Study of the Impact of Cannabis Use on Perceptual and Memory Processes as Well as On Positive and Negative Symptoms in Patients With Schizophrenia

Abstract

Cannabis, as the most widely used illicit substance in the world, also remains among the most frequently used psychoactive substances by patients with schizophrenia. It is well known that cannabis use in schizophrenia patients favors relapse, resistance to antipsychotic treatments and therefore more frequent hospitalizations. However, many studies report considerable improvement in cognitive performance in substance users, while others show the opposite. Hence, the aim of our study is to examine the relationship between schizophrenia and cannabis use in clinical and socio-de- mographic aspects. This is a cross-sectional study of patients with schizophrenia hospitalized for relapse at the Ar-Razi psychiatric hospital in Salé, Morocco. A questionnaire was established in order to search for socio- demographic data, evolutionary and prognostic criteria of the disease. Cannabis use was assessed using the Cannabis Abuse Screening Test (CAST), for the severity of schizophrenia symptoms we used the Positive And Negative Syndrome Scale (PANSS) and for perceptual and memory abilities we used the numerical version of the Rey's Complex Figure-A (RCF-A). It was found that in a sample of 115 schizophrenic patients, 47.82% (n=55) were cannabis users. The mean PANSS (negative) and (general psychopathology) scores of non-cannabis users were significantly higher than those of cannabis users with P values of (P<0.001) and (P<0.005) respectively. For the numerical assessment scores of the RCF-A, cannabis users had a significantly higher mean score than non-cannabis users (copy phase (P<0.016) and memory (P<0.001) As one of the leading risk factors for the emergence of schizophre- nia, chronic cannabis use also has a negative influence on the prognosis of patients already suffering from schizophrenia. Nevertheless, the results of our study show that cannabis-using schizophrenic patients had fewer negative symptoms according to the PANSS and an improved cognitive performance compared to non- cannabis-using patients.