[Consumption of cannabis in adolescents]

Over the past 10 years, the consumption of cannabis among adolescents has dramatically increased. Today, adolescent cannabis use is a major public health problem. Two forms of cannabis are commonly smoked: herb (marijuana) and resin. These forms have a high concentration of tetrahydrocannabinol, the active molecule of cannabis. Recent research has helped understand how the cannabinoid system works. This system combines specific receptors and specific molecules: the endocannabinoids. The effects of cannabis use are now well documented. Some adolescents report subjective positive effects. They use it not only on a recreational basis, but also to deal with their emotions. Over the long term, cannabis increases the risk of depression and schizophrenia for those adolescents who are at risk. Use, misuse, and dependence are frequently associated with heavy psychopathologic problems such as vulnerability and depression. Many cannabis dependence psychotherapies have shown their efficacy and efficiency. Motivational interviews, cognitive behavioral therapy, multidimensional family therapy (MDFT), and residential treatment have proved highly effective. MDFT seems very effective, especially in cases of heavy use.