Substance use disorders (SUDs) have had increased prevalence in many parts of the world in recent years, but especially in the United States, occurring in all racial, ethnic, demographic, and socioeconomic groups. They encompass the use of tobacco and alcohol, misuse of prescription medications, and use of illegal drugs. Together, they contribute substantially to overall morbidity and mortality, including for maternal, fetal, and neonatal populations.

In the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) (DSM-5), substance use disorder terminology replaces substance abuse found in Diagnostic and Statistical Manual of Mental Disorders (4th ed.). This change reflects the movement toward considering addiction to be a brain disease with physical and behavioral findings. The DSM-5 criteria for SUD is listed in Table 19-1.

The diagnosis of addiction follows the criteria for SUD fairly closely and is defined as a primary, chronic disease of brain reward, motivation, memory, and related circuitry as defined by the American Society of Addiction Medicine. Substance dependence is present when withdrawal symptoms are precipitated by abrupt discontinuation of the substance use.

Addiction causes the compulsive use of one or more substances despite significant health and personal sequelae. It disrupts the activity of the brain responsible for reward, motivation, judgment, learning, and memory, and by so doing also disrupts the functioning of families, relationships, and communities. Like diabetes, heart disease, and cancer, addiction is caused by a complex interplay between behavioral, biological, genetic, and environmental factors. An SUD is a chronic, relapsing disease and simultaneous use of multiple substances (or “polysubstance abuse”) is common. Without treatment, it leads to other physical and mental health disorders, and, over time, may become more severe, disabling, and life-threatening. Recovery is the process in which patients abstain from relevant substances and work on improving overall health by leading a self-directed (instead of substance-directed) life.

An SUD is distinct from chronic pain syndromes, although both involve substance tolerance and physical dependence and the two conditions may co-occur.