OPN1MW and schizophrenia: Finally, a randomized clinical trial comparing CBD (200–800 mg/day) for 4 weeks with amisulpride (an atypical antipsychotic dopamine receptor antagonist) in acute schizophrenia patients showed that both treatments were safe and effective; however, CBD patients displayed fewer side effects (no extrapyramidal symptoms, lower prolactin levels, and less weight gain) [188].