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Drug Use Disorders
Definition
The term substance use disorder has replaced substance abuse and dependence in the diagnostic lexicon. As defined by the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders , “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.” No single pathognomonic symptom is diagnostic of a substance use disorder. Rather, the syndrome is a series of 11 symptoms, of which the individual must meet two or more in the same 12-month period to warrant a diagnosis of a substance use disorder ( Table 365-1 ). These 11 symptoms can be grouped into four general categories:
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Impaired control: taking a substance in larger amounts or for a longer time than intended; persistent desire or unsuccessful attempts to stop or to reduce use; a great deal of time spent using a substance or recovering from the effects of its use; craving
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Social impairment: failure to fulfill role obligations at home, work, or school as a result of repeated substance use; continued substance use despite experiencing interpersonal problems; or reducing or giving up important social, recreational, or occupational activities
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Risky use: recurrent use in hazardous situations (e.g., driving) or despite knowledge that substance use is causing or exacerbating a physical or psychological problem
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Pharmacologic criteria: tolerance and physical dependence, when relevant; not all drugs cause these symptoms
TABLE 365-1
DSM-5 CRITERIA FOR SUBSTANCE USE DISORDERS
Data from Hasin DS, O’Brien CP, Auriacombe M, et al. DSM-5 criteria for substance use disorders: recommendations and rationale. Am J Psychiatry . 2013;170:834-851.
| IMPAIRED CONTROL |
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| SOCIAL IMPAIRMENT |
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| RISKY USE |
|
| PHARMACOLOGIC CRITERIA |
Substance use disorder is diagnosed if 2 or more of these 11 criteria are met within a 12-month period. A substance use disorder is classified as “mild if someone meets 2 or 3 criteria, “moderate” if meeting 4 or 5 criteria, and “severe” if a person meets 6 or more criteria.
∗ ”When relevant” indicates that these criteria are not counted, even if the symptoms are present, when an individual is using legitimately prescribed medications as intended and those medications are helping the person to function better.
For patients who are prescribed medications that can cause tolerance and physical dependence, the diagnostic term substance use disorder should be used only when medication use is problematic; tolerance and physical dependence are not considered criteria for a diagnosis of a substance use disorder in patients who are taking medications such as opioids or sedative-hypnotics exclusively as part of appropriate medical care. If a patient is using legitimately prescribed medications as intended (e.g., opioids for chronic pain or benzodiazepines for panic disorder) and those medications are helping the patient to function better, that patient will not meet criteria for a substance use disorder, even if tolerant to the medication and/or physically dependent upon it.
Epidemiology
Use of illicit drugs and nonmedical use of prescribed drugs are common. Approximately 36 million Americans, representing approximately 13% of the population, report using an illicit drug in the previous month. When asked about their substance use in the past month, about 32 million Americans reported using marijuana (which is now legal for medical and/or recreational purposes in many states), 6.4 million reported using potentially psychoactive prescription drugs nonmedically (2.8 million of whom used prescription pain relievers nonmedically), 2.0 million people used cocaine, and 1.9 million people used hallucinogens. Among youths aged 12 to 17 years, about 9% reported using an illicit drug in the past month. The overall estimated prevalence of illicit intravenous drug use in the United States has increased from between 0.24% and 0.39% a decade or so ago to about 1.5% of adults more recently. , Overdose deaths from opioids, cocaine, and psychostimulants continue to rise in the United States, now exceeding 100,000 per year.
Pathobiology
Drug use disorders involve complex interactions between the pharmacology of a specific drug ( Chapter 27 ), an individual’s genetic makeup, psychological strengths and weaknesses, environmental circumstances, and societal influences (such as physical and perceived drug availability, legal status and cost of the drug, religious and cultural mores, and presence of alternative rewarding activities). Thus, the etiology of drug use disorders can be conceptualized by employing the public health model frequently cited in the study of infectious disease (i.e., as an interaction among the host [which in this case is the potential drug user], the agent [a specific drug], and the environment [the person’s family life and peer group, as well as the social, cultural, and religious attitudes toward use of that substance]).
The Host
A positive family history of a substance use disorder increases the likelihood of both alcohol ( Chapter 364 ) and drug use disorders. Twin studies and adoption studies show that both genetic and environmental factors contribute to this vulnerability, although the precise nature is still unknown.
Psychiatric illness ( Chapter 362 ) influences the likelihood of developing drug use problems. For example, conduct disorder in childhood and adolescence as well as antisocial personality disorder in adulthood predispose to subsequent drug use problems. Psychiatric disorders such as mood disorders are frequently noted in people with drug use disorders. However, the presence of these two disorders in the same person does not necessarily imply causation, even if one of the disorders is manifested first.
Conversely, individual protective factors may reduce the likelihood of a substance use disorder. Individuals who have positive familial relationships, academic success, and meaningful religious affiliations have a lower likelihood for development of drug problems. The fact that many people have a mixture of risk and protective factors speaks to the complex etiologic nature of drug use disorders.
The Agent
Most drugs of misuse are inherently reinforcing; animals typically will self-administer most of the commonly misused drugs. Not all drugs are equally reinforcing, however. Some individuals like the stimulating effects of drugs such as cocaine and amphetamine, whereas others experience that level of stimulation as uncomfortable. Some individuals like the relaxation induced by drugs such as marijuana and sedative-hypnotics, whereas others feel overly slowed down by these drugs. Although some individuals gravitate toward particular drugs because of their specific pharmacologic properties, others use a variety of drugs indiscriminately, based on level of availability; some of these individuals are primarily seeking to alter their current emotional state, regardless of the direction in which it is changed. The reinforcing properties of many drugs appear to be mediated through dopaminergic pathways, although other neurotransmitters, including γ-aminobutyric acid, serotonin, and norepinephrine, are also involved in mediating drug-induced reinforcement ( Chapter 27 ).
The Environment
The third critical factor in the development, maintenance, and perhaps cessation of drug use disorders is the environment in which the use occurs. Drug use does not occur in a vacuum. Rather, many societal factors, including legal status, availability, price, perception of dangerousness, social desirability, peer group, and religious beliefs, influence behavior relating to substance use. Drug availability is known to affect likelihood of substance use. For example, alcohol consumption ( Chapter 364 ) increases when the hours during which alcohol can be sold are extended. The restriction of alcohol availability by restricting hours of sale or by increasing its cost through taxation in turn reduces consumption. Illicit drugs are, of course, by definition less available than alcohol ( [CR] ) or tobacco ( Chapter 363 ). A major factor that influences use of these agents is the potential user’s perception of the drug’s safety, social cachet (or lack thereof), likelihood of incurring legal consequences, and peer group behavior.
Clinical Manifestations
Medical Complications Related to Drug Use Disorders
The medical complications of drug use disorders are often directly related to the pharmacology of the drug being used (e.g., the vasoconstrictive properties of cocaine). In addition to these drug-specific sequelae, however, many medical complications occur as a result of three factors that cut across many misused drugs: paraphernalia, particularly unsterile needles; adulterants; and lifestyle issues.
Paraphernalia
Some of the most serious medical problems that occur in individuals with drug use disorders are a result of the route of administration rather than of the actual drug being used. The use of unsterile needles, particularly if they are shared with other drug users, can lead to a variety of localized and systemic infections, some of which can be life-threatening. Skin infections and cellulitis are relatively common among injection drug users. Systemic infections related to needle use are often serious; individuals who inject drugs may develop infective endocarditis ( Chapter 61 ) or osteomyelitis ( Chapter 251 ). For example, between 2016 and 2018, one survey found that infection-related complications of injection opioid use increased by over 20%. Other serious infections among injection drug users include hepatitis B, hepatitis C ( Chapter 134 ), and HIV infection ( Chapter 353 ).
Adulterants
Drugs that are purchased and sold illicitly are often adulterated or “cut” with other similar-looking products, with the intention of increasing the dealer’s profit margin. For example, other white powdery substances are typically added to cocaine and heroin during the dealing process to dilute their purity. Some of these adulterants can in turn cause medical problems. At times, these complications occur because of the combined toxicity of the adulterant and the route of administration. For example, talc, which may be added to street heroin or be injected by individuals who crush talc-containing pharmaceutical tablets such as opioids, can cause granulomas in the lung or liver. Other common adulterants in street drugs include quinine (frequently used with heroin) and lidocaine or levamisole (often added to cocaine), but such toxic materials as strychnine and ground glass in street drugs can cause serious medical sequelae. The extremely powerful synthetic opioid fentanyl and its analogues, sold either as an adulterant (e.g., added to heroin) or as a substitute for other opioids, was estimated to be responsible for almost 75% of opioid overdose deaths in 2019.
Lifestyle Issues
Many patients who have drug use disorders expose themselves to multiple risks owing to intoxication, participating in dangerous illegal activities, and associating with potentially violent people. As a result, these individuals experience a high rate of traumatic injuries and are at greater risk of being victims of assault, homicide, or suicide. Suicide ( Chapter 362 ) is far more common among people with substance use disorders than among the general population, likely related to a combination of the effects of acute intoxication, the high prevalence of depression among these individuals, and the higher rate of antisocial personality disorder, which is associated with a propensity toward impulsiveness, risk taking, and violence. Intoxication, which can lead to motor vehicle crashes, is also a factor in about one third of pedestrians who are killed by motor vehicles
Diagnosis
It is often helpful to enlist the help of a family member or significant other (with the patient’s permission) in obtaining historical information. In some acute medical situations ( Chapter 96 ), drug screening can be critical for urgent diagnosis and therapy. In other situations, individuals may be screened after an event or periodically for performance issues. Routine questioning about potential unhealthy drug use is recommended by the U.S. Preventative Services Task Force, although there is no confirmed evidence on its benefit.
Treatment
General Treatment Principles
Since drug use disorders represent a heterogeneous group of disorders, treatment requires a careful medical, social, and psychiatric assessment, including a detailed substance use history and laboratory testing. Intoxication and withdrawal syndromes need to be treated acutely; longer-term treatment involves helping the patient reduce or ideally abstain from substance use and thus improve overall functioning.
For disorders of illicit drug use, medications approved by the U.S. Food and Drug Administration (FDA) are available only for opioid use disorders. As a result, behavioral treatments are critically important. Behavioral treatments of proven benefit include cognitive-behavioral therapy, motivational enhancement therapy, contingency management (also referred to as motivational incentive) therapy, 12-step facilitation therapy, and behavioral couples therapy. For example, offering an alternative positive reward (e.g., a voucher that can be exchanged for desired goods and services such as movie tickets or clothes) in response to abstaining from drugs may help individuals with drug use disorders overcome their craving and reduce substance use. In fact, this type of treatment approach, based on the use of motivational incentives for abstinence, is one of the most powerful treatment interventions available for the treatment of drug use disorders. In addition to professional treatment, peer support groups such as the 12-step–oriented Alcoholics or Narcotics Anonymous and non–12-step groups such as SMART Recovery can be extremely helpful in facilitating recovery from drug use problems.
Major Drugs
Opioids
Opioids are a core part of the medical pharmacopoeia, primarily because of their capacity to treat pain but also because of their antitussive and antidiarrheal properties. Unfortunately, opioids are also powerful euphoriants with a substantial abuse liability. Opioids can be divided into four categories: natural opium alkaloids, including opium, morphine, and codeine; semisynthetic derivatives of morphine, including heroin and oxycodone; synthetic opioids that are not derived from morphine, including methadone and fentanyl; and opioid-containing preparations, such as elixir of terpin hydrate.
Epidemiology
In the United States, opioid overdoses now account for about 75,000 annual deaths, representing about 75% of all overdose deaths, with about a nine-fold increase since 1999. From 1999 to 2010, prescription opioids accounted for increases in opioid overdoses, at which point heroin overdose deaths rapidly increased. Starting in 2014, illicitly produced synthetic fentanyl and its analogues were responsible for the rapid increase in overdose deaths and now represent nearly 75% of opioid overdose deaths.
Opioids are currently the most commonly misused prescription drugs. Most people who misuse opioid analgesics report that they initially obtained them from a doctor’s prescription or from a friend or relative who had been prescribed them. Other factors that have led to increasing use of heroin and then fentanyl include the decreased availability of prescription opioid analgesics, as well as the increased availability and relatively low cost of heroin and fentanyl.
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