How effective and safe is medical cannabis as a treatment of mental disorders? A systematic review
We conducted a review of systematic reviews (SRs) and randomized-controlled trials (RCTs) to analyze efficacy and safety of cannabis-based medication in patients with mental disorders. Five data bases were systematically searched (2006—August 2018); 4 SRs (of 11 RCTs) and 14 RCTs (1629 participants) were included. Diagnoses were: dementia, cannabis and opioid dependence, psychoses/schizophrenia, general social anxiety, posttraumatic stress disorder, anorexia nervosa, attention-deficit hyperactivity disorder, and Tourette`s disorder. Outcome variables were too heterogeneous to conduct a meta-analysis. A narrative synthesis method was applied. The study quality was assessed using the risk-of-bias tool and SIGN-checklists. THC- and CBD-based medicines, given as adjunct to pharmaco- and psychotherapy, were associated with improvements of several symptoms of mental disorders, but not with remission. Side effects occurred, but severe adverse effects were mentioned in single cases only. In order to provide reliable treatment recommendations, more and larger RCTs with follow-up assessments, consistent outcome measures and active comparisons are needed.
KeywordsMental disorders Cannabis Cannabinoids THC CBD Medical cannabis Treatment
We acknowledge the contribution of Johannes Kabisch, Kathrin Schacherbauer, Sophia Schmieder, Luise Jacob, Christina Adorjan, Udo Bonnet, Jan Copeland, Peter Falkai, Marica Ferri, Christopher Fowler, Winfried Häuser, Derik Hermann, Burkhard Hinz, Michael Höfler, Joseph Kambeitz, Dagmar Koethe, Ludwig Kraus, Markus Leweke, Beat Lutz, Liane Paul, Nina Sarubin, Frank Petzke, Tim Pfeiffer-Gerschel, Lukas Radbruch, Roland Simon, Michael Schäfer and Martin Storr.
This work was prepared in the context of the study “Cannabis: Potential and risks. A scientific analysis (CaPRis)” (PI: 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.
Compliance with ethical standards
Conflict of interest
The authors have no conflict of interest.
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