- Also called:
- drug dependence or physical dependence
chemical dependence
What is chemical dependence?
How is dependence different from tolerance?
Is withdrawal a sign of dependence?
What kinds of prescribed drugs can lead to dependence?
chemical dependence, adaptation of the body to ongoing exposure to a drug or other substance. The risk of dependence is associated particularly with the use ofalcohol, benzodiazepines, nicotine, opioids, and other psychoactive substances and medications. Abruptly terminating the use of such substances, or even reducing the amount used, can induce various physical and psychological symptoms of withdrawal.
Dependence is distinct from addiction. Dependency on a medication can occur while an individual is taking it as prescribed and in the absence of seeking out or using the drug compulsively. Addiction, on the other hand, generally is characterized by a pattern of use that the individual follows, regardless of harmful consequences. Such behavior, which often is diagnosed as a substance use disorder, typically also includes difficulty controlling use. Dependence and addiction can occur together, but dependency on its own does not necessarily imply addiction.
Dependence and tolerance
Various body systems, and especially the nervous system, readily adapt to repeated exposure to certain substances. Such adaptations persist for a short window of time even when use is suddenly halted. Thus, in the period of time that the body requires to readjust to the absence of the substance, withdrawal symptoms are likely to occur.
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Dependence frequently is accompanied by tolerance. Tolerance is a distinct phenomenon, however, developing specifically when repeated exposure reduces the body’s response to a given dose; hence, it is not a prerequisite for physical dependence. As a consequence of tolerance, increasingly larger doses are required to produce the same effect. Some drugs very readily facilitate the development of tolerance, whereas others do not..
Withdrawal
The type of substance, along with its dose and duration of use, generally determine the characteristics of withdrawal. Withdrawal from opioids, for example, can cause anxiety, diarrhea, insomnia, nausea, restlessness, and sweating. In the case of withdrawal from nicotine, an individual is likely to experience difficulty concentrating, increased appetite, and irritability. Withdrawal symptoms may be so unpleasant as to cause an individual to use the substance again, simply to relieve the discomfort.
Some substances are accompanied by more serious and potentially dangerous effects. Examples include alcohol and certain sedatives, especially benzodiazepines. In severe cases, withdrawal may induce confusion, hallucinations, and seizures.
Treatment
Some medications and substances are discontinued in controlled settings or through programs designed for gradual discontinuation. For example, when dependence develops over the course of prescription medication use, the dose may be gradually tapered under physician supervision. In this way, the body is given time to readjust, with less severe withdrawal symptoms.
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In the presence of addiction, withdrawal is managed alongside other necessary components of treatment. Thus, depending on the substance, treatment can range from the use of specialized medications, behavioral therapies, counseling, and ongoing support, such as through recovery programs. Buprenorphine and methadone are examples of medications are used to treat opioid use disorder; they act by decreasing the intensity of cravings and stabilizing opioid activity in the body. Physical dependence is still a risk with these medications, but individuals are at lower risk of opioid overdose and are more likely to recover from opioid use disorder.
Terminating substance use and managing withdrawal is sometimes referred to by the term detoxification, or detox. This process, however, does not address the critical features that fuel addiction, and therefore other treatments generally are required to fully address substance use disorder.