(Cannabidiol (CBD) and Schizophrenia Treatment) "These studies suggest, therefore, that CBD has an antipsychotic-like profile in healthy volunteers and may possess antipsychotic properties in schizophrenic patients, but not in the resistant ones. Confirming this suggestion, a preliminary report from a 4-week, double-blind controlled clinical trial, using an adequate number of patients and comparing the effects of CBD with amisulpride in acute schizophrenic and schizophreniform psychosis, showed that CBD significantly reduced acute psychotic symptoms after 2 and 4 weeks of treatment when compared to baseline. In this trial CBD did not differ from amisulpride except for a lower incidence of side effects (49).
"In conclusion, results from pre-clinical and clinical studies suggest that CBD is an effective, safe and well-tolerated alternative treatment for schizophrenic patients. Future trials of this cannabinoid in other psychotic conditions such as bipolar disorder (50) and comparative studies of its antipsychotic effects with those produced by clozapine in schizophrenic patients are clearly needed."

Source

"Zuardi, A.W.; Crippa, J.A.S.; Hallak, J.E.C.; Moreira, F.A.; and Guimarães, F.S., "Cannabidiol, a Cannabis sativa constituent, as an antipsychotic drug," Brazilian Journal of Medical and Biological Research (Ribeirão Preto, Brazil: April 2006), Volume 39, Issue 4, p. 427-428.
http://www.scielo.br/pdf/bjmb…