Cannabis et trouble bipolaire : recherche d’une association à partir d’une revue de la littérature

Abstract

Introduction It has been established that cannabis use is involved in the emergence and evolution of psychotic disorders. Although cannabis use is very frequent in mood disorders, there has been a considerable debate about the association observed between these two disorders. This review aims to clarify the relation between cannabis use and bipolar disorder, in order to unveil a possible causality and find the effect of cannabis on the prognosis and expression of bipolarity. Methods The review used MedLine database using the keywords “cannabis” or “marijuana” and “bipolar” or “mania” or “depression”. This search found 36 articles who were clinically relevant to the subject and were included and discussed in this review. Results The first studies discussing the link between cannabis use and psychotic disorders reveal manic features in the substance abuse group, hence suggesting a possible association between cannabis use and bipolar disorder, in favor of triggering a manic episode. According to the studies, between 25 and 64% of bipolar patients are cannabis users, and the prevalence is higher in younger and male patients. The risk of developing a mood disorder is higher among cannabis users compared to the general population. This substance abuse in bipolar disorders would increase the frequency and duration of manic episodes without changing the total duration of mood episodes. In a first episode of bipolar disorder, the use of cannabis would increase the rate of relapses of manic episodes and worsen the prognosis of the disorder. Discussion The frequency of substance abuse in bipolar disorders is higher than the prevalence in the general population, and cannabis is one of the most used illegal substances in the worldwide. Hence, the association between cannabis use and bipolar disorders is frequent. Cannabis users may experience euphoria, relaxation and subjective feelings of well-being; this substance may also have antiepileptic effect, which may explain some of the effects of cannabis on bipolar disorders. In fact, the use of cannabis would increase the frequency and duration of manic episodes in bipolar patients without increasing the total duration of mood episodes, suggesting a possible antidepressing and mood stabilizing effects. This impact of cannabis on mood disorders and its possible pharmacological effect is still controversial and needs further experiencing to be proved.