This study, funded by the Organization of American States (OAS), focuses on the investigation of neuropsychological and neuroanatomic aspects in crack users, from a sample recruited in 3 South American countries, allowing for a broader view of the problem. The Center for Drug and Alcohol Research - CPAD / HCPA / UFRGS is responsible for the coordination in Brazil. This project aims to contribute with a greater knowledge about the mechanisms involved in cognitive and neurobiological dysfunction in crack users, and to evaluate possible levels of severity of the disease over a period of the user's life, which present different clinical conditions and responses to the treatments available today. It is expected in future to ground public policies that guide more directed treatment to these patients, being able to increase the rates of adherence to treatment and to diminish the chance of early relapse.