Dual Disorders in Cannabis Misuse

Abstract Cannabis use is associated with a wide range of mental disorders. One possible pathogenic mechanism is through the action of tetrahydrocannabinol in the cannabinoid system. Such system is widely distributed in the brain, and has an important role in emotional regulation, response to stress, cognitive function, and neurodevelopment. The use of cannabinoid agonists, above all at an early age and in large quantities, can alter the proper functioning of this system. Another possible explanation is that cannabis use acts on an already vulnerable cannabinoid system, and that vulnerability may contribute to use and the appearance of mental disorders, so alterations in such systems have been described in several mental disorders. In the Madrid Study on the Prevalence of Dual Pathology in subjects in treatment, we found that three quarters of cannabis addicts had a dual diagnosis, mainly associated with psychosis, bipolar disorder, and agoraphobia, and that the presence of these disorders was related to use beginning at an earlier age.