Substance use disorders involve a pathologic pattern of behaviors in which patients continue to use a substance despite experiencing significant problems related to its use. Diagnosis of substance use disorder is based on diagnostic criteria for the pattern of behaviors. Treating substance use disorder is challenging and varies depending on the substance and circumstances.
The common terms "addiction," "abuse," and "dependence" have often been used with regard to substance use, but these terms are too loosely and variably defined to be very useful in systematic diagnosis. "Substance use disorder" is more comprehensive and has fewer negative connotations. The substances involved are members of the 10 classes of drug that typically cause substance-related disorders.
Physiologic effects of substance use
These substances all directly activate the brain reward system and produce feelings of pleasure. The activation may be so intense that patients intensely crave the substance and neglect normal activities to obtain and use it. These substances also have direct physiologic effects, including
Intoxication
Withdrawal
Substance-induced psychiatric disorders
The specific manifestations and treatment of intoxication and withdrawal vary by the substance or substance class and are discussed elsewhere in THE MANUAL.
Intoxication
Intoxication refers to development of a reversible substance-specific syndrome of mental and behavioral changes that may involve altered perception, euphoria, cognitive impairment, impaired judgment, impaired physical and social functioning, mood lability, belligerence, or a combination. Taken to the extreme, intoxication can lead to overdose, significant morbidity, and risk of death.
Withdrawal
Withdrawal refers to substance-specific physiologic effects, symptoms, and behavioral changes that are caused by stopping or reducing the intake of a substance. To be classified as a substance-withdrawal disorder, the withdrawal syndrome must cause the patient significant distress and/or impair functioning (eg, social, occupational). Most patients with withdrawal recognize that readministering the substance will reduce their symptoms.
Although some patients with a withdrawal syndrome have a substance use disorder, some drugs, particularly opioids, sedative/hypnotics, and stimulants, can result in withdrawal symptoms even when taken as prescribed for legitimate medical reasons and for relatively brief periods (< 1 week for opioids). Withdrawal symptoms that develop following appropriate medical use are not considered criteria for diagnosis of a substance use disorder.
Substance-induced Psychiatric Disorders
Substance-induced psychiatric disorders are psychiatric changes produced by substance use or withdrawal that resemble independent psychiatric disorders (eg, depression, psychosis, anxiety, or neurocognitive disorders).
For a psychiatric disorder to be considered substance-induced, the substance involved must be known to be capable of causing the disorder. Substances can be members of the 10 classes of drug that typically cause substance-related disorders or many others (eg, anticholinergics and corticosteroids may cause temporary psychotic syndromes). In addition, the psychiatric disorder should
Appear within 1 month of substance intoxication or withdrawal
Cause significant distress or impaired functioning
Not have manifested before use of the substance
Not occur solely during acute delirium caused by the substance
Not persist for a substantial period of time*
* Certain neurocognitive disorders caused by alcohol, inhalants, or sedative-hypnotics and perceptual disorders caused by hallucinogens may be long-lasting.
Clinical Approach to Substance Use Disorders
Use of illegal drugs, although problematic because it is illegal, does not always involve a substance use disorder. Conversely, legal substances, such as alcohol and prescription drugs (and cannabis in an increasing number of US states), may be involved in a substance use disorder. Problems caused by use of prescription and illegal drugs cut across all socioeconomic groups.
Recreational drug use, although often not sanctioned by society, is not a new phenomenon, and has existed in some form or another for centuries. People have used drugs for a variety of reasons:
To alter or enhance mood
As part of religious ceremonies
To obtain spiritual enlightenment
To enhance performance
Etiology of Substance Use Disorders
People with a substance use disorder usually progress from experimentation to occasional use and then to heavy use and sometimes a substance use disorder. This progression is complex and only partially understood. The process depends on interaction between the drug, user, and setting.
Drug
Drugs in the 10 classes vary in how likely they are to cause a substance use disorder. The likelihood is termed addiction liability. Addiction liability depends upon a combination of factors including
Route of administration
Rate at which the drug crosses the blood-brain barrier and stimulates the reward pathway
Time to onset of effect
Ability to induce tolerance and/or withdrawal symptoms
In addition, substances that are legally and/or readily available (eg, alcohol, tobacco) are more likely to be used initially and thus increase the risk of progression to problematic use. Further, as perception of the risk in using a particular substance diminishes, there may be subsequent experimentation and/or recreational use of the drug, increasing exposures to substances of abuse. Fluctuations in perception of risk are influenced by multiple factors, including findings regarding medical and psychiatric sequelae of use and social outcomes.
During treatment of medical illness or following surgical or dental procedures, patients may be prescribed opioids. A substantial portion of these drugs go unused but may remain in the home, representing a significant source for children, adolescents, and adults who wish to use them for nonmedical purposes. In response, there has been increased emphasis on the need to
Prescribe opioid drugs in lower amounts more appropriate to the likely duration and severity of pain
Promote safe storage of leftover drugs
Expand prescription take-back programs
User
Predisposing factors in users include the following:
Psychologic characteristics
Circumstances and disorders
Psychologic characteristics are not clearly a strong factor, although people with low levels of self-control (impulsivity) or high levels of risk-taking and novelty-seeking may have an increased risk of developing substance use disorder. However, the concept of the addictive personality that has variously been described by some behavioral scientists has little scientific evidence to back it.
A number of circumstances and coexisting disorders appear to increase risk. For example, people who are sad, emotionally distressed, or socially alienated may find these feelings are temporarily relieved by a drug; this can lead to increased use and sometimes a substance use disorder. Patients with other, unrelated psychiatric disorders are at increased risk of developing a substance use disorder. Patients with chronic pain (eg, back pain, pain due to sickle cell disease, neuropathic pain, fibromyalgia) often take opioid drugs for relief; many subsequently develop a substance use disorder. However, in many of these patients, nonopioid drugs and other treatments can adequately relieve pain and suffering.
Addiction is likely a polygenic disorder. There are a number of genetic and epigenetic factors that impact addiction progression. Research regarding specific genetic abnormalities varies by the specific substance.
Pearls & Pitfalls
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Setting
Cultural and social factors are very important in initiating and maintaining (or relapsing to) substance use. Observing family members (eg, parents, older siblings) and peers using substances increases risk that people will begin using substances. Peers are a particularly powerful influence among adolescents (see Drug and Substance Use in Adolescents). People who are trying to stop using a substance find it much more difficult if they are around others who also use that substance.
Physicians may inadvertently contribute to harmful use of psychoactive drugs by overzealously prescribing them to relieve pain or stress. Many social factors, including mass media, contribute to patients' expectation that drugs should be used to relieve all distress.
Diagnosis of Substance Use Disorders
Diagnostic criteria
Diagnosis of substance use disorder is based on identifying a pathologic pattern of behaviors in which patients continue to use a substance despite experiencing significant problems related to its use. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM5-TR) gives 11 criteria divided into 4 categories. Individuals meeting 2 or more of these criteria within a 12-month period are considered to have a substance use disorder.
Impaired control over use
The person takes the substance in larger amounts or for a longer time than originally planned
The person desires to stop or cut down on use of the substance
The person spends substantial time obtaining, using, or recovering from the effects of the substance
The person has an intense desire (craving) to use the substance
Social impairment
The person fails to fulfill major role obligations at work, school, or home
The person continues to use the substance even though it causes (or worsens) social or interpersonal problems
The person gives up or reduces important social, occupational, or recreational activity because of substance use
Risky use
The person uses the substance in physically hazardous situations (eg, when driving or in dangerous social circumstances)
The person continues to use the substance despite knowing it is worsening a medical or psychologic problem
Pharmacologic symptoms
Tolerance: The person needs to progressively increase the drug dose to produce intoxication or the desired effect, or the effect of a given dose decreases over time
Withdrawal: Untoward physical effects occur when the drug is stopped or when it is counteracted by a specific antagonist
Note that some drugs, particularly opioids, sedative/hypnotics, and stimulants, can result in tolerance and/or withdrawal symptoms even when taken as prescribed for legitimate medical reasons and for relatively brief periods (< 1 week for opioids). Withdrawal symptoms that develop following such appropriate medical use do not count as criteria for diagnosis of a substance use disorder.
The severity of the substance use disorder is determined by the number of symptoms:
Mild: 2 to 3 criteria
Moderate: 4 to 5 criteria
Severe: ≥ 6 criteria
Treatment of Substance Use Disorders
Varies depending on substance and circumstances
Treating substance use disorder is challenging and includes one or more of the following:
Acute detoxification
Prevention and management of withdrawal
Cessation (or rarely, reduction) of use
Maintenance of abstinence
Different treatment phases may be managed with drugs and/or counseling and support. Specific measures and issues are discussed under the specific substance elsewhere in THE MANUAL, including Alcohol Use Disorders and Opioid Use Disorder.
Key Points
Substance use disorder involves a pathologic pattern of behaviors in which patients continue to use a substance despite experiencing significant problems related to its use.
Manifestations are categorized into impaired control over use, social impairment, risky use, and pharmacologic symptoms.
The terms "addiction," "abuse," and "dependence" are vague and value-laden; it is preferable to speak of "substance use disorders" and focus on the specific manifestations and their severity.
The consequences and treatment of substance use disorder vary greatly depending on the substance.
