Evaluation of the Antipsychotic Efficacy of Cannabidiol in Acute Schizophrenic Psychosis
Status:
Completed
Trial end date:
2008-03-01
Target enrollment:
Participant gender:
Summary
A controlled, randomized study on the treatment of schizophrenic psychosis with cannabidiol,
a phytocannabinoid is performed. This approach is based upon recent findings indicating that
the human endogenous cannabinoid system is significantly involved in the pathogenesis of
schizophrenia. Our group has shown, for example, that Δ9-tetrahydrocannabinol (Δ9-THC) is
able to provoke schizophrenia-like psychotic symptoms in healthy volunteers. This, as well as
the capability of Δ9-THC to exacerbate productive psychotic symptoms in schizophrenic
patients, has recently been confirmed by others. Furthermore, we found that the en-dogenous
brain constituent anandamide, an endogenous Δ9-THC agonist, is significantly elevated in the
CSF of schizophrenic patients. Cannabinergic substances such as anandamide may enhance
dopaminergic neurotrans-mission by increasing dopamine turnover. They may also influence the
onset or course of schizophrenia by as yet unidentified mechanisms We seek to investigate the
efficacy of cannabidiol in the treatment of schizophrenic and schizophreniform psy-choses,
because there is evidence that CB1 antagonists such as SR141716 and cannabidiol have
antipsychotic effects comparable to those of classic neuroleptic drugs. Furthermore,
cannabidiol is well tolerated showing few side effects in humans. Cannabidiol may serve as an
antipsychotic medication that is not primarily based upon an antidopaminergic but upon
different mechanisms, especially anticannabinergic ones. It may therefore be an effec-tive
medication in at least a subgroup of schizophrenic and schizophreniform patients and may be
expected to show additional anxiolytic effects and only minor side effects.
The control condition in this parallel design will be an established neuroleptic treatment
with amisulpride that is primarely an antidopaminergic drug. Thus, we will study not only the
antipsychotic efficacy of cannabidiol, but we will also compare the effects of both treatment
strategies on side effects and neuropsychological functioning.