Cannabis Use and Dependence among French Schizophrenic Inpatients

To assess the prevalence of cannabis use and dependence in a population of schizophrenic inpatients and to compare schizophrenics with and without cannabis consumption.

One hundred one schizophrenic patients were examined during their first week of hospitalization. They answered the PANNS scale of schizophrenia, the CAGE and the Fagerström questionnaire, and the DSM-IV-TR criteria for cannabis, alcohol, opiates, and nicotine use dependence were checked. We also assessed socio-demographic characteristics, the motive of cannabis consumption, and the number of cannabis joints and alcoholic drinks taken.

The prevalence of cannabis consumption was 33.6% among schizophrenic inpatients. Schizophrenics consuming cannabis were younger than non-schizophrenics (33.3 vs. 44.7 years p < 0.0001), more often male (77 vs. 54%, p = 0.02) and had been hospitalized for the first time in psychiatry earlier (24.3 vs. 31.3 p = 0.003). Eighty-eight percent of cannabis consumers were dependent on cannabis. They were more often dependent on opiates (17 vs. 0%) and alcohol (32 vs. 7.4%, p = 0.001) and presented compulsive buying more often (48 vs. 27%, p = 0.04). Logistic regression revealed that factors associated to cannabis consumption among schizophrenics were cannabis dependence, male gender, pathological gambling, opiate dependence, number of joints smoked each day, and compulsive buying.

33.6% of the schizophrenic patients hospitalized in psychiatry consume cannabis and most of them are dependent on cannabis and alcohol. Hospitalization in psychiatry may provide an opportunity to systematically identify a dependence disorder and to offer appropriate information and treatment.