Model psychosis refers to experimentally induced symptoms resembling schizophrenia, such as withdrawal from reality, perceptual disturbances, thought disorders, delusions, and sometimes hallucinations. These altered states of consciousness help researchers understand aspects of schizophrenia. The endocannabinoid system has become a focus of investigation due to its discovery and epidemiological evidence linking cannabis use to the onset and course of schizophrenia. Most studies examine cannabis and cannabinoid effects not directly related to psychosis. This review summarizes studies relevant to or designed as model psychosis experiments, examining their contribution to understanding endocannabinoid functioning in psychosis and schizophrenia, and outlines future research directions and cross-links to other modeling approaches.
In people with schizophrenia, in the prodromal phase, and in healthy volunteers given synthetic delta-9-tetrahydrocannabinol (THC), performance on a test of visual information processing (the Binocular Depth Inversion Illusion Test) was similarly impaired, and all three groups differed significantly from healthy controls who received no drug. On the Brief Psychiatric Rating Scale, the THC-treated group and the prodromal group did not differ significantly, while both differed from the schizophrenia group and from controls. The findings suggest that THC-induced altered states can model psychotic disorders, especially their prodromal states, and help explain the pro-psychotic effects of high-THC cannabis.