Addressing the context and consequences of substance use, misuse, and dependence: A global imperative

Substance use, misuse, and dependence contribute immensely to the global burden of disease [1].Their harms extend far beyond their corrosive effects on health, safety, and wellbeing and additionally include those associated with healthcare expenditures, productivity losses, criminal justice involvement, and other negative effects on social welfare [2].The incidence and harms of substance use, misuse, and dependence involve multilevel explanatory factors [3,4].Interventions to reduce their individual-and population-level harms can often be hampered by biological, psychological, and social complexity, especially because substance use is often syndemic with other health and social problems such as HIV infection, hepatitis B and C, mental health disorders, and violence [5,6].It is in this context that PLOS Medicine devotes its November 2019 Special Issue to research on substance use, misuse, and dependence.The contributions to the issue cover a wide range of topics, including social determinants of substance use, health harms resulting from substance use, and interventions to prevent or reduce the harms associated with substance use.There are also a number of gaps in terms of the topics covered, the robustness of the evidence, and its global scope.