAHL, EMBASE, MEDLINE and PsycINFO.

Selection criteria: We included all randomised trials involving cannabinoids and people with schizophrenia or schizophrenia-like illnesses.

Data collection and analysis: We extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis, based on a fixed effects model. We calculated the numbers needed to treat/harm (NNT/NNH). For continuous data, we calculated weighted mean differences (WMD) again based on a fixed effects model.

Main results: We identified one randomised trial. No significant differences were found between the Cannabis and Psychosis Therapy (CAP) intervention group and the Psychoeducaton (PE) intervention for use of cannabis at three months assessment (n=47, RR 1.04 CI 0.6 to 1.7). BPRS-extended scale scores at three months assessment (n=47, WMD -3.60 CI -12.8 to 5.6) and nine months assessment (n=47, WMD 0.80 CI -7.5 to 9.1) were non-significant between CAP and PE. We found no significant improvement in social functioning in the CAP group compared with PE (at 3 months, n=47, WMD -0.80 CI -10 to 8.4) and (at 9 months, n=47, WMD -4.70 CI -14.5 to 5.1).

Authors' conclusions: At present, there is insufficient evidence to support or refute the use of cannabis/cannabinoid compounds for people suffering with schizophrenia. This review highlights the need for well designed, conducted and reported clinical trials to address the potential effects of cannabis based compounds for people with schizophrenia.

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Figures

Figure 1
Figure 1
Cannabis sativa
Figure 2
Figure 2
delta-9-tetrahydrocannabinol (THC)
See this image and copyright information in PMC

References

References to studies included in this review

    1. Edwards J. Early psychosis service developments: becoming real. 3rd International Conference on Early Psychosis; Copenhagen, Denmark. 2002 Sep 25-28; 2002. [: KA03]
    2. Edwards J, Elkins K, Hinton M, Harrigan SM, Donovan K, Athanasopoulos O, McGorry PD. Randomized controlled trial of a cannabis-focused intervention for young people with first-episode psychosis. Acta Psychiatrica Scandinavica. 2006;114(2):109–17. [MEDLINE: 16836598] - PubMed
    3. Edwards J, Elkins KS, Hinton MF, Harrigan SM, Donovan KD, Athanasopoulos O. Randomized controlled trial of a cannabis-focused intervention versus psychoeducation for young people continuing to use cannabis in the 12 months following entry to treatment for first-episode psychosis. Schizophrenia Research. 2004;70(1):61. [: ISI: 000224551100164]

References to studies excluded from this review

    1. Arvanitis L, Bauer D, Rein W. Results of the metatrial project: efficacy and tolerability of four novel compounds in schizophrenia and schizoaffective disorder. International Journal of Neuropsychopharmacology. 2002;5(Suppl 1):S188. [: P.4.E.039]
    2. Meltzer HY, Arvanitis L, Bauer D, Rein W, Meta-Trial Study Group Placebo-controlled evaluation of four novel compounds for the treatment of schizophrenia and schizoaffective disorder. American Journal of Psychiatry. 2004;161(6):975–84. [MEDLINE: 15169685; : EMBASE 2004245661] - PubMed
    3. Rein W, Arvanitis L. Antipsychotic effect of four different compounds - results of the metatrial. Journal of the European College of Neuropsychopharmacology. 2003;13(4):S95. [: S.01.01]

References to studies awaiting assessment

    1. D’Souza DC. Pharmacological studies with delta-9-thc in schizophrenic patients versus controls. International Journal of Neuropsychopharmacology. 2002;5(Suppl 1):S47. [: S.49.3]
    2. D’Souza DC, Abi-Saab W, Madonick S, Wray Y, Forselius K, macDougall L, Brush L, Cassello K, Krystal J. Cannabinoids and psychosis: evidence from studies with IV THC in schizophrenic patients and controls. Schizophrenia Research. 2000;41(1):33. [MEDLINE: 97202599]
    3. D’Souza DC, Abi-Saab WM, Madonick S, Forselius-Bielen K, Doersch A, Braley G, Gueorguieva R, Cooper TB, Krystal JH. Delta-9-tetrahydrocannabinol effects in schizophrenia: implications for cognition, psychosis, and addiction. Biological Psychiatry. 2005;57(6):594–608. [MEDLINE: 15780846; : EMBASE 2005138690] - PubMed
    4. D’Souza DC, Gil R, Zuzarte E, Zimmerman L, Abi-Saab D, Damon D, White J, Sernyak M, Krystal J. Tetrahydrocannabinol effects in schizophrenic subjects & healthy controls. Schizophrenia Research. 1997;24(1,2):213. [MEDLINE: 97202599]
    5. D’Souza DCyril, Abi-Saab Walid, Belger Aysenil, Adams Steve, Madonick Steve, Larvey Kristine, Cassello Karyn, Sernyak Michael, Krystal John. Cannabinoid sensitivity in schizophrenia: evidence from a study with intravenous tetrahydrocannabinol in schizophrenics and controls. 21st Collegium Internationale Neuro-Psychopharmacologicum Congress; Glasgow, UK. 1998 Jul 12-16; 1998. [: APA2006L1.4102]
    6. D’Souza DD, Abi-Saab W, Madonic S, Belger A, Larvey K, Cassello K, Forselius K, Sernyak M, Krystal Cannabinoids and psychosis: evidence from studies with IV THC in schizophrenics and controls. Schizophrenia Research. 1999;1, 2 & 3:104. [MEDLINE: 97202599]
    1. Leweke M, et al. Cannabidiol versus amisulpiride for schizophrenia. Stanley Foundation Research Programs; 2000.
    1. Leweke FM. A 31-day, double-blind, randomized, placebo-controlled cross-over study of cannabidiol as monotherapy in 16 patients with schizophrenia. Stanley Foundation Research Programs; 2004. [: 05T–678]

Additional references

    1. Altman DG, Bland JM. Detecting skewness from summary information. BMJ. 1996;313:1200. - PMC - PubMed
    1. Andreasen NC. Negative symptoms in schizophrenia. Archives of General Psychiatry. 1983;39:784–8. - PubMed
    1. Andreasson S, Allebeck P, Engstrom A, Rydberg U. Cannabis and schizophrenia: a longitudinal study of Swedish conscripts. Lancet. 1987;2:1483–6. - PubMed
    1. Arseneault L, Cannon M, Poulton R, Murray R, Caspi A, Moffit TE. Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study. BMJ. 2002;325:1212–213. - PMC - PubMed
    1. Ashton CH. Pharmacology and effects of cannabis: a brief review. British Journal of Psychiatry. 2001;178:101–6. - PubMed

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