Substance Use Disorders: Addiction

The essential feature of a substance use disorder is a cluster of cognitive, behavioral, and
physiological symptoms indicating that the individual continues using the substance despite
significant substance-related problems. As seen in Table 1, the diagnosis of a substance
use disorder can be applied to all 10 classes included in this chapter except caffeine.
For certain classes some symptoms are less salient, and in a few instances not all symptoms
apply (e.g., withdrawal symptoms are not specified for phencyclidine use disorder, other
hallucinogen use disorder, or inhalant use disorder).
An important characteristic of substance use disorders is an underlying change in brain circuits
that may persist beyond detoxification, particularly in individuals with severe disorders.
The behavioral effects of these brain changes may be exhibited in the repeated relapses and intense
drug craving when the individuals are exposed to drug-related stimuli. These persistent
drug effects may benefit from long-term approaches to treatment.
Overall, the diagnosis of a substance use disorder is based on a pathological pattern of
behaviors related to use of the substance. To assist with organization, Criterion A criteria can
be considered to fit within overall groupings of impaired control, social impairment, risky use,
and pharmacological criteria. Impaired control over substance use is the first criteria grouping
(Criteria 1–4). The individual may take the substance in larger amounts or over a longer period
than was originally intended (Criterion 1). The individual may express a persistent desire
to cut down or regulate substance use and may report multiple unsuccessful efforts to
decrease or discontinue use (Criterion 2). The individual may spend a great deal of time obtaining
the substance, using the substance, or recovering from its effects (Criterion 3). In
some instances of more severe substance use disorders, virtually all of the individual’s daily
activities revolve around the substance. Craving (Criterion 4) is manifested by an intense desire
or urge for the drug that may occur at any time but is more likely when in an environment
where the drug previously was obtained or used. Craving has also been shown to
involve classical conditioning and is associated with activation of specific reward structures
in the brain. Craving is queried by asking if there has ever been a time when they had such
strong urges to take the drug that they could not think of anything else. Current craving is often
used as a treatment outcome measure because it may be a signal of impending relapse.
Social impairment is the second grouping of criteria (Criteria 5–7). Recurrent substance
use may result in a failure to fulfill major role obligations at work, school, or home (Criterion
5). The individual may continue substance use despite having persistent or recurrent
social or interpersonal problems caused or exacerbated by the effects of the substance (Criterion
6). Important social, occupational, or recreational activities may be given up or reduced
because of substance use (Criterion 7). The individual may withdraw from family
activities and hobbies in order to use the substance.
Risky use of the substance is the third grouping of criteria (Criteria 8–9). This may take
the form of recurrent substance use in situations in which it is physically hazardous (Criterion
8). The individual may continue substance use despite knowledge of having a persistent
or recurrent physical or psychological problem that is likely to have been caused or
exacerbated by the substance (Criterion 9). The key issue in evaluating this criterion is not
the existence of the problem, but rather the individual’s failure to abstain from using the
substance despite the difficulty it is causing.

Pharmacological criteria are the final grouping (Criteria 10 and 11). Tolerance (Criterion
10) is signaled by requiring a markedly increased dose of the substance to achieve the
desired effect or a markedly reduced effect when the usual dose is consumed. The degree
to which tolerance develops varies greatly across different individuals as well as across
substances and may involve a variety of central nervous system effects. For example, tolerance
to respiratory depression and tolerance to sedating and motor coordination may
develop at different rates, depending on the substance. Tolerance may be difficult to determine
by history alone, and laboratory tests may be helpful (e.g., high blood levels of the
substance coupled with little evidence of intoxication suggest that tolerance is likely). Tolerance
must also be distinguished from individual variability in the initial sensitivity to
the effects of particular substances. For example, some first-time alcohol drinkers show
very little evidence of intoxication with three or four drinks, whereas others of similar
weight and drinking histories have slurred speech and incoordination.
Withdrawal (Criterion 11) is a syndrome that occurs when blood or tissue concentrations
of a substance decline in an individual who had maintained prolonged heavy use of
the substance. After developing withdrawal symptoms, the individual is likely to consume
the substance to relieve the symptoms. Withdrawal symptoms vary greatly across
the classes of substances, and separate criteria sets for withdrawal are provided for the
drug classes. Marked and generally easily measured physiological signs of withdrawal are
common with alcohol, opioids, and sedatives, hypnotics, and anxiolytics. Withdrawal
signs and symptoms with stimulants (amphetamines and cocaine), as well as tobacco and
cannabis, are often present but may be less apparent. Significant withdrawal has not been
documented in humans after repeated use of phencyclidine, other hallucinogens, and inhalants;
therefore, this criterion is not included for these substances. Neither tolerance nor
withdrawal is necessary for a diagnosis of a substance use disorder. However, for most
classes of substances, a past history of withdrawal is associated with a more severe clinical
course (i.e., an earlier onset of a substance use disorder, higher levels of substance intake,
and a greater number of substance-related problems).
Symptoms of tolerance and withdrawal occurring during appropriate medical treatment
with prescribed medications (e.g., opioid analgesics, sedatives, stimulants) are specifically
not counted when diagnosing a substance use disorder. The appearance of normal,
expected pharmacological tolerance and withdrawal during the course of medical treatment
has been known to lead to an erroneous diagnosis of “addiction” even when these
were the only symptoms present. Individuals whose only symptoms are those that occur
as a result of medical treatment (i.e., tolerance and withdrawal as part of medical care
when the medications are taken as prescribed) should not receive a diagnosis solely on the
basis of these symptoms. However, prescription medications can be used inappropriately,
and a substance use disorder can be correctly diagnosed when there are other symptoms
of compulsive, drug-seeking behavior.