Drug addiction is a disorder involving physical and psychological dependence on a drug or drugs and characterized by tolerance (the need to consume larger and larger amounts of the drug to feel its effects), physical symptoms if the drug is withdrawn, or both. Drug addiction poses serious health risks because of its long-term physical effects, disruption of family and work life, and the symptoms of drug withdrawal, which can range from highly unpleasant to fatal. In most cases, the disorder begins as drug abuse — the use of illegal drugs, or the use of a legal drug in excessive quantities or for purposes other than those for which it is intended — and progresses over time into addiction.

Symptoms and Effects

The signs of addiction and its physical and psychological effects depend on the particular drug involved. Some addictive drugs are legal substances used inappropriately, such as sedatives; others are illegal. Addiction to alcohol is known as alcohol dependence.

Central Nervous System Depressants
Popularly known as “downers,” these drugs include prescription medications such as sedatives, barbiturates (such as phenobarbital or secobarbital), hypnotic drugs (often used as sleeping aids), and antianxiety agents (such as the benzodiazepines, which include diazepam [Valium], chlordiazepoxide hydrochloride [Librium], and alprazolam [Xanax]). Inhalants, such as model glue and aerosol propellants, also depress the central nervous system. The effects of these drugs are similar to those of alcohol intoxication: coma or drowsiness, slurred speech, lack of coordination, impaired memory, confusion, tremor or poor muscle tone, agitation, paranoia (extreme suspicion or feelings of being persecuted or pursued), and inappropriate emotions. All of these drugs pose the risk of death from overdose.

Central Nervous System Stimulants
Stimulants accelerate body functions, producing agitation, rapid speech, irritability, difficulty concentrating, and often a pattern of heavy use for several days (called a “run”) followed by a physical and emotional letdown (a “crash”). The most commonly used addictive central nervous system stimulants are amphetamines (“speed”) and cocaine (“coke”).

Amphetamines, which can cause a euphoric state lasting for several hours, produce a very strong psychological dependence. Tolerance develops rapidly with repeated use, but the compulsion to use the drug remains. Since amphetamines produce less physical dependence than many other addictive substances, withdrawal causes fewer, milder symptoms.

Cocaine, which can be inhaled or injected as a powder or smoked in the form known as crack, releases hormones that raise body temperature, heart rate and blood pressure, producing a euphoria in which the person feels powerful, in control of his or her surroundings, and sexually energized. Although often regarded as a safe recreational chemical, cocaine is highly addictive and dangerous, carrying a risk of death from seizures, respiratory failure, stroke, cerebral hemorrhage (bleeding in the brain), or heart failure even with a modest dose. Addiction disrupts sleeping and eating patterns and is psychologically disturbing, causing irritability and diminishing the ability to concentrate.

Narcotics
Narcotics include drugs produced from the opium plant (the opiates, such as morphine and heroin) and synthetic compounds (opioids) such as codeine and methadone that mimic the effects of the opiates. Certain narcotics are used medically for pain control, anesthesia and cough suppression. People who abuse narcotics are most likely to use heroin, which is an illegal drug usually injected into a vein but may be smoked or snorted. Narcotics cause central nervous system depression, often with agitation; anxiety; impulsiveness; fear of failure; low self-esteem, hopelessness and aggression; reduced tolerance to frustration; inability to cope; and a need for immediate gratification. Narcotic users tend to associate with other people who abuse drugs. Inadequate sterilization of needles used to inject heroin can cause local or systemic infections, including tuberculosis, hepatitis, and HIV (human immunodeficiency virus) infection. Narcotics produce physical and psychological dependence.

Cannabis Compounds
The leaves and flowers of the marijuana plant (Cannabis sativa) are smoked in cigarettes and pipes, or they are cooked into brownies or other foods. Concentrated marijuana resin is made into hashish, which is usually smoked. The active agent in marijuana, delta-9-tetrahydrocannabinol or THC, is used for certain medical purposes and sometimes sold illegally. Smoking marijuana (called a “joint”) or hashish causes faster absorption than ingestion of the drug. Cannabis produces euphoria and relaxation, similar to moderate intoxication with alcohol. Thinking, perception, judgment and coordination are all impaired. There can be severe psychological effects, including paranoia (feelings of suspicion or persecution) and delirium (extreme agitation and confusion), in individuals who are mentally or emotionally unstable. People who are addicted to cannabis lose interest in everyday events and have little or no ambition to achieve even simple goals, such as holding a job. They can suffer from increased heart rate, conjunctivitis (eyes reddened by inflammation), and decreased lung function from smoking. Withdrawal symptoms include sweating, tremors, nausea, vomiting, diarrhea, irritability and difficulty sleeping (insomnia).

Treatment

Drug addiction can be treated with a variety of medical, behavioral and supportive therapies. The goals of treatment are to keep the person off the drug, to improve his or her ability to function, and to address the medical and social complications of drug addiction. Most programs begin with detoxification, a four- to seven-day medical process, usually in a hospital setting, in which a person addicted to drugs is withdrawn from the addictive substance under the care of a doctor. The goal of detoxification is to manage the symptoms of withdrawal and prevent serious medical problems. Following detoxification, the person can enter a treatment program. The type of treatment depends on the individual, the drug or drugs involved, and available resources. Short-term treatment programs last fewer than six months and include residential therapy (in which the individual lives in a special facility to receive treatment), medication therapy, and outpatient therapy. Outpatient therapy consists primarily of individual or group counseling.

Longer-term treatment programs last more than six months. The most common are methadone-maintenance treatments that involve giving a supportive dose of methadone to people addicted to heroin; the methadone blocks heroin’s effects but produces no euphoria. Therapeutic communities offer highly structured, residential treatment programs over a six- to 12-month period. These programs are particularly useful for people with long-term addictions.

Excerpted from: Complete Medical Encyclopedia, American Medical Association, 2003.