Substance use disorder is defined as the use of a substance that results in persistent and sometimes pervasive aversive consequences. Substance use disorders have profound economic and public health impacts in the United States. Researchers have identified important biological, psychological, and social factors that predict the development and resolution of substance use disorders. Biological processes related to substance use include physiological reactivity, changes, and adaptations. Psychological processes associated with substance use include conditioning, observational learning, beliefs about substance use, and emotions that cue substance use. Social relationships and environmental stressors also have been found to influence the course of substance use. Diagnostic criteria have been established to define severity and to specify the course of the disorder. Substance use disorders are thought by some to be chronic and progressive, but research on the natural course of these disorders disputes those beliefs.
Impact of Substance Use Disorder
The total costs of abuse of alcohol and abuse of other drugs including tobacco to the American economy has been estimated by the federal government to be more than $400 billion annually. The two most common substances of abuse are tobacco and alcohol. Conservative estimates indicate that about 20% of the population in the United States abuses tobacco, and between 8% and 13% of the population abuses alcohol. Men are more likely to abuse substances than women. Treatment often results in positive outcomes.
Substance abuse has been associated with the five leading causes of death in the United States in 2004: heart disease, cancers, strokes, chronic lower respiratory illnesses, and unintentional injuries. Some ethnic minority groups may be at high risk for substance use problems. For example, liver diseases often associated with alcohol abuse were the sixth leading cause of death for Hispanics and Native Americans. In contrast, liver diseases are not in the 10 leading causes of death for either Whites or Blacks. However, it is also worth noting that there is often wide variation in substance use within demographic groups. Interestingly, Native Americans also have the highest abstention rate from alcohol when compared with any other ethnic group.
In the United States, the recent trend is greater abuse of prescription medications and methamphetamines. Abuse of substances not traditionally classified as psychoactive, such as steroids and erectile dysfunction medications, has been commonly seen over the recent years. Although these substances often are not listed among traditional drugs of abuse, they can become problematic for users.
Substance abuse is strongly associated with legal consequences. In addition to violation of controlled substance statutes, substance abuse has been associated with domestic violence and other violent crimes such as suicide, property damage, vehicular offenses, and sexual perpetration. In the United States, crime-related costs of substance abuse have been projected to be around $100 billion annually, and conservative estimates have indicated that at least 1 million people have substance abuse problems. Substance abuse is also a major contributing factor to traffic and workplace accidents. Extreme substance-related toxicity can contribute to psychotic symptoms, although sometimes those symptoms preceded the substance use and were masked.
Biopsychosocial Model of Substance Use Disorder
Researchers use a biopsychosocial model to understand addictive processes. Biological processes that have been identified include physiological reactivity to the ingestion of substances, physiological changes due to acute or chronic use of substances, and physiological adaptations to the level of exposure to the substances. Physiological reactivity occurs in response to the substance and results in metabolic changes in the body. Substances activate the pleasure-reward system in the brain, which often results in euphoria. Acute or chronic substance abuse can cause neurotoxicity and damage to vital organs. Commonly experienced cognitive impairments include difficulties with short-term and working memory; problems with executive cognitive functions related to decision making, problem solving, impulse control, and abstraction; and, in some cases, difficulties with balance and motor functions. Existing evidence suggests that some physiological changes are reversible, including cognitive impairment, after a period of abstinence.
Psychological processes include behavioral, cognitive, and emotional responses to substance use. Behavioral processes operate according to learning principles. Classical conditioning in substance abuse occurs when particular stimuli are paired or associated with substance use. In substance abuse research, these stimuli are often referred to as cues or triggers. Substance use may occur at an automatic level when cues trigger sub-stance use so quickly that the individual may be momentarily unaware of actions. Common triggers or cues include places, situations, things, physical senses (sensations, sights, sounds, smells, and tastes), emotions, or events that become paired with substance use and may trigger cravings or desires to use.
Operant conditioning operates when substance use is reinforced or punished. Positive reinforcement is conceptualized as a consequence following a behavior that is rewarding or pleasurable and makes it likely that the behavior will be repeated. Substance use can have rewarding properties that positively reinforce the behaviors related to substance use. In addition, substance use can be negatively reinforced. Negative reinforcement occurs when an aversive consequence is lifted or withdrawn, which in effect reduces an aversive experience. Because the aversive consequence is withdrawn or reduced, it makes it more likely that the behavior will be repeated. An example of this process is when someone uses substances because it has reduced pain or discomfort previously (negatively reinforced) as opposed to using substances because it has caused euphoria in the past (positive reinforcement). An excellent and common example of substance use being negatively reinforced among users is when they described using substances to “self-medicate” symptoms. The behavior described as self-medication alludes to a history where the substance use may have caused aversive symptoms to subside. Research has demonstrated that punishment can effectively stop or reduce substance use over the short term but that for long-term changes to occur punishment must be followed by learning new behavior and having that reinforced.
Substance abuse is difficult to change because it is reinforced on a variable schedule. Since substances are sometimes reinforcing and sometimes not, the user cannot predict when substance use will be reinforcing and continues using substances in the hope that the next event will be reinforcing. Variable reinforcement is one process that contributes to the transition from recreational use to substance abuse.
Observational learning also is a powerful predictor of substance use. Youths and young adults are very much influenced by observing and then modeling the behaviors of significant others in their lives. Before adolescence, youths tend to model the substance use behavior of their parents. Researchers have noted that substance abuse tends to be intergenerational in family systems. The assumption for many years was that this intergeneration “transmission” of substance abuse must be genetic. However, recent research has identified that at least part of the intergenerational phenomenon in family systems appears to be learned behavior, principally from observing and modeling parents who misuse substances. As youths move into the teen years and early adulthood, peer groups tend to influence substance use more than parents. In addition, researchers have found that adolescents and young adults tend to overestimate the substance use of peers and at the same time underestimate their own substance use.
Cognitive factors related to addictive processes include expectancies about substance use, motivation to change, and self-efficacy. Expectancies are beliefs about the expected effects of substance use. Expectancies can develop through personal experience or observational learning. As an example of the latter, to sell their products advertisers of alcohol beverages often advertise that alcohol makes people sexy or socially attractive, beliefs that are assumed by youths who observe the advertisements. Positive expectancies refer to beliefs that substance use will provide a desirable outcome, whereas negative expectancies refer to beliefs that substance use will lead to an undesirable outcome. Positive expectancies have been found to predict continued and sometimes increased substance use, whereas negative expectancies have been linked to reductions.
Motivation to change determines whether a user will consider and ultimately change substance use. Decisions to change often follow a process known as the decisional balance, where a user considers the pros and cons for change. Ambivalence is quite normal for someone contemplating change. If a user decides that the pros for change outweigh the cons, then she or he likely will be more committed to changing behavior and seeking help. Self-efficacy also has been found to predict substance abuse. Self-efficacy is a term from social learning theory that describes, in the case of substance abuse, whether a person has competence and confidence to negotiate a specific situation without use of substances. Lower self-efficacy in a situation predicts poorer substance use outcomes in that situation.
Cognitive impairment is of concern when a user has engaged in extreme or chronic substance abuse. Perceptual problems result from acute intoxication. One phenomenon, substance use myopia, refers to how cognitive processes become impaired as intoxication increases, literally narrowing a person’s ability to see or accurately perceive events occurring around him or her. During substance use myopia, clients are vulnerable to impulsive, disinhibited, and risky behavior because perception of risk is impaired. As an example, substance-induced myopia leads to poor judgment, such as believing that it is safe to drive under the influence of substances.
Emotions and moods also have been associated with substance abuse. Many users report links between emotional events and substance use behavior, and relapses have been linked to extreme emotions (positive or negative). Users often use substances to manage emotions and moods but also report that substance use contributes to loss of emotional control. Research has established that chronic substance use may disrupt emotional expression and contribute to substance induced dysphoria.
Social and environmental factors linked to addictive processes may include relationship stressors and environmental stressors such as unemployment and poverty. Some researchers believe that a major function of substance misuse is in tension reduction. Changes in relationship interactions and environmental conditions have been linked to changes in substance use. Youths are especially vulnerable to changes in the environment and substance abuse in that age group can be influenced heavily (both positively and negatively) by such changes.
Diagnosis of Substance Use Disorder
Misuse of substances can be diagnosed by means of structured clinical interviews that assess for criteria specified by the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV). The most com-monly used interviews are the Structured Clinical Interview for DSM-IV (SCID) and the Diagnostic Interview Schedule (DIS). Substance misuse is classified as either substance abuse or dependence for a single substance or for multiple substances. DSM-IV diagnostic categories also include “specifiers” that denote abuse with or without physiological dependence and “course specifiers” that define the course of the disorder, including early full remission, early partial remission, sustained full remission, sustained partial remission, on agonist therapy (such as methadone), or in a controlled environment (where access is restricted).
DSM-IV diagnoses conceptualize substance abuse as a chronic condition subject to periods of remission. However, researchers have found evidence that a subgroup of people diagnosed with alcohol dependence, for example, show evidence of controlled moderate drinking without problems later in life. In addition, other research shows that the course of substance abuse does not necessarily worsen with time nor do users need to hit the bottom to want help. Substance use diagnoses for adolescents have been found to be very unstable. Many adolescents meeting DSM-IV criteria for substance abuse or dependence experience a “maturing out” process as they age and go on to adult lives free of substance-related problems. Therefore, substance use diagnoses for adolescents should be interpreted with caution.
- DiClemente, C. C. (2003). Addiction and change: How addictions develop and addicted people recover. New York: Guilford Press.
- Donovan, D. M., & Alan Marlatt, G. (Eds.). (2005). Assessment of addictive behaviors (2nd ed.). New York: Guilford Press.
- McCrady, B. S., & Epstein, E. E. (Eds.). (1999). Addictions: A comprehensive guidebook. New York: Oxford University Press.
- Miller, R., & Carroll, K. M. (2006). Rethinking substance abuse: What the science shows, and what we should do about it. New York: Guilford Press.