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Definitions of substance use disorders, dependence and addiction

Is addiction a disease?


What types of substances are misused/abused?

Who is impacted by substance use disorders?

Consequences of substance use disorders

What is treatment?

Does treatment work?

How does treatment benefit society?

NIDA’s 13 Principles of Effective Treatment

What is recovery?

Key Terms in the Field


The Substance Abuse and Mental Health Administration (SAMHSA) defines substance use disorders as involving dependence on or abuse of alcohol and/or drugs including the nonmedical use of prescription drugs as described in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). Dependence indicates a more severe substance problem than abuse.1

The National Institute on Drug Abuse, on it’s Web site, NIDA for Teens, defines addiction as “a chronic, relapsing disease characterized by compulsive drug-seeking and abuse and by long-lasting chemical changes in the brain.”

The American Academy of Pain Medicine, the American Pain Society, and the American Society of Addiction Medicine recognize the following definitions and recommend their use.4

Addiction is a primary, chronic, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. It is characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving.

Physical Dependence
Physical dependence is a state of adaptation that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist.

Tolerance is a state of adaptation in which exposure to a drug induces changes that result in a decrease of one or more of the drug's effects over time.

  • In 2005, an estimated 22.2 million persons aged 12 or older were classified with substance dependence or abuse in the past year (9.1 percent of the population aged 12 or older).3

  • Of these, 3.3 million were classified with dependence on or abuse of both alcohol and illicit drugs, 3.6 million were dependent on or abused illicit drugs but not alcohol, and 15.4 million were dependent on or abused alcohol but not illicit drugs.3

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Is addiction a disease?

A new publication from NIDA explains how science is helping dispel common beliefs about addiction. Drugs, Brains, and Behavior - The Science of Addiction states, “Throughout much of the last century, scientists studying drug abuse labored in the shadows of powerful myths and misconceptions about the nature of addiction. When science began to study addictive behavior in the 1930s, people addicted to drugs were thought to be morally flawed and lacking in willpower. Those views shaped society's responses to drug abuse, treating it as a moral failing rather than a health problem, which led to an emphasis on punitive rather than preventative and therapeutic actions. Today, thanks to science, our views and our responses to drug abuse have changed dramatically. Groundbreaking discoveries about the brain have revolutionized our understanding of drug addiction, enabling us to respond effectively to the problem.”6

Numerous studies have demonstrated that chronic substance use changes the brain in fundamental ways that endure long after substance misuse and abuse has ended. NIDA’s Web site states, “Addiction is a real and complex disease similar to other chronic diseases such as type II diabetes, cancer and heart disease. Imaging studies have shown evidence of tissue malfunction in the brains of those with addiction. There is often a genetic factor, meaning it can run in families.” Like other chronic medical conditions, substance use disorders are medical conditions and can be treated effectively.2

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These statistics are taken from SAMHSA’s National Survey on Drug Use and Health

  • In 2005, an estimated 19.7 million Americans aged 12 or older were current illicit drug users, meaning they had used an illicit drug during the month prior to the survey interview. This represents 8.1 percent of the population aged 12 years old or older.

  • Marijuana was the most commonly used illicit drug (14.6 million past month users). In 2005, it was used by 74.2 percent of current illicit drug users.

  • Slightly more than half of Americans aged 12 or older reported being current drinkers of alcohol in the 2005 survey (51.8 percent). This translates to an estimated 126 million people.

  • More than one fifth (22.7 percent) of persons aged 12 or older participated in binge drinking at least once in the 30 days prior to the survey in 2005. This translates to about 55 million people.

  • In 2005, heavy drinking was reported by 6.6 percent of the population aged 12 or older (16 million people).

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What types of substances are misused and abused?
These statistics are taken from SAMHSA’s 2007 National Alcohol and Drug Addiction Recovery Month Kit


  • In 2005, as many as 18.7 million people were classified with dependence on or abuse of alcohol.

  • Rates of binge alcohol use were highest among people aged 21 to 23 in 2005.



  • Marijuana is the most commonly used illicit drug, with 14.6 million past-month users.

  • In 2005, among past-year marijuana users, 3.4 million people used marijuana on a daily or almost-daily basis.

  • There were 4.1 million people classified with dependence on or abuse of marijuana in 2005.


Cocaine and “Crack”1

  • Cocaine is a powerfully addictive stimulant that directly affects the brain.

  • One form of cocaine is hydrochloric salt, a white powder that dissolves in water and can be taken either intravenously or through the nose. The other form, freebase (crack), is cocaine that has not been neutralized by an acid and can be smoked.

  • In 2005, there were an estimated 2.4 million current cocaine users aged 12 or older. The average age at first-time use of cocaine was 19.7 years.


Ecstasy (MDMA)1

  • Ecstasy is a synthetic illicit drug that causes both hallucinogenic and stimulant effects. It is generally sold as a tablet to be taken orally.

  • In 2005, the average age of first using Ecstasy for those ages 12 to 49 was 20.7 years.



  • Hallucinogens, including lysergic acid diethylamide (LSD), mescaline, and psilocybin mushrooms, are drugs that disrupt a person’s ability to think and communicate rationally and can confuse one’s perception of reality.

  • Drugs such as phencyclidine (PCP) and ketamine, which were initially developed as general anesthetics for surgery, distort perceptions of sight and sound and produce feelings of detachment and dissociation from the environment and self.

  • In 2005, there were 953,000 people who used hallucinogens for the first time, including 243,000 people who used LSD for the first time.

  • The most common hallucinogen used in 2004 among teenagers was psilocybin mushrooms, also known as “‘shrooms.”


Prescription Drugs1

  • Nonmedical use of prescription drugs is defined as taking a higher-than-prescribed dose of a pharmaceutical, taking a pharmaceutical prescribed for another individual, malicious poisoning of another individual, or substance abuse involving pharmaceuticals.

  • In 2005, there were 6.4 million people who used prescription drugs nonmedically in the past month.

  • In 2005, the most prevalent source from which prescription drugs were obtained was “from a friend or relative for free.”

  • In 2004, almost 2 million people aged 12 or older met criteria for past-year dependence on or abuse of prescription drugs.

  • There were nearly a half-million estimated emergency department visits involving the nonmedical use of pharmaceuticals in 2004.


Central nervous system (CNS) depressants1

  • These drugs may be prescribed by physicians to treat anxiety and sleep disorders.

  • All CNS depressants work by slowing the brain’s activity.



  • Stimulants are used to increase alertness and physical activity.

  • In 2005, nearly 2.8 million people used stimulants nonmedically in the past year.

  • Methamphetamine/Amphetamines1

  • Methamphetamine (meth) and amphetamines are central nervous system stimulants. They can be consumed orally or by smoking, snorting, intravenous injection, or inhalation.

  • The widespread production, distribution, and use of meth affect urban, suburban, and rural communities nationwide.

  • In 2005, there were 512,000 current users of meth.



  • Heroin is processed from morphine. It can be injected, inhaled (snorted), or smoked.

  • Opioids are narcotics and include morphine, oxycodone, hydrocodone, and codeine. They are prescribed by physicians to treat pain from cancer, terminal illness, severe injury, or surgery.

  • In 2005, there were 136,000 current heroin users.



  • The term “inhalants” refers to more than 1,000 different household and commercial products that can be intentionally misused by inhaling them through the mouth or nose for an intoxicating effect.

  • In 2005, 877,000 people used inhalants for the first time; 72.3 percent were under age 18 when they first used them.


Anabolic Steroids1

  • Anabolic steroids are synthetic derivatives of the male hormone testosterone. They promote the growth of skeletal muscle and the development of male sexual characteristics.

  • Steroids can be taken orally or via needle injection.23

  • It is estimated that hundreds of thousands of people aged 18 and older misuse steroids at least once a year.



  • Researchers have identified more than 4,800 chemical compounds in tobacco smoke; of these, at least 69 cause cancers in humans and animals.

  • An estimated 71.5 million Americans were current users of a tobacco product in 2005:  60.5 million people smoked cigarettes, 13.6 million people smoked cigars, 7.7 million people used smokeless tobacco, and 2.2 million people smoked tobacco in pipes.

  • Young adults aged 18 to 25 had the highest rate of current use of a tobacco product at 44.3 percent.

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Who is impacted by substance use disorders?

Substance use disorders impact every sector of society. All races, cultures, ages and genders are affected. SAMHSA states, “Substance use disorders are still a major health problem that impacts society on multiple levels. They cost our nation more than $484 billion per year in health care expenditures, lost earnings, and costs associated with crime and accidents.”1 Therefore, everyone, either directly or indirectly, is impacted by the burdens related to substance use disorders. 

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Consequences of Substance Use Disorders

“In 2001, the total expenditure for the treatment of substance use disorders in the United States was $18 billion. Another way of measuring costs is by calculating the total economic costs, including the costs of medical consequences of alcohol and drug use, lost earnings linked to premature death, lost productivity, motor vehicle crashes, crime, and other social consequences. Additionally, more than 26,000 people died of drug-induced causes and nearly 20,000 died of alcohol-induced causes in the United States in 2002.”1

NIDA indicates that America’s top medical problems can be directly linked to drug abuse5

  • Tobacco contributes to 11-30% of cancer deaths.

  • Researchers have found a connection between the abuse of tobacco, cocaine, MDMA (ecstasy), amphetamines, and steroids to the development of cardiovascular disease. Tobacco is responsible for approximately 30% of all heart disease deaths each year.

  • About one-third of AIDS cases reported in 2000, and most cases of Hepatitis C are associated with injection drug use. Approximately half of pediatric AIDS cases result from injection drug use or sex with injection drug users by the child’s mother.

NIDA also indicates that many of America's top social problems also relate to or impact drug abuse5

  • The National Highway Traffic Safety Administration estimates that drugs are used by approximately 10 to 22 percent of drivers involved in crashes, often in combination with alcohol.

  • At least half of the individuals arrested for major crimes including homicide, theft, and assault were under the influence of illicit drugs around the time of their arrest.

  • At least two-thirds of patients in drug abuse treatment centers say they were physically or sexually abused as children.

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What is treatment?

SAMHSA defines treatment as “a path of recovery that can involve many interventions and attempts at abstinence. It is offered in different settings, and types of treatment greatly depend on the substances misused, as well as a person’s individual needs and characteristics. Treatment is offered in residential and outpatient programs and can include counseling or other behavioral therapy, family therapy, medication, or a combination of services.”1

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Does treatment work?

Research shows that substance use disorders are medical conditions that can be effectively treated, just as many illnesses are treatable. SAMHSA notes, “A major study published in 2000 in the Journal of the American Medical Association is one of several that demonstrate the effectiveness of treatment for substance use disorders. The study found that treatments for drug use disorders are just as effective as treatments for other chronic conditions, such as high blood pressure, asthma, and diabetes.”1

NIDA indicates that relapse does not mean that treatment has failed. “The chronic nature of the disease means that relapsing to drug abuse is not only possible, but likely, with relapse rates similar to those for other well-characterized chronic medical illnesses such as diabetes, hypertension, and asthma, which also have both physiological and behavioral components. Treatment of chronic diseases involves changing deeply imbedded behaviors, and relapse does not mean treatment failure. For the addicted patient, lapses back to drug abuse indicate that treatment needs to be reinstated or adjusted, or that alternate treatment is needed.”6

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How does treatment benefit society?

Recent cost benefit studies consistently find that benefits to society of addiction treatment are greater than the costs of addiction treatment. As people participate in treatment and find recovery there is reduced crime, improved health, lower health care costs and improved employment and social functioning. Helping one person achieve recovery from a substance use disorder through effective treatment programs and other support services can improve many lives.

Materials from SAMHSA’s 2007 Recovery Month campaign say, “Many studies show a positive return on investment when money is spent on treatment. Research suggests at least a 2:1 benefit-to-cost ratio, with other studies allowing for a return of $7 for every dollar spent on treatment.Another study discovered as much as a $23 return for every dollar spent on treatment.While the return on investment varies from state to state and program to program, evidence supports the overall positive financial gain to society when investing in the treatment of people with substance use disorders. … Research has consistently found that people who have untreated substance use disorders typically have high rates of repeated contacts with the justice system and a greater chance of re-incarceration. However, when inmates receive treatment for a substance use disorder, re-arrests have shown to drop from 75 percent to 27 percent.”1

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NIDA’s 13 Principles of Effective Treatment

A 1999 publication from the National Institute on Drug Abuse called Principles of Drug Addiction Treatment: A Research Based Guide, highlights 13 overarching principles that define effective drug treatment. A brief description of each principle is listed below.10
    1. No single treatment is appropriate for all individuals. Matching treatment settings, interventions, and services to each individual's particular problems and needs is critical to his or her ultimate success in returning to productive functioning in the family, workplace and society.

    2. Treatment needs to be readily available. Because individuals who are addicted to drugs may be uncertain about entering treatment, taking advantage of opportunities when they are ready for treatment is crucial. Potential treatment applicants can be lost if treatment is not immediately available or is not readily accessible.

    3. Effective treatment attends to multiple needs of the individual, not just his or her drug use. To be effective, treatment must address the individual's drug use and any associated medical, psychological, social, vocational, and legal problems.

    4. An individual's treatment and services plan must be assessed continually and modified as necessary to ensure that the plan meets the person's changing needs. A patient may require varying combinations of services and treatment components during the course of treatment and recovery. In addition to counseling or psychotherapy, a patient at times may require medication, other medical services, family therapy, parenting instruction, vocational rehabilitation, and social and legal services. It is critical that the treatment approach be appropriate to the individual's age, gender, ethnicity, and culture.

    5. Remaining in treatment for an adequate period of time is critical for treatment effectiveness. The appropriate duration for an individual depends on his or her problems and needs. Research indicates that for most patients, the threshold of significant improvement is reached at about 3 months in treatment. After this threshold is reached, additional treatment can produce further progress toward recovery. Because people often leave treatment prematurely, programs should include strategies to engage and keep patients in treatment.

    6. Counseling (individual and/or group) and other behavioral therapies are critical components of effective treatment for addiction. In therapy, patients address issues of motivation, build skills to resist drug use, replace drug-using activities with constructive and rewarding nondrug-using activities, and improve problem-solving abilities. Behavioral therapy also facilitates interpersonal relationships and the individual's ability to function in the family and community. (Approaches to Drug Addiction Treatment section discusses details of different treatment components to accomplish these goals.)

    7. Medications are an important element of treatment for many patients, especially when combined with counseling and other behavioral therapies. Methadone and levo-alpha-acetylmethadol (LAAM) are very effective in helping individuals addicted to heroin or other opiates stabilize their lives and reduce their illicit drug use. Naltrexone is also an effective medication for some opiate addicts and some patients with co-occurring alcohol dependence. For persons addicted to nicotine, a nicotine replacement product (such as patches or gum) or an oral medication (such as bupropion) can be an effective component of treatment. For patients with mental disorders, both behavioral treatments and medications can be critically important.

    8. Addicted or drug-abusing individuals with coexisting mental disorders should have both disorders treated in an integrated way. Because addictive disorders and mental disorders often occur in the same individual, patients presenting for either condition should be assessed and treated for the co-occurrence of the other type of disorder.

    9. Medical detoxification is only the first stage of addiction treatment and by itself does little to change long-term drug use. Medical detoxification safely manages the acute physical symptoms of withdrawal associated with stopping drug use. While detoxification alone is rarely sufficient to help addicts achieve long-term abstinence, for some individuals it is a strongly indicated precursor to effective drug addiction treatment (see Drug Addiction Treatment Section).

    10. Treatment does not need to be voluntary to be effective. Strong motivation can facilitate the treatment process. Sanctions or enticements in the family, employment setting, or criminal justice system can increase significantly both treatment entry and retention rates and the success of drug treatment interventions.

    11. Possible drug use during treatment must be monitored continuously. Lapses to drug use can occur during treatment. The objective monitoring of a patient's drug and alcohol use during treatment, such as through urinalysis or other tests, can help the patient withstand urges to use drugs. Such monitoring also can provide early evidence of drug use so that the individual's treatment plan can be adjusted. Feedback to patients who test positive for illicit drug use is an important element of monitoring.

    12. Treatment programs should provide assessment for HIV/AIDS, hepatitis B and C, tuberculosis and other infectious diseases, and counseling to help patients modify or change behaviors that place themselves or others at risk of infection. Counseling can help patients avoid high-risk behavior. Counseling also can help people who are already infected manage their illness.

    13. Recovery from drug addiction can be a long-term process and frequently requires multiple episodes of treatment. As with other chronic illnesses, relapses to drug use can occur during or after successful treatment episodes. Addicted individuals may require prolonged treatment and multiple episodes of treatment to achieve long-term abstinence and fully restored functioning. Participation in self-help support programs during and following treatment often is helpful in maintaining abstinence. 

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What is Recovery?

SAMHSA defines recovery from alcohol and drug problems as “a process of change through which an individual achieves abstinence and improved health, wellness, and quality of life.”

The distinction between treatment and recovery is important. The Recovery Services Community Programs Web site explains that “recovering from alcohol and drug use disorders is a highly individualized experience, and everyone who goes through the experience has an individual definition of recovery. In addition, recovery is achieved via many different pathways.  Within the RCSP projects, an emerging definition goes beyond abstinence alone to include a full re-engagement—based on resilience, health, and hope—with one’s family, friends, and community.”

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