Cannabis and schizophrenia: characterisation of a risk factor in a sample of Moroccan patients hospitalised for psychosis

Abstract

Background: In addition to the biological plausibility widely described through a very large number of studies, the causal link between cannabis uses and schizophrenia disorders has become illicit internationally and given the scarcity of similar studies in Morocco. Our study consists of a prospective descriptive study in the psychiatric department of the Moulay ben Abdallah Hospital in Essaouira. The sample consisted of 95 patients diagnosed with schizophrenia according to the DSM5 criteria. The diagnostic assessment included the Positive and Negative Syndrome Scale to assess the severity of positive and negative symptoms of schizophrenia as well as the patient’s general psychopathology, the Clinician-Rated Dimensions of Psychosis Symptom Severity to assess the symptom severity of the psychotic dimensions according, and the Cannabis Abuse Screening Test to assess the extent of cannabis use. Results: The mean age of the patients recruited in the study was 33.7 ± 9.37 years with a clear male predominance (p < 0.0001). Cannabis users compared to non-users were younger and comprised only men. Cannabis users also have a lower educational and economic level than non-users. Furthermore, a clear dose effect of cannabis uses on the onset of positive and negative symptoms of schizophrenia. The temporality criterion is clear in our study, since the predictivity of the parameter: “age of onset of cannabis use” is highly significant (p = 0.000). These results suggest that cannabis use can be considered as the most illicit risk factor for the development and/or onset of schizophrenia. Conclusions: These results suggest that there is a causal relationship between cannabis use and/or dependence (problematic use) and the onset and/or worsening of schizophrenic disorder. This means that problematic cannabis use can be considered as a real risk factor for the emergence and development of schizophrenic disorder.