++
Substance abuse tends to be a chronic, progressive disease. Initiation of substance use is becoming such a common feature of an American adult that many authorities call it normative behavior. At this stage, substance use is typically limited to experimentation with tobacco or alcohol (so-called gateway substances). During adolescence, young people are expected to establish an independent, autonomous identity. They try out a variety of behaviors within the safety of families and peer groups. This process often involves experimentation with psychoactive substances, usually in culturally acceptable settings. Continuation of substance abuse, however, is a nonnormative risk behavior with the potential to compromise adolescent development.
++
The American Psychiatric Association has outlined criteria to judge the severity of substance use disorders (SUD). The most recent version, DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition), has moved from the previous terms “substance abuse” and “substance dependency” to mild, moderate, and severe SUD. There are 11 features described in DSM-5. Patients with mild SUD have two or three features, whereas those with moderate have four or five features without loss of control or compulsive features. Patients with severe SUD have more than six features, including loss of control or compulsive features.
++
Common physiologic effects and symptoms of intoxication (which can occur at any stage of substance use) and withdrawal (a symptom of dependency) for the major classes of substances are shown in Tables 5–1 and 5–2.
++