Hjorthøj C, et al. - Researchers sought to determine if infections elevate the risk of substance-induced psychosis. Further, they assessed whether infections enhance the risk of converting from substance-induced psychosis to schizophrenia. The combined nationwide Danish registers was assessed for data of individuals born in Denmark since 1981. Assessment of 2,256,779 individuals was done; among these, 3,618 cases of incident substance-induced psychosis were recorded. The analysis suggests that the risk of substance-induced psychosis increases with all infections. The risk was doubled for the first 2 years. They identified the most strong association of hepatitis with substance-induced psychosis. Link of different types of infections with different types of substance-induced psychosis was observed. Conversion to schizophrenia after substance-induced psychosis was observed in correlation with hepatitis only. Results here support the hypothesis of an immunological component to psychosis.