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CLASSIFICATION OF SUBSTANCE-RELATED AND ADDICTIVE DISORDERS
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The substance-related disorders are classified into two categories: (1) substance-use disorders and (2) substance-induced disorders*. The substance-use disorders are characterized according to severity based on the number of relevant symptoms that the patient exhibits. The Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) specifies substance-use disorders that result from the self-administration of several different drugs of abuse.
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The specific criteria for diagnosis of substance-use disorders draw heavily on the concept of the dependence syndrome. This important advance in our thinking about these disorders frames the interactions among the pharmacologic actions of the drug, individual psychopathology, and the effects of the environment in a clinically meaningful construct that is generalizable to all drugs of abuse. This concept is derived from the clinical observation that patients may have maladaptive behavior as a result of drug use without the presence of overt neurophysiologic adaptive changes such as tolerance or withdrawal (also referred to as neuroadaptation). Neuroadaptation is not necessarily dysfunctional if there is no concomitant inappropriate desire (craving) to continue the use of the drug (drug seeking). For example, driving while drunk may have devastating consequences, particularly in the sporadically drinking young driver who has not acquired tolerance to ethanol. In another example, the postsurgical patient who has been receiving morphine for pain relief clearly exhibits neuroadaptation but is not likely to develop the dependence syndrome.
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Fundamental to the concept of the dependence syndrome is the priority of drug seeking over other behaviors in the maintenance of dysfunctional drug use. Lesser weight is attributed to the presence of tolerance or withdrawal. In general, two (or more) individual criteria from among the 11 criteria enumerated in DSM-5, which easily fall into the following three symptom clusters, need to be part of the clinical presentation to support the diagnosis of substance-use disorder: (1) loss of control (i.e., the substance is taken in larger amounts or over a longer period than intended, or there are unsuccessful efforts to reduce use); (2) salience to the behavioral repertoire (i.e., a great deal of time is spent in substance-related activities at the expense of important social, occupational, or recreational activities that are reduced or given up, or there is continued substance use despite knowledge of having a persistent or recurrent physical or psychological problem likely to have been caused or exacerbated by the substance); and (3) neuroadaptation (i.e., the presence of tolerance or withdrawal or craving manifested by a strong desire or urge to use a specific substance).
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Diagnosis of a substance-use disorder by the presence of a given number of symptoms provides at best an incomplete picture of various clinically important features of the illness, such as severity, course, and prognosis, as well as indicated treatment for this heterogeneous patient population. The issue of illness severity is addressed in DSM-5 by severity specifiers, i.e., ...