Substance use and misuse
Around the world, substance use disorder is best understood along a spectrum that ranges from no use or use that causes no problems (i.e. the majority of people) through occasional use that brings occasional problems of moderate severity (i.e. some people) to frequent use that with severe problems (i.e. a minority of people). Across cultures, few people use substances (<10%) at levels that present severe problems. This chapter provides an overview of global trends of substance use and substance use disorder, offers criteria that define substance use disorder, and presents epidemiology on cannabis, opioids, amphetamine-type stimulants, and cocaine/crack. Relevant findings on public health consequences and intersections between substance use, infectious diseases, and other health threats are presented. A methodological toolbox containing best methods for studying substance use is provided. The chapter closes with a discussion of approaches to treatment and prevention of substance misuse, emphasizing integration of services (e.g. a one-stop shop).