Despite recent advances in the treatment of schizophrenia and schizophreniform disorders, there is still a need to develop efficient and better tolerated psychopharmacological approaches to this group of diseases. The endogenous cannabinoid system provides a promising target in the pharmacotherapy of these disorders. This approach is based upon recent findings indicating that the human endogenous cannabinoid system is significantly involved in the pathogenesis of schizophrenia and that cannabidiol is effective in treating acute psychotic symptoms of schizophrenic patients. We will investigate cannabidiol versus placebo in a randomized, double blind design with extensive safety measures.

The primary hypothesis to be tested is that Cannabidiol is expected to be superior to placebo in the treatment of acute schizophrenic and schizophreniform psychoses with regard to its antipsychotic efficacy.