A new study shows that alcohol cannabis and other illicit drugs can greatly increase the risk of developing schizophrenia in later life. Previous research has analysed potential links between substance abuse and schizophrenia. However due to methodological limitations in the existing literature (including lack of adjustment for co-abuse) uncertainties remain. In this new study the authors analysed nationwide Danish registers to establish a cohort of 3133968 individuals identifying 204505 cases of substance abuse and 21305 diagnosed with schizophrenia. Information on substance abuse was taken from various registers and did not include psychotic symptoms caused by substance abuse in the definition.