Heroin and speed users regularly swap between the two drugs and suffer similar physical and psychiatric health problems, new research has shown. The findings of the study, conducted by the National Drug and Alcohol Research Centre, challenge education and safety campaigns that aim at distinct drug-user groups without realising the extent of the crossover between the two. "I don't think we can talk about a heroin user or a speed user any more; the patterns just aren't distinct. They look too similar,'' said Dr Shane Darke, a senior lecturer at the University of New South Wales.