Non-replication of interaction between cannabis use and trauma in predicting psychosis

Cannabis use is considered a component cause of psychotic disorder interacting with genetic and environmental risk factors in increasing psychosis risk (Henquet et al., 2008). Recently, two cross-sectional and one prospective study provided evidence that cannabis use interacts additively with trauma to increase psychosis risk (Houston et al., 2008, Harley et al., 2010 and Konings et al., 2011). In an attempt at further replication, we examined prospective data from the German Early Developmental Stages of Psychopathology (EDSP) study (Wittchen et al., 1998b and Lieb et al., 2000)