A longitudinal study of adolescents in Dunedin, New Zealand, found that cannabis use in adolescence is a risk factor for adult psychosis. The study followed 1037 individuals born in 1972-3, with a 96% follow-up rate at age 26. Psychotic symptoms were assessed at age 11, and drug use at ages 15 and 18. Data from 759 participants were analyzed, with three groups based on cannabis use: controls (never or once/twice), cannabis users by age 18, and cannabis users by age 15. Those who used cannabis by age 15 had a fourfold increased risk of schizophrenia diagnosis at age 26, even after controlling for childhood psychotic symptoms. Early cannabis use (by age 15) was associated with greater risk than later use (by age 18). Cannabis use did not predict depressive outcomes. The study suggests that cannabis use in adolescence increases the likelihood of experiencing schizophrenia symptoms in adulthood. The findings align with a Swedish study, adding evidence that cannabis use is not secondary to pre-existing psychosis. The study highlights the need for early intervention for psychologically vulnerable adolescents. The study also notes that cannabis use is specific to schizophrenia risk, not other drugs. The findings require replication in larger studies with detailed measures of cannabis use and schizophrenia. The study also discusses a case of antibody deficiency associated with carbamazepine use, highlighting the need for monitoring in patients with recurrent infections.A longitudinal study of adolescents in Dunedin, New Zealand, found that cannabis use in adolescence is a risk factor for adult psychosis. The study followed 1037 individuals born in 1972-3, with a 96% follow-up rate at age 26. Psychotic symptoms were assessed at age 11, and drug use at ages 15 and 18. Data from 759 participants were analyzed, with three groups based on cannabis use: controls (never or once/twice), cannabis users by age 18, and cannabis users by age 15. Those who used cannabis by age 15 had a fourfold increased risk of schizophrenia diagnosis at age 26, even after controlling for childhood psychotic symptoms. Early cannabis use (by age 15) was associated with greater risk than later use (by age 18). Cannabis use did not predict depressive outcomes. The study suggests that cannabis use in adolescence increases the likelihood of experiencing schizophrenia symptoms in adulthood. The findings align with a Swedish study, adding evidence that cannabis use is not secondary to pre-existing psychosis. The study highlights the need for early intervention for psychologically vulnerable adolescents. The study also notes that cannabis use is specific to schizophrenia risk, not other drugs. The findings require replication in larger studies with detailed measures of cannabis use and schizophrenia. The study also discusses a case of antibody deficiency associated with carbamazepine use, highlighting the need for monitoring in patients with recurrent infections.