Kendler KS, et al. - Researchers followed up the individuals with a registration of substance-induced psychotic disorder between 1997 and 2015 in national medical registries (N=7,606) for a mean of 84 months, in order to ascertain the etiology of substance-induced psychotic disorder and its progression to schizophrenia. Observation revealed large elevations in standardized familial risk scores for drug abuse and alcohol use disorder and modest elevations for nonaffective psychosis among individuals with substance-induced psychotic disorder. Substantial drug exposure in individuals at high familial risk for substance abuse and moderately elevated familial risk for psychosis seemed leading to substance-induced psychotic disorder. Progression from substance-induced psychosis to schizophrenia could be predicted by familial risk for psychosis, but not by substance abuse. Schizophrenia following substance-induced psychosis seems to be a drug-precipitated disorder, not a syndrome predominantly caused by drug exposure, in highly vulnerable individuals.