Contents Preface Preface How Science Has Revolutionized the Understanding of Drug Addiction For much of the past century, scientists studying drugs and drug use labored in the shadows of powerful myths and misconceptions about the nature of addiction. When scientists 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 use, treating it as a moral failing rather than a health problem, which led to an emphasis on punishment rather than prevention and treatment. Today, thanks to science, our views and our responses to addiction and the broader spectrum of substance use disorders have changed dramatically. Groundbreaking discoveries about the brain have revolutionized our understanding of compulsive drug use, enabling us to respond effectively to the problem. As a result of scientific research, we know that addiction is a medical disorder that affects the brain and changes behavior. We have identified many of the biological and environmental risk factors and are beginning to search for the genetic variations that contribute to the development and progression of the disorder. Scientists use this knowledge to develop effective prevention and treatment approaches that reduce the toll drug use takes on individuals, families, and communities. Despite these advances, we still do not fully understand why some people become addicted to drugs or how drugs change the brain to foster compulsive drug use. This booklet aims to fill that knowledge gap by providing scientific information about the disorder of drug addiction, including the many harmful consequences of drug use and the basic approaches that have been developed to prevent and treat substance use disorders. At the National Institute on Drug Abuse (NIDA), we believe that increased understanding of the basics of addiction will empower people to make informed choices in their own lives, adopt science-based policies and programs that reduce drug use and addiction in their communities, and support scientific research that improves the Nation’s well-being. Nora D. Volkow, M.D. Go to Top Introduction Why study drug use and addiction? Use and misuse of alcohol, nicotine, and illicit drugs, and misuse of prescription drugs cost Americans more than $700 billion a year in increased health care costs, crime, and lost productivity.1,2,3 Every year, illicit and prescription drugs and alcohol contribute to the death of more than 90,000 Am ericans, while tobacco is linked to an estimated 480,000 deaths per year.4,5 (Hereafter, unless otherwise specified, drugs refers to all of these substances.) People of all ages suffer the harmful consequences of drug use and addiction:
How does science provide solutions for drug use and addiction? Scientists study the effects drugs have on the brain and behavior. They use this information to develop programs for preventing drug use and for helping people recover from addiction. Further research helps transfer these ideas into practice in the community. The consequences of drug use are vast and varied and affect people of all ages. Go to Top Drug Misuse and Addiction What is drug addiction? Addiction is defined as a chronic, relapsing disorder characterized by compulsive drug seeking and use despite adverse consequences.† It is considered a brain disorder, because it involves functional changes to brain circuits involved in reward, stress, and self-control, and those changes may last a long time after a person has stopped taking drugs.11 Addiction is a lot like other diseases, such as heart disease. Both disrupt the normal, healthy functioning of an organ in the body, both have serious harmful effects, and both are, in many cases, preventable and treatable. If left untreated, they can last a lifetime and may lead to death. Source: Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health. Modified with permission from Volkow et al. 1993. Note: These fMRI images compare the brain of an individual with a history of cocaine use disorder (middle and right) to the brain of an individual without a history of cocaine use (left). The person who has had a cocaine use disorder has lower levels of the D2 dopamine receptor (depicted in red) in the striatum one month (middle) and four months (right) after stopping cocaine use compared to the non-user. The level of dopamine receptors in the brain of the cocaine user are higher at the 4-month mark (right), but have not returned to the levels observed in the non-user (left). †The term addiction as used in this booklet is equivalent to a severe substance use disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5, 2013). Why do people take drugs? In general, people take drugs for a few reasons:
If taking drugs makes people feel good or better, what’s the problem? When they first use a drug, people may perceive what seem to be positive effects. They also may believe they can control their use. But drugs can quickly take over a person’s life. Over time, if drug use continues, other pleasurable activities become less pleasurable, and the person has to take the drug just to feel “normal.” They have a hard time controlling their need to take drugs even though it causes many problems for themselves and their loved ones. Some people may start to feel the need to take more of a drug or take it more often, even in the early stages of their drug use. These are the telltale signs of an addiction. Even relatively moderate drug use poses dangers. Consider how a social drinker can become intoxicated, get behind the wheel of a car, and quickly turn a pleasurable activity into a tragedy that affects many lives. Occasional drug use, such as misusing an opioid to get high, can have similarly disastrous effects, including overdose, and dangerously impaired driving. Do people freely choose to keep using drugs? The initial decision to take drugs is typically voluntary. But with continued use, a person’s ability to exert self-control can become seriously impaired; this impairment in self-control is the hallmark of addiction. Brain imaging studies of people with addiction show physical changes in areas of the brain that are critical to judgment, decision-making, learning and memory, and behavior control.12 These changes help explain the compulsive nature of addiction. Why do some people become addicted to drugs, while others do not? No single factor determines whether a person will become addicted to drugs. As with other diseases and disorders, the likelihood of developing an addiction differs from person to person, and no single factor determines whether a person will become addicted to drugs. In general, the more risk factors a person has, the greater the chance that taking drugs will lead to drug use and addiction. Protective factors, on the other hand, reduce a person’s risk. Risk and protective factors may be either environmental or biological. Risk Factors Protective Factors Aggressive behavior in childhood13,14 Good self-control15 Lack of parental supervision14,16 Parental monitoring and support16-18 Poor social skills13,17,18 Positive relationships17,19 Drug experimentation14,20,21 Good grades17,22 Availability of drugs at school21,23 School anti-drug policies17 Community poverty24,25 Neighborhood resources26 What biological factors increase risk of addiction? Biological factors that can affect a person’s risk of addiction include their genes, stage of development, and even gender or ethnicity. Scientists estimate that genes, including the effects environmental factors have on a person’s gene expression, called epigenetics, account for between 40 and 60 percent of a person’s risk of addiction.27 Also, teens and people with mental disorders are at greater risk of drug use and addiction than others.28 What environmental factors increase the risk of addiction? Children’s earliest interactions within the family are crucial to their healthy development and risk for drug use. Environmental factors are those related to the family, school, and neighborhood. Factors that can increase a person’s risk include the following:
What other factors increase the risk of addiction?
Images of Brain Development in health Children and Teens (Ages 5-20) As the brain matures, experiences prune excess neural connections while strengthening those that are used more often. Many scientists think that this process contributes to the steady reduction in gray matter volume seen during adolescence (depicted as the yellow to blue transition in the figure). As environmental forces help determine which connections will wither and which will thrive, the brain circuits that emerge become more efficient. However, this is a process that can cut both ways because not all tasks are desirable. The environment is like an artist who creates a sculpture by chipping away excess marble; and just like bad artists can produce bad art, environments with negative factors (like drugs, malnutrition, bullying, or sleep deprivation) can lead to efficient but potentially harmful circuits that conspire against a person’s well-being. The brain continues to develop into adulthood and undergoes dramatic changes during adolescence. One of the brain areas still maturing during adolescence is the prefrontal cortex—the part of the brain that allows people to assess situations, make sound decisions, and keep emotions and desires under control. The fact that this critical part of a teen’s brain is still a work in progress puts them at increased risk for making poor decisions, such as trying drugs or continuing to take them. Introducing drugs during this period of development may cause brain changes that have profound and long-lasting consequences. Go to Top Preventing Drug Misuse and Addiction: The Best Strategy Why is adolescence a critical time for preventing drug addiction? As noted previously, early use of drugs increases a person’s chances of becoming addicted. Remember, drugs change the brain—and this can lead to addiction and other serious problems. So, preventing early use of drugs or alcohol may go a long way in reducing these risks. Risk of drug use increases greatly during times of transition. For an adult, a divorce or loss of a job may increase the risk of drug use. For a teenager, risky times include moving, family divorce, or changing schools.35 When children advance from elementary through middle school, they face new and challenging social, family, and academic situations. Often during this period, children are exposed to substances such as cigarettes and alcohol for the first time. When they enter high school, teens may encounter greater availability of drugs, drug use by older teens, and social activities where drugs are used. A certain amount of risk-taking is a normal part of adolescent development. The desire to try new things and become more independent is healthy, but it may also increase teens’ tendencies to experiment with drugs. The parts of the brain that control judgment and decision-making do not fully develop until people are in their early or mid-20s; this limits a teen’s ability to accurately assess the risks of drug experimentation and makes young people more vulnerable to peer pressure.36 Because the brain is still developing, using drugs at this age has more potential to disrupt brain function in areas critical to motivation, memory, learning, judgment, and behavior control.12 So, it’s not surprising that teens who use alcohol and other drugs often have family and social problems, poor academic performance, health-related problems (including mental health conditions), and involvement with the juvenile justice system. Can research-based programs prevent drug addiction in youth? Yes. Scientists have developed a broad range of programs that positively alter the balance between risk and protective factors for drug use in families, schools, and communities. Studies have shown that research-based programs, such as described in NIDA’s Principles of Substance Abuse Prevention for Early Childhood: A Research-Based Guideand Preventing Drug Use among Children and Adolescents: A Research-Based Guide for Parents, Educators, and Community Leaders, can significantly reduce early use of tobacco, alcohol, and other drugs.37 Also, while many social and cultural factors affect drug use trends, when young people perceive drug use as harmful, they often reduce their level of use.38 How do research-based prevention programs work? National drug use surveys indicate some children are using drugs by age 12 or 13. Prevention is the best strategy. These prevention programs work to boost protective factors and eliminate or reduce risk factors for drug use. The programs are designed for various ages and can be used in individual or group settings, such as the school and home. There are three types of programs:
Young Brains Under Study Using cutting-edge imaging technology, scientists from the NIDA’s Adolescent Brain Cognitive Development (ABCD) Study will look at how childhood experiences, including use of any drugs, interact with each other and with a child’s changing biology to affect brain development and social, behavioral, academic, health, and other outcomes. As the only study of its kind, the ABCD study will yield critical insights into the foundational aspects of adolescence that shape a person’s future. These brain images show the reward-related circuity in the cortical and subcortical regions of the brain that tend to be more active when a child is successful at achieving a reward. While all of the images show the regions of the brain that are active to reward, the regions in yellow and red are the most active. Courtesy of the ABCD Study. Adapted from Casey et al., 2018. https://doi.org/10.1016/j.dcn.2018.03.001 Economics of Prevention Benefit-per-dollar cost ratios for evidence-based interventions range from small returns per dollar invested to more than $65 every dollar invested.39 Go to Top Drugs and the Brain Introducing the Human Brain The human brain is the most complex organ in the body. This three-pound mass of gray and white matter sits at the center of all human activity—you need it to drive a car, to enjoy a meal, to breathe, to create an artistic masterpiece, and to enjoy everyday activities. The brain regulates your body’s basic functions, enables you to interpret and respond to everything you experience, and shapes your behavior. In short, your brain is you—everything you think and feel, and who you are. How does the brain work? The brain is often likened to an incredibly complex and intricate computer. Instead of electrical circuits on the silicon chips that control our electronic devices, the brain consists of billions of cells, called neurons, which are organized into circuits and networks. Each neuron acts as a switch controlling the flow of information. If a neuron receives enough signals from other neurons connected to it, it “fires,” sending its own signal on to other neurons in the circuit. The brain is made up of many parts with interconnected circuits that all work together as a team. Different brain circuits are responsible for coordinating and performing specific functions. Networks of neurons send signals back and forth to each other and among different parts of the brain, the spinal cord, and nerves in the rest of the body (the peripheral nervous system). To send a message, a neuron releases a neurotransmitter into the gap (or synapse) between it and the next cell. The neurotransmitter crosses the synapse and attaches to receptors on the receiving neuron, like a key into a lock. This causes changes in the receiving cell. Other molecules called transporters recycle neurotransmitters (that is, bring them back into the neuron that released them), thereby limiting or shutting off the signal between neurons. How do drugs work in the brain? Drugs interfere with the way neurons send, receive, and process signals via neurotransmitters. Some drugs, such as marijuana and heroin, can activate neurons because their chemical structure mimics that of a natural neurotransmitter in the body. This allows the drugs to attach onto and activate the neurons. Although these drugs mimic the brain’s own chemicals, they don’t activate neurons in the same way as a natural neurotransmitter, and they lead to abnormal messages being sent through the network. Other drugs, such as amphetamine or cocaine, can cause the neurons to release abnormally large amounts of natural neurotransmitters or prevent the normal recycling of these brain chemicals by interfering with transporters. This too amplifies or disrupts the normal communication between neurons. What parts of the brain are affected by drug use? Drugs can alter important brain areas that are necessary for life-sustaining functions and can drive the compulsive drug use that marks addiction. Brain areas affected by drug use include:
Some drugs like opioids also affect other parts of the brain, such as the brain stem, which controls basic functions critical to life, such as heart rate, breathing, and sleeping explaining why overdoses can cause depressed breathing and death. How do drugs produce pleasure? Pleasure or euphoria—the high from drugs—is still poorly understood, but probably involves surges of chemical signaling compounds including the body’s natural opioids (endorphins) and other neurotransmitters in parts of the basal ganglia (the reward circuit). When some drugs are taken, they can cause surges of these neurotransmitters much greater than the smaller bursts naturally produced in association with healthy rewards like eating, music, creative pursuits, or social interaction. It was once thought that surges of the neurotransmitter dopamine produced by drugs directly caused the euphoria, but scientists now think dopamine has more to do with getting us to repeat pleasurable activities (reinforcement) than with producing pleasure directly. How does dopamine reinforce drug use? Our brains are wired to increase the odds that we will repeat pleasurable activities. The neurotransmitter dopamine is central to this. Whenever the reward circuit is activated by a healthy, pleasurable experience, a burst of dopamine signals that something important is happening that needs to be remembered. This dopamine signal causes changes in neural connectivity that make it easier to repeat the activity again and again without thinking about it, leading to the formation of habits. Just as drugs produce intense euphoria, they also produce much larger surges of dopamine, powerfully reinforcing the connection between consumption of the drug, the resulting pleasure, and all the external cues linked to the experience. Large surges of dopamine “teach” the brain to seek drugs at the expense of other, healthier goals and activities. Simple activities in everyday life can produce small bursts of neurotransmitters in the brain bringing pleasurable feelings. Drugs can hijack that process. Cues in a person’s daily routine or environment that have become linked with drug use because of changes to the reward circuit can trigger uncontrollable cravings whenever the person is exposed to these cues, even if the drug itself is not available. This learned “reflex” can last a long time, even in people who haven’t used drugs in many years. For example, people who have been drug free for a decade can experience cravings when returning to an old neighborhood or house where they used drugs. Like riding a bike, the brain remembers. Why are drugs more addictive than natural rewards? For the brain, the difference between normal rewards and drug rewards can be likened to the difference between someone whispering into your ear and someone shouting into a microphone. Just as we turn down the volume on a radio that is too loud, the brain of someone who misuses drugs adjusts by producing fewer neurotransmitters in the reward circuit, or by reducing the number of receptors that can receive signals. As a result, the person’s ability to experience pleasure from naturally rewarding (i.e., reinforcing) activities is also reduced. This is why a person who misuses drugs eventually feels flat, without motivation, lifeless, and/or depressed, and is unable to enjoy things that were previously pleasurable. Now, the person needs to keep taking drugs to experience even a normal level of reward—which only makes the problem worse, like a vicious cycle. Also, the person will often need to take larger amounts of the drug to produce the familiar high—an effect known as tolerance. Long-term drug use impairs brain functioning. For more information on drugs and the brain, order NIDA’s Teaching Packets or the Mind Matters series at www.drugabuse.gov/parent-teacher.html. These items and others are available to the public free of charge. Go to Top Addiction and Health What are the other health consequences of drug addiction? People with addiction often have one or more associated health issues, which could include lung or heart disease, stroke, cancer, or mental health conditions. Imaging scans, chest X-rays, and blood tests can show the damaging effects of long term drug use throughout the body. For example, it is now well-known that tobacco smoke can cause many cancers, methamphetamine can cause severe dental problems, known as “meth mouth,” and that opioids can lead to overdose and death. In addition, some drugs, such as inhalants, may damage or destroy nerve cells, either in the brain or the peripheral nervous system (the nervous system outside the brain and spinal cord). Drug use can also increase the risk of contracting infections. Human immunodeficiency virus (HIV) and hepatitis C (a serious liver disease) infection can occur from sharing injection equipment and from impaired judgment leading to unsafe sexual activity.40,41 Infection of the heart and its valves (endocarditis) and skin infection (cellulitis) can occur after exposure to bacteria by injection drug use.42 Addiction and HIV/AIDS are intertwined epidemics. Does drug use cause mental disorders, or vice versa? Drug use and mental illness often co-exist. In some cases, mental disorders such as anxiety, depression, or schizophrenia may come before addiction; in other cases, drug use may trigger or worsen those mental health conditions, particularly in people with specific vulnerabilities.43,44 Some people with disorders like anxiety or depression may use drugs in an attempt to alleviate psychiatric symptoms, which may exacerbate their mental disorder in the long run, as well as increase the risk of developing addiction.43,44 Treatment for all conditions should happen concurrently. How can addiction harm other people? The Impact of Addiction Can Be Far-Reaching
Beyond the harmful consequences for the person with the addiction, drug use can cause serious health problems for others. Some of the more severe consequences of addiction are:
Go to Top Treatment and Recovery Can addiction be treated successfully? Yes, addiction is a treatable disorder. Research on the science of addiction and the treatment of substance use disorders has led to the development of research-based methods that help people to stop using drugs and resume productive lives, also known as being in recovery. Can addiction be cured? Like other chronic diseases such as heart disease or asthma, treatment for drug addiction usually isn’t a cure. But addiction can be managed successfully. Treatment enables people to counteract addiction’s disruptive effects on their brain and behavior and regain control of their lives. These images showing the density of dopamine transporters in the brain illustrate the brain’s remarkable ability to recover, at least in part, after a long abstinence from drugs—in this case, methamphetamine.51 Source: The Journal of Neuroscience, 21(23):9414-9418. 2001 Does relapse to drug use mean treatment has failed? No. The chronic nature of addiction means that for some people relapse, or a return to drug use after an attempt to stop, can be part of the process, but newer treatments are designed to help with relapse prevention. Relapse rates for drug use are similar to rates for other chronic medical illnesses. If people stop following their medical treatment plan, they are likely to relapse. Treatment of chronic diseases involves changing deeply rooted behaviors, and relapse doesn’t mean treatment has failed. When a person recovering from an addiction relapses, it indicates that the person needs to speak with their doctor to resume treatment, modify it, or try another treatment.52 Source: JAMA, 284:1689-1695, 2000. Relapse rates for people treated for substance use disorders are compared with those for people treated for high blood pressure and asthma. Relapse is common and similar across these illnesses. Therefore, substance use disorders should be treated like any other chronic illness. Relapse serves as a sign for resumed, modified, or new treatment. While relapse is a normal part of recovery, for some drugs, it can be very dangerous—even deadly. If a person uses as much of the drug as they did before quitting, they can easily overdose because their bodies are no longer adapted to their previous level of drug exposure. An overdose happens when the person uses enough of a drug to produce uncomfortable feelings, life-threatening symptoms, or death. What are the principles of effective treatment? Research shows that when treating addictions to opioids (prescription pain relievers or drugs like heroin or fentanyl), medication should be the first line of treatment, usually combined with some form of behavioral therapy or counseling. Medications are also available to help treat addiction to alcohol and nicotine. Additionally, medications are used to help people detoxify from drugs, although detoxification is not the same as treatment and is not sufficient to help a person recover. Detoxification alone without subsequent treatment generally leads to resumption of drug use. For people with addictions to drugs like stimulants or cannabis, no medications are currently available to assist in treatment, so treatment consists of behavioral therapies. Treatment should be tailored to address each patient’s drug use patterns and drug-related medical, mental, and social problems. Discoveries in science lead to breakthroughs in drug use treatment. What medications and devices help treat drug addiction? Different types of medications may be useful at different stages of treatment to help a patient stop abusing drugs, stay in treatment, and avoid relapse.
Common medications used to treat drug addiction and withdrawal
How do behavioral therapies treat drug addiction? Behavioral therapies help people in drug addiction treatment modify their attitudes and behaviors related to drug use. As a result, patients are able to handle stressful situations and various triggers that might cause another relapse. Behavioral therapies can also enhance the effectiveness of medications and help people remain in treatment longer.
Treatment must address the whole person. How do the best treatment programs help patients recover from addiction? Stopping drug use is just one part of a long and complex recovery process. When people enter treatment, addiction has often caused serious consequences in their lives, possibly disrupting their health and how they function in their family lives, at work, and in the community. Because addiction can affect so many aspects of a person’s life, treatment should address the needs of the whole person to be successful. Counselors may select from a menu of services that meet the specific medical, mental, social, occupational, family, and legal needs of their patients to help in their recovery. For more information on drug treatment, see
Principles of Drug Addiction Treatment: A Research-Based Guide, and Principles of Adolescent Substance Use Disorder Treatment: A Research-Based Guide. Go to Top Advancing Addiction Science and Practical Solutions Leading the Search for Scientific Solutions To address all aspects of drug use and its harmful consequences, NIDA’s research program ranges from basic studies of the addicted brain and behavior to clinical strategies and health services research. NIDA’s research program develops prevention and treatment approaches and ensures they work in real-world settings. As part of this goal, NIDA is committed to research that addresses the vulnerabilities and health differences that exist among ethnic minorities or that stem from gender differences. Bringing Science to Real-World Settings
Sharing Free Information With the Public NIDA increases the impact of its research on addiction by sharing free information with professionals and the general public. Special initiatives are intended for researchers, clinicians, educators, students, and parents. Please visit https://drugpubs.drugabuse.gov. NIDA’s Special Initiatives for Students, Teachers, and Parents
Special Initiative for Clinicians NIDAMED – A collection of resources for health professionals on the causes and consequences of drug use and addiction, and advances in pain management. Publications on Prevention and Treatment Principles Preventing Drug Use among Children and Adolescents: A Research-Based Guide for Parents, Educators, and Community Leaders – NIDA’s research-based guide for preventing drug use among children and adolescents provides principles based on effective drug-prevention research and includes answers to questions on risk and protective factors as well as on community planning and implementation Principles of Drug Addiction Treatment: A Research-Based Guide – This guide summarizes principles of effective treatment, answers common questions, and describes types of treatment, providing examples of scientifically based and tested treatment components Principles of Adolescent Substance Use Disorder Treatment: A Research-Based Guide – This guide discusses the urgency of treating substance use disorders in teenagers, answers common questions about how young people are treated for drug problems, and describes effective research-based treatment approaches Principles of Drug Abuse Treatment for Criminal Justice Populations: A Research-Based Guide – NIDA’s research-based guide for treating criminal justice-involved people with addiction provides essential treatment principles and includes answers to frequently asked questions as well as resource information. For more information: All NIDA publications are available at www.drugabuse.gov. Some publications are also available in print, free of charge. To order a publication in print, call the DRUGPubs Research Dissemination Center at 1–877–NIH–NIDA or go to drugpubs.drugabuse.gov. Watch NIDA videos (NIDA TV) at:
www.drugabuse.gov/nida-tv. Go to Top References
From National Institute on Drug Abuse |