National Institutes of Health

U.S. Department of Health 

and Human Services

THE SCIENCE OF ADDICTION

DRUGS,

BRAINS,

AND BEHAVIOR

THE SCIENCE OF ADDICTION

DRUGS,

BRAINS,

AND BEHAVIOR
This publication is in the public domain and may be used or reproduced in its entirety 

without permission from NIDA. Citation of the source is appreciated.

NIH Pub No. 07-5605

Printed April 2007

Reprinted February 2008
Preface............................................................................................................................................................................ 1

Introduction.................................................................................................................................................................... 3

I. Drug Abuse and Addiction ........................................................................................................................................... 5

II. Preventing Drug Abuse: The Best Strategy................................................................................................................. 11

III. Drugs and the Brain................................................................................................................................................ 15

IV. Addiction and Health................................................................................................................................................ 21

V. Treatment and Recovery ............................................................................................................................................ 25

VI. Advancing Addiction Science and Practical Solutions............................................................................................... 29

I

CONTENTS
“Drug addiction is a brain disease that can be treated.”

Nora D. Volkow, M.D.

Director

National Institute on Drug Abuse
How Science Has Revolutionized the Understanding of Drug Addiction

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. 

As a result of scientific research, we know that addiction is a disease that affects both brain and behavior. We have identified many of 

the biological and environmental factors and are beginning to search for the genetic variations that contribute to the development and 

progression of the disease. Scientists use this knowledge to develop effective prevention and treatment approaches that reduce the toll drug

abuse takes on individuals, families, and communities. 

Despite these advances, many people today do not understand why individuals become addicted to drugs or how drugs change the brain 

to foster compulsive drug abuse. This booklet aims to fill that knowledge gap by providing scientific information about the disease of drug

addiction, including the many harmful consequences of drug abuse and the basic approaches that have been developed to prevent and treat

the disease. 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 abuse and addiction in

their communities, and support scientific research that improves the Nation’s well-being. 

Nora D. Volkow, M.D.

Director

1 National Institute on Drug Abuse

PREFACE
The consequences of drug abuse are vast and varied 

and affect people of all ages.

MEDICAL SOCIAL ECONOMIC CRIMINAL JUSTICE
Why study drug abuse and addiction?

Abuse and addiction to alcohol, nicotine, and illegal substances cost Americans upwards of half a trillion dollars a year, considering

their combined medical, economic, criminal, and social impact. Every year, abuse of illicit drugs and alcohol contributes to the

death of more than 100,000 Americans, while tobacco is linked to an estimated 440,000 deaths per year.

People of all ages suffer the harmful consequences of drug abuse and addiction.

❚ Babies exposed to legal and illegal drugs in the womb may be born premature and underweight. This drug exposure can slow 

the child’s intellectual development and affect behavior later in life.

❚ Adolescents who abuse drugs often act out, do poorly academically, and drop out of school. They are at risk of unplanned 

pregnancies, violence, and infectious diseases.

❚ Adults who abuse drugs often have problems thinking clearly, remembering, and paying attention. They often develop poor social 

behaviors as a result of their drug abuse, and their work performance and personal relationships suffer.

❚ Parents’ drug abuse often means chaotic, stress-filled homes and child abuse and neglect. Such conditions harm the well-being and 

development of children in the home and may set the stage for drug abuse in the next generation. 

How does science provide solutions for drug abuse and addiction?

Scientists study the effects that drugs have on the brain and on people’s behavior. They use this information to develop programs for 

preventing drug abuse and for helping people recover from addiction. Further research helps transfer these ideas into practice in our

communities.

3

INTRODUCTION

5

I. DRUG ABUSE AND ADDICTION

What is drug addiction? 

Addiction is defined as a chronic, relapsing brain 

disease that is characterized by compulsive drug 

seeking and use, despite harmful consequences. 

It is considered a brain disease because drugs change the

brain—they change its structure and how it works. These

brain changes can be long lasting, and can lead to the 

harmful behaviors seen in people who abuse drugs.

DECREASED BRAIN METABOLISM IN DRUG ABUSER

Healthy Brain Diseased Brain/Cocaine Abuser

DECREASED HEART METABOLISM IN 

HEART DISEASE PATIENT

Healthy Heart Diseased Heart

HIGH LOW

Addiction is similar to other diseases,

such as heart disease. Both disrupt the

normal, healthy functioning of the

underlying organ, have serious harmful

consequences, are preventable, treatable,

and if left untreated, can last a lifetime.

Source: From the laboratories of 

Drs. N. Volkow and H. Schelbert.
6

Why do people take drugs?

In general, people begin taking drugs for a variety of reasons:

❚ To feel good. Most abused drugs produce intense feelings of pleasure. This initial sensation of euphoria is followed by other effects, which 

differ with the type of drug used. For example, with stimulants such as cocaine, the “high” is followed by feelings of power, self-confidence, and

increased energy. In contrast, the euphoria caused by opiates such as heroin is followed by feelings of relaxation and satisfaction. 

❚ To feel better. Some people who suffer from social anxiety, stress-related disorders, and 

depression begin abusing drugs in an attempt to lessen feelings of distress. Stress can play a major

role in beginning drug use, continuing drug abuse, or relapse in patients recovering from addiction. 

❚ To do better. The increasing pressure that some individuals feel to chemically enhance or 

improve their athletic or cognitive performance can

similarly play a role in initial experimentation and

continued drug abuse. 

❚ Curiosity and “because others are doing it.”

In this respect adolescents are particularly vulnerable

because of the strong influence of peer pressure; they 

are more likely, for example, to engage in “thrilling” 

and “daring” behaviors.

Courtesy: Vivian Felsen
7

If taking drugs makes people feel

good or better, what’s the problem?

At first, people may perceive what seem to be positive effects

with drug use. They also may believe that they can control

their use; however, drugs can quickly take over their lives.

Consider how a social drinker can become intoxicated, put

himself behind a wheel and quickly turn a pleasurable activity

into a tragedy for him and others. Over time, if drug use 

continues, pleasurable activities become less pleasurable, 

and drug abuse becomes necessary for abusers to simply feel

“normal.” Drug abusers reach a point where they seek and

take drugs, despite the tremendous problems caused for

themselves and their loved ones. Some individuals may start to

feel the need to take higher or more frequent doses, even in

the early stages of their drug use.

Is continued drug abuse a 

voluntary behavior?

The initial decision to take drugs is mostly voluntary. However,

when drug abuse takes over, a person’s ability to exert self

control can become seriously impaired. Brain imaging studies

from drug-addicted 

individuals show physical 

changes in areas of the

brain that are critical to

judgment, decisionmaking,

learning and memory, and

behavior control. Scientists

believe that these changes

alter the way the brain

works, and may help

explain the compulsive

and destructive behaviors

of addiction. 

Risk Factors Domain Protective Factors

Early Aggressive Behavior Individual Self-Control

Poor Social Skills Individual Positive Relationships

Lack of Parental Supervision Family Parental Monitoring and Support

Substance Abuse Peer Academic Competence

Drug Availability School Anti-Drug Use Policies

Poverty Community Strong Neighborhood Attachment

EXAMPLES OF RISK AND PROTECTIVE FACTORS
No single factor determines whether a person 

8 will become addicted to drugs.

Why do some people become

addicted to drugs, while others 

do not? 

As with any other disease, vulnerability to addiction differs

from person to person. In general, the more risk factors

an individual has, the greater the chance that taking drugs

will lead to abuse and addiction. “Protective” factors

reduce a person’s risk of developing addiction. 

What factors determine if a 

person will become addicted?

No single factor determines whether a person will 

become addicted to drugs. The overall risk for addiction 

is impacted by the biological makeup of the individual—it can even be influenced by gender or ethnicity, his or her developmental stage, and the

surrounding social environment (e.g., conditions at home, at school, and in the neighborhood).

Which biological factors increase risk of addiction?

Scientists estimate that genetic factors account for between 40 and 60 percent of a person’s vulnerability to addiction, including the effects of 

environment on gene expression and function. Adolescents and individuals with mental disorders are at greater risk of drug abuse and addiction than

the general population.

■ Early use ■ Availability ■ Cost

■ Route of administration

■ Effect of drug itself

■ Genetics ■ Gender ■ Mental disorders

■ Chaotic home and abuse ■ Parent’s use and attitudes ■ Peer influences ■ Community attitudes ■ Poor school achievement

RISK FACTORS
Children’s earliest interactions within the family 

are crucial to their healthy development and 

risk for drug abuse. 9

What environmental factors increase 

the risk of addiction?

❚ Home and Family. The influence of the home environment 

is usually most important in childhood. Parents or older family

members who abuse alcohol or drugs, or who engage in criminal

behavior, can increase children’s risks of developing their own 

drug problems.

❚ Peer and School. Friends and acquaintances have the greatest

influence during adolescence. Drug-abusing peers can sway even

those without risk factors to try drugs for the first time. Academic

failure or poor social skills can put a child further at risk for 

drug abuse.

What other factors increase 

the risk of addiction?

❚ Early Use. Although taking drugs at any age can lead to addiction,

research shows that the earlier a person begins to use drugs the

more likely they are to progress to more serious abuse. This may

reflect the harmful effect that drugs can have on the developing

brain; it also may result from a constellation of early biological and

social vulnerability factors, including genetic susceptibility, mental

illness, unstable family relationships, and exposure to physical 

or sexual abuse. Still, the fact remains that early use is a strong

indicator of problems ahead, among them, substance abuse and

addiction.

❚ Method of Administration. Smoking a drug or injecting it into

a vein increases its addictive potential. Both smoked and injected

drugs enter the brain within seconds, producing a powerful rush 

of pleasure. However, this intense “high” can fade within a few 

minutes, taking the abuser down to lower, more normal levels. 

It is a starkly felt contrast, and scientists believe that this low 

feeling drives individuals to repeated drug abuse in an attempt to

recapture the high pleasurable state.
10

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 enables us to assess

situations, make sound decisions, and keep our emotions and

desires under control. The fact that this critical part of an 

adolescent’s brain is still a work-in-progress puts them at

increased risk for poor decisions (such as trying drugs or 

continued abuse). Thus, introducing drugs while the brain is

still developing may have profound and long-lasting consequences.

AGES 5 20

Prefrontal Cortex

SIDE VIEW

TOP VIEW

Blue represents maturing of brain areas.

Source: PNAS; 101:8174–8179. 2004.

IMAGES OF BRAIN DEVELOPMENT IN 

HEALTHY CHILDREN AND TEENS (AGES 5–20) 

Addiction is a developmental disease—

it typically begins in childhood or adolescence.
Why is adolescence a critical time for preventing drug addiction?

As noted previously, early use of drugs increases a person’s chances of more serious drug abuse and addiction. Remember, drugs

change brains—and this can lead to addiction and other serious problems. So preventing early use of drugs or alcohol may reduce

the risk of progressing to later abuse and addiction.

Risk of drug abuse increases greatly during times of transition, such as changing schools, moving, or divorce. If we can prevent drug abuse,

we can prevent drug addiction. In early adolescence, when children advance from elementary through middle school, they face new and

challenging social and academic situations. Often during this period, children are exposed to abusable substances such as cigarettes and

alcohol for the first time. When they enter high school, teens may encounter greater availability of drugs, drug abuse by older teens, and

social activities where drugs are used. 

At the same time, many behaviors that are a normal aspect of their development, such as the desire to do something new or risky, may

increase teen tendencies to experiment with drugs. Some teens may give in to the urging of drug-abusing friends to share the experience

with them. Others may think that taking drugs (such as steroids) will improve their appearance or their athletic performance or that 

abusing substances such as alcohol or Ecstasy (MDMA) will ease their anxiety in social situations. 

Teens’ still-developing judgment and decisionmaking skills may limit their ability to assess risks accurately and make sound decisions 

about using drugs. Drug and alcohol abuse can disrupt brain function in areas critical to motivation, memory, learning, judgment, and

behavior control. So, it is not surprising that teens who abuse alcohol and other drugs often have family and school problems, poor 

academic performance, health-related problems (including mental health), and involvement with the juvenile justice system.

11

II. PREVENTING DRUG ABUSE: 

THE BEST STRATEGY
12

National drug use surveys indicate some children are 

already abusing drugs by age 12 or 13.

Drug abuse starts early and peaks in teen years

Infant Child Teen Adult Older Adult

First drug use (number of initiates)

Can science-validated 

programs prevent drug

addiction in youth?

Yes. The term “science-validated” means that

these programs have been rationally designed

based on current knowledge, rigorously 

tested, and shown to produce positive results.

Scientists have developed a broad range of 

programs that positively alter the balance

between risk and protective factors for drug

abuse in families, schools, and communities.

Research has shown that science-validated 

programs, such as those described in NIDA’s

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 illicit drugs. Other

programs reduce drug abuse among youngsters who have already begun abusing drugs

and alcohol. 
13

How do science-validated prevention programs work?

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 designed for individual or group settings, such as the school and home. There are

three types of programs—

❚ Universal programs address risk and protective factors common to all children in a given setting, such as a school 

or community. 

❚ Selective programs target groups of children and teens who have factors that further increase their risk of drug abuse. 

❚ Indicated programs are designed for youth who have already begun abusing drugs. 

Are all prevention programs effective in reducing drug abuse? 

When science-validated substance abuse prevention programs are properly implemented by schools and communities, alcohol,

tobacco, and illicit drug abuse are reduced. Such programs help teachers, parents, and healthcare professionals shape youths’

perceptions about the risks of drug abuse. While many events and cultural factors affect drug abuse trends, when youths perceive

drug abuse as harmful, they reduce their level of abuse.
60

50

40

30

20

10

0

Percent

Drug use decreases when drugs are perceived as harmful.

14

’77 ’79 ’81 ’83 ’85 ’87 ’89 ’91 ’93 ’95 ’97 ’99 ’01 ’03 ’05 ’07

■ Past Year Use

▲ Perceived Risk

Source: 2007 Monitoring the Future survey. University of Michigan, with funding from the National Institute on Drug Abuse.

PREVENTION IS THE BEST STRATEGY

Good news! 

Teen illicit drug

use declined 

by 24% from 

2001 to 2007.

Prevention plays 

a critical role in

the decline of

drug use.

22

20

18

16

14

12

10

2001 2002 2003 2004 2005 2006 2007

8th, 10th, and 12th Graders Combined

For more information on prevention, see NIDA’s most recent edition of Preventing Drug Use among Children and Adolescents: A ResearchBased Guide for Parents, Educators, and Community Leaders, at www.drugabuse.gov/Prevention/Prevopen.html.

Use of marijuana goes down when perceptions of harm go up.

Percent

19.4

18.2 17.3

16.2 15.8 14.9

12th Graders

STUDENTS REPORTING PAST MONTH USE

OF ANY ILLICIT DRUG

14.8
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. In brief, the brain regulates your basic body functions; enables you to interpret and respond to everything you experience;

and shapes your thoughts, emotions, and behavior. 

The brain is made up of many parts that all work together as a team. Different parts of the brain are responsible for coordinating and 

performing specific functions. Drugs can alter important brain areas that are necessary for life-sustaining functions and can drive the 

compulsive drug abuse that marks addiction. Brain areas affected by drug abuse—

❚ The brain stem controls basic functions critical to life, such as heart rate, breathing, and sleeping. 

❚ The limbic system contains the brain’s reward circuit—it links together a number 

of brain structures that control and regulate our ability to feel pleasure. Feeling 

pleasure motivates us to repeat behaviors such as eating—actions that are critical 

to our existence. The limbic system is activated when we perform these activities—

and also by drugs of abuse. In addition, the limbic system is responsible for our 

perception of other emotions, both positive and negative, which explains the 

mood-altering properties of many drugs.

❚ The cerebral cortex is divided into areas that control specific functions. 

Different areas process information from our senses, enabling us to see, feel, hear,

and taste. The front part of the cortex, the frontal cortex or forebrain, is the thinking

center of the brain; it powers our ability to think, plan, solve problems, and make 

decisions.

15

III. DRUGS AND THE BRAIN
How does the brain communicate? 

The brain is a communications center consisting of billions of 

neurons, or nerve cells. Networks of neurons pass messages back 

and forth to different structures within the brain, the spinal column,

and the peripheral nervous system. These nerve networks coordinate

and regulate everything we feel, think, and do. 

❚ Neuron to Neuron

Each nerve cell in the brain sends and receives messages in the

form of electrical impulses. Once a cell receives and processes a

message, it sends it on to other neurons. 

❚ Neurotransmitters—The Brain’s Chemical Messengers

The messages are carried between neurons by chemicals called

neurotransmitters. (They transmit messages between neurons.) 

❚ Receptors—The Brain’s Chemical Receivers

The neurotransmitter attaches to a specialized site on the receiving

cell called a receptor. A neurotransmitter and its receptor operate

like a “key and lock,” an exquisitely specific mechanism that

ensures that each receptor will forward the appropriate message

only after interacting with the right kind of neurotransmitter.

❚ Transporters—The Brain’s Chemical Recyclers

Located on the cell that releases the neurotransmitter, transporters

recycle these neurotransmitters (i.e., bring them back into the cell

that released them), thereby shutting off the signal between neurons.

16

Here’s how people communicate. Here’s how brain cells communicate.

To send a message a brain

cell releases a chemical

(neurotransmitter) into

the space separating two

cells called the synapse.

The neurotransmitter

crosses the synapse 

and attaches to proteins

(receptors) on the 

receiving brain cell. This

causes changes in the

receiving brain cell and

the message is delivered.

Transmitter Receptor Neurotransmitter Receptor

Concept courtesy: B.K. Madras
How do drugs work in the brain?

Drugs are chemicals. They work in the brain by tapping into the brain’s communication system and interfering with the way

nerve cells normally send, receive, and process information. Some drugs, such as marijuana and heroin, can activate neurons

because their chemical structure mimics that of a natural neurotransmitter. This similarity in structure “fools” receptors and

allows the drugs to lock onto and activate the nerve cells. Although these drugs mimic brain chemicals, they don’t activate nerve

cells in the same way as a natural neurotransmitter, and they lead to abnormal messages being transmitted through the network.

Other drugs, such as amphetamine or cocaine, can cause the nerve cells to release abnormally large amounts of natural 

neurotransmitters or prevent the normal recycling of these brain chemicals. This disruption produces a greatly amplified 

message, ultimately disrupting communication channels. The difference in effect can be described as the difference between

someone whispering into your ear and someone shouting into a microphone.

How do drugs work in the brain to produce pleasure?

All drugs of abuse directly or indirectly target the brain’s reward system by flooding the circuit with dopamine. Dopamine is 

a neurotransmitter present in regions of the brain that regulate movement, emotion, cognition, motivation, and feelings of 

pleasure. The overstimulation of this system, which rewards our natural behaviors, produces the euphoric effects sought by 

people who abuse drugs and teaches them to repeat the behavior.

17

All drugs of abuse target the brain’s reward system 

by flooding the circuit with dopamine. 
How does stimulation of the brain’s

pleasure circuit teach us to keep 

taking drugs?

Our brains are wired to ensure that we will repeat life-sustaining activities by associating those activities with pleasure or reward. Whenever

this reward circuit is activated, the brain notes that something important is happening that needs to be remembered, and teaches us to do 

it again and again, without thinking about it. Because drugs of abuse

stimulate the same circuit, we learn to abuse drugs in the same way.

Why are drugs more addictive than 

natural rewards?

When some drugs of abuse are taken, they can release 2 to 10 times

the amount of dopamine that natural rewards do. In some cases, this

occurs almost immediately (as when drugs are smoked or injected),

and the effects can last much longer than those produced by natural

rewards. The resulting effects on the brain’s pleasure circuit dwarfs

those produced by naturally rewarding behaviors such as eating and

sex. The effect of such a powerful reward strongly motivates people to

take drugs again and again. This is

why scientists sometimes say that

drug abuse is something we learn 

to do very, very well. 

18

ALL DRUGS OF ABUSE TARGET THE BRAIN’S PLEASURE CENTER

These brain circuits are important for natural

rewards such as food, music, and art.

Typically, dopamine increases in response to natural rewards such as food. 

When cocaine is taken, dopamine increases are exaggerated, and communication is altered.

FOOD COCAINE

Brain reward (dopamine) pathways All drugs of abuse increase dopamine

Frontal Cortex

Ventral

Tegmental

Area

Nucleus

Accumbens

Frontal Cortex

Ventral

Tegmental

Area

Nucleus

Accumbens

Dopamine

Transporter

Dopamine Dopamine

Receptor Cocaine Dopamine

Dopamine

Transporter
What happens to your brain 

if you keep taking drugs? 

Just as we turn down the volume on a radio that is too

loud, the brain adjusts to the overwhelming surges in

dopamine (and other neurotransmitters) by producing less

dopamine or by reducing the number of receptors that can

receive and transmit signals. As a result, dopamine’s impact

on the reward circuit of a drug abuser’s brain can become

abnormally low, and the ability to experience any pleasure

is reduced. This is why the abuser eventually feels flat, 

lifeless, and depressed, and is unable to enjoy things that

previously brought them pleasure. Now, they need to take

drugs just to bring their dopamine function back up to

normal. And, they must take larger amounts of the drug

than they first did to create the dopamine high—an effect

known as tolerance. 

How does long-term drug taking

affect brain circuits?

We know that the same sort of mechanisms involved 

in the development of tolerance can eventually lead to 

profound changes in neurons and brain circuits, with the

potential to severely compromise the long-term health of

the brain. For example, glutamate is another neurotransmitter that influences the reward circuit and the ability to

learn. When the optimal concentration of glutamate is

altered by drug abuse, the brain attempts to compensate

for this change, which can cause impairment in cognitive

function. Similarly, long-term drug abuse can trigger 

Long-term drug abuse impairs brain functioning.

19

Healthy Control Drug Abuser

Methamphetamine abusers have significant reductions in dopamine transporters.

Source: Am J Psychiatry 158:377–382. 2001.

DECREASED BRAIN FUNCTION IN

METHAMPHETAMINE ABUSER
adaptations in habit or nonconscious memory systems. Conditioning 

is one example of this type of learning, whereby environmental 

cues become associated with the drug experience and can trigger

uncontrollable cravings if the individual is later exposed to these cues,

even without the drug itself being available. This learned “reflex” is

extremely robust and can emerge even after many years of abstinence.

What other brain changes 

occur with abuse? 

Chronic exposure to drugs of abuse disrupts the way critical brain

structures interact to control behavior—behavior specifically related

to drug abuse. Just as continued abuse may lead to tolerance or the

need for higher drug dosages to produce an effect, it may also lead 

to addiction, which can drive an abuser to seek out and take drugs

compulsively. Drug addiction erodes a person’s self-control and 

ability to make sound decisions, while sending intense impulses to

take drugs.

20

For more information on drugs and the brain, order NIDA’s Slide Teaching Packets CD-ROM series or the Mind Over Matter series at 

www.drugabuse.gov/parent-teacher.html. These items and others are available to the public free of charge.
What are the medical consequences of drug addiction?

I

ndividuals who suffer from addiction often have one or more accompanying medical issues, including lung and cardiovascular disease,

stroke, cancer, and mental disorders. Imaging scans, chest x-rays, and blood tests show the damaging effects of drug abuse throughout

the body. For example, tests show that tobacco smoke causes cancer of the mouth, throat, larynx, blood, lungs, stomach, pancreas, 

kidney, bladder, and cervix. In addition, some drugs of abuse, such as inhalants, are toxic to nerve cells and may damage or destroy them

either in the brain or the peripheral nervous system. 

Does drug abuse cause mental disorders, 

or vice versa?

Drug abuse and mental disorders often co-exist. In some cases, mental diseases may precede

addiction; in other cases, drug abuse may trigger or exacerbate mental disorders, particularly

in individuals with specific vulnerabilities. 

21

IV. ADDICTION AND HEALTH

THE IMPACT OF 

ADDICTION CAN BE 

FAR REACHING

❚ Cardiovascular disease

❚ Stroke

❚ Cancer

❚ HIV/AIDS

❚ Hepatitis B and C

❚ Lung disease

❚ Obesity

❚ Mental disorders
What harmful consequences 

to others result from drug addiction?

Beyond the harmful consequences for the addicted individual, drug

abuse can cause serious health problems for others. Three of the

more devastating and troubling consequences of addiction are: 

❚ Negative effects of prenatal drug exposure on infants

and children. 

It is likely that some drug-exposed children will need educational

support in the classroom to help them overcome what may be 

subtle deficits in developmental areas such as behavior, attention,

and cognition. Ongoing work is investigating whether the effects of

prenatal exposure on brain and behavior extend into adolescence

to cause developmental problems during that time period.

❚ Negative effects of second-hand smoke. 

Second-hand tobacco smoke, also referred to as environmental

tobacco smoke (ETS), is a significant source of exposure to a large 

number of substances known to be hazardous to human health,

particularly to children. According to the Surgeon General’s 2006

Report, The Health Consequences of Involuntary Exposure to

Tobacco Smoke, involuntary smoking increases the risk of heart

disease and lung cancer in never-smokers by 25–30 percent and

20–30 percent, respectively.

22

❚ Increased spread of infectious diseases. 

Injection of drugs such as heroin, cocaine, and methamphetamine

accounts for more than a third of new AIDS cases. Injection drug

use is also a major factor in the spread of hepatitis C, a serious,

potentially fatal liver disease and a rapidly growing public health

problem. Injection drug use is not the only way that drug abuse

contributes to the spread of infectious diseases. All drugs of abuse

cause some form of intoxication, which interferes with judgment

and increases the likelihood of risky sexual behaviors. This, in turn,

contributes to the spread of HIV/AIDS, hepatitis B and C, and other

sexually transmitted diseases. 

4 OUT OF 10 U.S. AIDS DEATHS ARE 

RELATED TO DRUG ABUSE

Drug abuse and HIV/AIDS are intertwined epidemics.
What are some effects 

of specific abused substances?

❚ Nicotine is an addictive stimulant found in cigarettes 

and other forms of tobacco. Tobacco smoke increases 

a user’s risk of cancer, emphysema, bronchial disorders,

and cardiovascular disease. The mortality rate associated

with tobacco addiction is staggering. Tobacco use killed

approximately 100 million people during the 20th century

and, if current smoking trends continue, the cumulative

death toll for this century has been projected to reach 

1 billion.

❚ Alcohol consumption can damage the brain and most

body organs. Areas of the brain that are especially 

vulnerable to alcohol-related damage are the cerebral 

cortex (largely responsible for our higher brain functions,

including problemsolving and decisionmaking), the 

hippocampus (important for memory and learning), and

the cerebellum (important for movement coordination).

❚ Marijuana is the most commonly abused illicit substance.

This drug impairs short-term memory and learning, the

ability to focus attention, and coordination. It also increases

heart rate, can harm the lungs, and can cause psychosis in

those at risk.

❚ Inhalants are volatile substances found in many household products, such as oven cleaners, gasoline, spray

paints, and other aerosols, that induce mind-altering

effects. Inhalants are extremely toxic and can damage the

heart, kidneys, lungs, and brain. Even a healthy person can

suffer heart failure and death within minutes of a single

session of prolonged sniffing of an inhalant.

❚ Cocaine is a short-acting stimulant, which can lead

abusers to “binge” (to take the drug many times in a 

single session). Cocaine abuse can lead to severe medical

consequences related to the heart, and the respiratory,

nervous, and digestive systems.

Tobacco use is responsible for an estimated 

5 million deaths worldwide each year. 23

TOBACCO SMOKE AFFECTS THE WHOLE BODY

Smoking causes cancer throughout the body.

Source: PNAS;100:11600-11605. 2003. Source: The Health Consequences of Smoking: A Report of

the Surgeon General. 2004.

Throat

Larynx (voice box)

Esophagus

Lung

Kidney

Bladder

Mouth

Blood (leukemia)

Stomach

Pancreas

Cervix

Monoamine Oxidase B
❚ Amphetamines, including methamphetamine, are powerful 

stimulants that can produce feelings of euphoria and alertness.

Methamphetamine’s effects are particularly long lasting and harmful

to the brain. Amphetamines can cause high body temperature and

can lead to serious heart problems and seizures. 

❚ Ecstasy (MDMA) produces both stimulant and mind-altering

effects. It can increase body temperature, heart rate, blood 

pressure, and heart wall stress. Ecstasy may also be toxic to 

nerve cells. 

❚ LSD is one of the most potent hallucinogenic, or perceptionaltering, drugs. Its effects are unpredictable, and abusers may see

vivid colors and images, hear sounds, and feel sensations that seem

real but do not exist. Abusers also may have traumatic experiences

and emotions that can last for many hours. Some short-term 

effects can include increased body temperature, heart rate, and

blood pressure; sweating; loss of appetite; sleeplessness; dry mouth;

and tremors. 

❚ Heroin is a powerful opiate drug that produces euphoria and 

feelings of relaxation. It slows respiration and can increase risk of

serious infectious diseases, especially when taken intravenously.

Other opioid drugs include morphine, OxyContin, Vicodin, and

Percodan, which have legitimate medical uses; however, their nonmedical use or abuse can result in the same harmful consequences

as abusing heroin. 

❚ Prescription medications are increasingly being abused 

or used for nonmedical purposes. This practice cannot only be

addictive, but in some cases also lethal. Commonly abused classes

of prescription drugs include painkillers, sedatives, and stimulants.

Among the most disturbing aspects of this emerging trend is its

prevalence among teenagers and young adults, and the common

misperception that because these medications are prescribed by

physicians, they are safe even when used illicitly.

❚ Steroids, which can also be prescribed for

certain medical conditions, are abused to

increase muscle mass and to improve athletic

performance or physical appearance. Serious

consequences of abuse can include severe

acne, heart disease, liver problems, stroke,

infectious diseases, depression, and suicide. 

❚ Drug combinations. A particularly dangerous and not uncommon practice is the combining of two or more drugs. The practice

ranges from the co-administration of legal drugs, like alcohol and

nicotine, to the dangerous random mixing of prescription drugs, to

the deadly combination of heroin or cocaine with fentanyl (an opioid pain medication). Whatever the context, it is critical to realize

that because of drug–drug interactions, such practices often pose

significantly higher risks than the already harmful individual drugs.

Nearly 1 in 10 high school seniors report nonmedical use 

24 of the prescription pain reliever Vicodin.

For more information on the nature and extent of common drugs of abuse and their health consequences, go to NIDA’s Web site

(www.drugabuse.gov) to order free copies of the popular Research Reports (www.drugabuse.gov/ResearchReports/ResearchIndex.html), InfoFacts,

and other publications.
Can addiction be treated successfully?

YES.

Addiction is a treatable disease. Discoveries in the science of addiction have led to advances in drug abuse treatment that help

people stop abusing drugs and resume their productive lives. 

Can addiction be cured?

Addiction need not be a life sentence. Like other chronic diseases, addiction can be managed successfully. Treatment enables people to

counteract addiction’s powerful disruptive effects on brain and behavior and regain control of their lives. 

25

V. TREATMENT AND RECOVERY 

Healthy Person

Source: J Neurosci 21:9414–9418. 2001.

METH Abuser

1 month abstinence

METH Abuser

14 months abstinence

RECOVERY OF BRAIN FUNCTION WITH PROLONGED ABSTINENCE

These images of the dopamine

transporter show the brain’s

remarkable potential to recover,

at least partially, after a long

abstinence from drugs—in this

case, methamphetamine.
Does relapse to drug abuse mean 

treatment has failed?

No. 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.

What are the basics of effective 

addiction treatment?

Research shows that combining treatment medications, where 

available, with behavioral therapy is the best way to ensure success 

for most patients. Treatment approaches must be tailored to address

each patient’s drug abuse patterns and drug-related medical, 

psychiatric, and social problems. 

How can medications 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. 

❚ Treating Withdrawal. When patients first stop abusing drugs,

they can experience a variety of physical and emotional symptoms,

including depression, anxiety, and other mood disorders; restlessness;

Addiction need not be a life sentence.

26

Relapse rates for drug-addicted patients are compared with those suffering from diabetes, 

hypertension, and asthma. Relapse is common and similar across these illnesses (as is adherence 

to medication). Thus, drug addiction should be treated like any other chronic illness, with relapse

serving as a trigger for renewed intervention.

Source: McLellan et al., JAMA 284:1689–1695. 2000.

COMPARISON OF RELAPSE RATES BETWEEN 

DRUG ADDICTION AND OTHER CHRONIC ILLNESSES

100

80

60

40

20

0

Drug

Addiction

Percent of Patients Who Relapse

40 to 60%

30 to 50%

50 to 70% 50 to 70%

Type I

Diabetes

Hypertension Asthma
and sleeplessness. Certain treatment 

medications are designed to reduce these

symptoms, which makes it easier to stop

the abuse.

❚ Staying in Treatment. Some treatment

medications are used to help the brain

adapt gradually to the absence of the

abused drug. These medications act slowly

to stave off drug cravings, and have a 

calming effect on body systems. They can

help patients focus on counseling and 

other psychotherapies related to their drug

treatment.

❚ Preventing Relapse. Science has 

taught us that stress, cues linked to the

drug experience (e.g., people, places,

things, moods), and exposure to drugs 

are the most common triggers for relapse.

Medications are being developed to 

interfere with these triggers to help patients

sustain recovery.

How do behavioral therapies

treat drug addiction?

Behavioral treatments help engage people in

drug abuse treatment, modifying their attitudes

and behaviors related to drug abuse and

increasing their life skills to handle stressful

circumstances and environmental cues that

may trigger intense craving for drugs and

prompt another cycle of compulsive abuse.

Moreover, behavioral therapies can enhance

the effectiveness of medications and help 

people remain in treatment longer.

27

■ Tobacco Addiction

• Nicotine replacement 

therapies (e.g., patch, 

inhaler, gum)

• Bupropion

• Varenicline

■ Opioid Addiction

• Methadone

• Buprenorphine

■ Alcohol and Drug Addiction

• Naltrexone—helps prevent

relapse to alcohol and heroin

abuse

• Disulfiram—helps prevent

relapse to alcohol abuse; currently

being tested for treating cocaine

abuse

• Acamprosate—helps prevent

relapse to alcohol abuse Discoveries in science lead to advances in drug abuse treatment.

MEDICATIONS USED TO 

TREAT DRUG ADDICTION
How do the best treatment programs

help patients recover from the pervasive

effects of addiction?

Getting an addicted person to stop abusing drugs is just one part of a

long and complex recovery process. When people enter treatment, 

addiction has often taken over their lives. The compulsion to get drugs,

take drugs, and experience the effects of drugs has dominated their

every waking moment, and drug abuse has taken the place of all the

things they used to enjoy doing. It has disrupted how they function in

their family lives, at work, and in the community, and has made them

more likely to suffer from other serious illnesses. Because addiction

can affect so many aspects of a person’s life, treatment must address

the needs of the whole person to be successful. This is why the best

programs incorporate a variety of rehabilitative services into their 

comprehensive treatment regimens. Treatment counselors select from

a menu of services for meeting the individual medical, psychological,

social, vocational, and legal needs of their patients to foster their

recovery from addiction.

For more information on drug treatment, NIDA offers a 

selection of free treatment manuals and guides for practitioners,

including Principles of Drug Addiction Treatment: A ResearchBased Guide (www.drugabuse.gov/PODAT/PODATIndex.html) 

and Brief Strategic Family Therapy for Adolescent Drug Abuse

(www.drugabuse.gov/TXManuals/bsft/bsftindex.html).

Treatment must address the whole person.

28

❚ Cognitive Behavioral Therapy. Seeks to help patients recognize, avoid,

and cope with the situations in which they are most likely to abuse drugs.

❚ Motivational Incentives. Uses positive reinforcement such as providing

rewards or privileges for remaining drug free, for attending and participating

in counseling sessions, or for taking treatment medications as prescribed. 

❚ Motivational Interviewing. Employs strategies to evoke rapid and 

internally motivated behavior change to stop drug use and facilitate 

treatment entry.

❚ Group Therapy. Helps patients face their drug abuse realistically, come to

terms with its harmful consequences, and boost their motivation to stay drug

free. Patients learn effective ways to solve their emotional and interpersonal

problems without resorting to drugs.
Leading the Search for Scientific Solutions

To address all aspects of drug abuse and its harmful consequences, NIDA’s research 

program ranges from basic studies of the addicted brain and behavior to health services

research. NIDA’s research program develops prevention and treatment approaches 

and ensures they work in real-world settings. In this context, NIDA is strongly committed to

developing a research portfolio that addresses the special vulnerabilities and health disparities

that exist among ethnic minorities or that derive from gender differences.

Bringing Science to Real-World Settings

❚ National Drug Abuse Treatment Clinical Trials Network (CTN).

The CTN “road tests” research-based drug abuse treatments in community treatment 

programs around the country. 

❚ Criminal Justice Drug Abuse Treatment Studies (CJ-DATS). Led by NIDA, CJ-DATS 

is a network of research centers, in partnership with criminal justice professionals, drug

abuse treatment providers, and Federal agencies responsible for developing integrated 

treatment approaches for criminal justice offenders and testing them at multiple sites 

throughout the Nation. 

Sharing Free Information With the Public

NIDA further increases the impact of its research on the problems of addiction by sharing free information about its findings with professional

audiences and the general public. Special initiatives target students and teachers, designated populations, and ethnic groups.

29

VI. ADVANCING ADDICTION SCIENCE 

AND PRACTICAL SOLUTIONS 

NIDA Studies

DRUG ABUSE & ADDICTION 

at All Levels
Publications on Prevention

and Treatment Principles

Preventing Drug Use among Children 

and Adolescents: A Research-Based Guide—

NIDA’s research-based guide for preventing drug

abuse among children and adolescents provides 

16 principles derived from effective drug abuse 

prevention research, and includes answers to 

questions on risk and protective factors, as well as

community planning and implementation, to help

prevention practitioners use research results to

address drug abuse among children and adolescents

in communities across the country.

Principles of Drug Addiction Treatment: 

A Research-Based Guide—

This guide summarizes the 13 principles of effective

treatment, answers common questions, and

describes types of treatment, providing examples of

scientifically based and tested treatment components. 

Principles of Drug Abuse Treatment for

Criminal Justice Populations: A ResearchBased Guide—NIDA’s research-based guide for

treating drug abusers involved with the criminal 

justice system provides 13 essential treatment 

principles, and includes answers to frequently 

asked questions and resource information.

30

For more information:

NIDA’s publications are available free of

charge and are downloadable from the 

NIDA Web site (www.drugabuse.gov). 

The NIDA site also contains additional

research-based information about drugs, 

drug abuse, and addiction. You can also 

order NIDA’s materials by calling the 

National Clearinghouse for Alcohol and 

Drug Information at 800-729-6686.

NIDA’s Special Initiatives

for Students, Teachers,

and Parents

NIDA Goes Back to

School—Targets grade

school, middle school, 

and high school students and teachers. 

www.backtoschool.drugabuse.gov 

Heads Up: Real 

News About Drugs 

and Your Body—

A drug education series created 

by NIDA and SCHOLASTIC INC. for 

students in grades 6 to 12. 

www.teacher.scholastic.com/

scholasticnews/indepth/headsup

NIDA for Teens: The

Science Behind Drug

Abuse—An interactive 

Web site geared specifically for adolescents that contains age-appropriate facts

on drugs, real stories about teens and

drug abuse, games, take-home activities,

and a Q&A forum with Dr. NIDA.

www.teens.drugabuse.gov
www.drugabuse.gov
National Institutes of Health

NIH Pub No. 07-5605

Printed April 2007

Reprinted February 2008