Drug abuse, misuse, and addiction are major issues in society because of their enormous personal, social, and economic costs and their important psychiatric components. Many drug treatment programmes are run by psychiatrists, and the evidence strongly supports the notion that a significant proportion of severe drug abusers are psychiatrically ill. Moreover, drug misuse appears to be becoming more frequent in patients with other psychiatric disorders, where it can lead to problems in treatment and poorer outcomes. It is therefore essential for all psychiatrists and related health professionals to have a good understanding of the basis of drug misuse.
