The first human study of cannabidiol CBD and its possible antipsychotic effects was in a schizophrenic patient who was hormonally disturbed by classical antipsychotics (Zuardi et al. 1995).
The patient was a 19-year-old girl treated at the Ribeirao Preto clinic. She suffered from increased aggressiveness, auto-aggression, incoherent thinking and auditory hallucinations. Since starting CBD, she has steadily increased the dose to 1500mg twice daily for 4 weeks. After that, the doses of CBD were replaced with placebo for 4 days. Then she was given regular Haloperidol at a dosage appropriate to her condition. In cases of deterioration, the patient was given Diazepam. The average daily dosage of Diazepam decreased with CBD from 16.3 mg to 5.7 mg.
The patient was under constant observation by 2 psychiatrists and 2 nurses, and her sound recording was constantly made. After the end of the experiment, the sound recordings were randomly analyzed by an independent psychiatrist, who made the following conclusion: The symptoms of schizophrenia decreased with the intake of CBD and, conversely, the symptoms increased after the end of the CBD intake. The positive effect of CBD was not fixed by the subsequent intake of Haloperidol. Improvement in the patient’s condition was observed in all areas studied, including psychotic symptoms.
Effects of CBD on psychosis in Parkinson’s disease
Another open pilot study was conducted at the University of São Paulo, which showed the effectiveness of the treatment of psychotic symptoms with CBD in patients with Parkinson’s disease (Zuardi et al. 2008).
Six patients (4 males and 2 females) diagnosed with Parkinson’s disease and psychoses for 3 months participated in this study. All patients received oral CBD at a dosage of 150 mg daily for 4 weeks as an adjunct to their standard treatment. During this treatment with CBD, there was a significant reduction in psychotic symptoms in all patients. Also, CBD did not impair motor function and did not have other negative effects.
The authors of the study concluded that the use of CBD may be an effective, well-tolerated and safe way to treat psychosis in Parkinson’s disease.
CBD and schizophrenia – a clinical study on 42 patients
The first large clinical studies of the therapeutic potential of CBD in the treatment of acute symptoms of schizophrenia were carried out at the Czech University of Kolin (Kolín) on 42 patients. Studies have shown that taking CBD significantly reduces psychopathic symptoms compared to baseline (Leweke et al. 2012). Half of the patients received 800mg of CBD daily for 4 weeks, while the other half received the conventional antipsychotic Amisulpride.
Both treatments resulted in a significant improvement in the clinical signs of the disease, however CBD with significantly fewer adverse side effects. Also, in patients of the first group, there was an increase in the concentration of anandamide (an endogenous cannabinoid that binds in the brain to the same receptors that interact with psychoactive trans-tetrahydrocannabinol, which is a neurotransmitter and neuroregulator. This newly discovered molecule plays a role in the mechanisms of origin of pain, depression, appetite , memory and reproductive function) in the patient’s blood.
The authors of the study found that “prevention (inhibition) of the deactivation of anandamide contributes to the manifestation of the antipsychotic effects of CBD, which leads to significant changes in the treatment of schizophrenia.”
