Recherche d’association entre abus de cannabis et bipolarité : étude sur un échantillon de patients hospitalisés pour un trouble bipolaire

Abstract

IntroductionCannabis use is very frequent in bipolar disorder and has been found to increase the duration and frequency of manic symptoms while decreasing those of depression. Bipolar patients who use cannabis were shown to have poorer compliance to treatment, more symptoms that are psychotic and a worse prognosis than patients who do not. In this study, we have evaluated the importance of cannabis use among bipolar patients admitted to the Psychiatric Hospital of the Cross, Lebanon (Hôpital Psychiatrique de la Croix [HPC]) as well as the clinical differences between cannabis users and non-users. MethodsOver a period of 13 months, we recruited the patients admitted to HPC for bipolar disorder according to the MINI DSM-IV criteria. These patients were screened for substance abuse/dependence and were accordingly divided into 2 groups: cannabis users and cannabis non-users. Both groups were interviewed by a medical student and asked to answer the following questionnaires: the MINI DSM-IV, the Young Mania Rating Scale (YMRS) for evaluating manic episodes, the Montgomery and Åsberg Depression Rating Scale (MADRS) for evaluating depressive episodes, the Scale for the Assessment of Positive Symptoms (SAPS) to assess psychotic symptoms associated to the bipolar disorder, and the Cannabis Abuse Screening Test (CAST) for evaluating the importance of cannabis consumption. The study's exclusion criteria were the following: diagnosis of a confusional state, schizophrenia and other psychotic disorders, dementia, age less than 18 years old or superior to 85 years old, and non-cooperation. ResultsAmong the 100 bipolar patients included in the study, 27 (27 %) were cannabis users. Eight of these 27 patients were first admitted to HPC for substance abuse and then included in the study after a bipolar disorder was diagnosed according to the MINI DSM-IV criteria. Cannabis use was found to be more prevalent in young males with a mean age of 20.3 years old at the first contact with the substance. Compared to non-users, cannabis users were found to be younger (33.6 vs. 43.0 years old), more commonly male (77.8 % vs. 49.3 %), and were symptomatic at a younger age (24.6 vs. 30.8 years old). Cannabis users had more hospital admissions in total (6.0 vs. 3.7), and per year (0.73 vs. 0.44) as well as higher socio-economical state. There was a linear relationship between the monthly income per household and cannabis consumption with an OR increasing with the monthly income. Consumers presented more often in a manic state (59.3 %) than in a depressed state (11.1 %). The respective scores of consumers and non-consumers were: YMRS (30.3 vs. 32.1), MADRS (38 vs. 39.5), SAPS (22.7 vs. 23.2). Among cannabis users, 55.6 % and 33.3 % represent the respective percentages of cannabis abuse and dependence. The mean CAST score in these patients was 13.4. DiscussionCompared to the results in the literature, cannabis use in bipolar disorder was found to be lower in our sample. Cannabis use was also associated with an earlier onset of the bipolar disorder as well as a higher number of hospitalizations per year. The age at the diagnosis of the bipolar disorder was 6.2 years lower among cannabis users. Cannabis users had scores of depression, mania and psychotic symptoms statistically similar to those of the non-consumers.