Addiction is a chronic, often relapsing brain disease that causes compulsive drug seeking and use, despite harmful consequences to the addicted individual and to those around him or her.  Although the initial decision to take drugs is voluntary for most people, the brain changes that occur over time challenge an addicted person's self-control and hamper his or her ability to resist intense impulses to take drugs.

Similar to other chronic, relapsing diseases, such as diabetes, asthma, or heart disease, drug addiction can be managed successfully.  As with other chronic diseases, it is not uncommon for a person to relapse and begin abusing drugs again.  Relapse, however, does not signal treatment failure-rather, it indicates that treatment should be reinstated or adjusted or that an alternative treatment is needed to help the individual regain control and recover.

What Happens to Your Brain When You Take Drugs?

Drugs are chemicals that tap into the brain's communication system and disrupt the way nerve cells normally send, receive, and process information.  There are at least two ways that drugs cause this disruption: by imitating the brain's natural chemical messengers and/or by over stimulating the "reward circuit" of the brain.

Some drugs, such as marijuana and heroin, have a similar structure to chemical messengers called neurotransmitters, which are naturally produced by the brain.  This similarity allows the drugs to "fool" the brain's receptors and activate nerve cells to send abnormal messages.  Other drugs, such as cocaine or methamphetamine, can cause the nerve cells to release abnormally large amounts of natural neurotransmitters or to prevent the normal recycling of these brain chemicals, which is needed to shut off the signal between neurons.  This disruption produces a greatly amplified message that ultimately disrupts normal communication patterns.

Nearly all drugs, 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 control movement, emotion, motivation, and feelings of pleasure.  The over stimulation of this system, which normally responds to natural behaviors that are linked to survival (eating, spending time with loved ones, etc), produces euphoric effects in response to the drugs.  This reaction sets in motion a pattern that "teaches" people to repeat the behavior of abusing drugs.

A a person continues to abuse drugs, the brain adapts to the dopamine surges by producing less dopamine or reducing the number of dopamine receptors.  The user must therefore keep abusing drugs to bring his or her dopamine function back to "normal" or use more drugs to achieve a dopamine high.

Long-term drug abuse causes changes in other brain chemical systems and circuits, as well.  Brain imaging studies of drug-addicted individuals show changes in areas of the brain that are critical to judgment, decision-making, learning and memory, and behavior control.  Together, these changes can drive an abuser to seek out and take drugs compulsively--in other words, to become addicted to drugs.

Why Do Some People Become Addicted While Others Do Not?

No single factor can predict whether a person will become addicted to drugs.  Risk for addiction is influenced by a combination of factors that include individual biology, social environment, and age or stage of development.  The more risk factors an individual has, the greater the chance that taking drugs can lead to addiction.  For example:


  • Biology.  The genes that people are born with-in combination with environmental influences-account for about half of their addiction vulnerability.  Additional, gender, ethnicity, and the presence of other mental disorders may influence risk for drug abuse and addiction.
  • Environment.  A person's environment includes many different influences, from family and friends to socioeconomic status and quality of life in general.  Factors such as peer pressure, physical and sexual abuse, stress, and quality of parenting can greatly influence the occurrence of drug abuse and the escalation to addiction in a person's life.
  • Development. Genetic and environmental factors interact with critical developmental stages in person's life to affect addiction vulnerability.  Although taking drugs at any age can lead to addiction, the earlier that drug use begins, the more likely it will progress to move serious abuse, which poses a special challenge to adolescents.  Because areas in their brains that govern decision making, judgment, and self-control are still developing, adolescents may be especially prone to risk-taking behaviors, including trying drugs of abuse.

Painkiller, Narcotic Abuse, and Addiction

One of the most frequent reasons people go to the doctor is for pain relief.  There are a number of different drugs that can ease pain.  Opioids--also called opiates or narcotics--pain relievers made from opium, which comes from the poppy plant.  Morphine and codeine are the two natural products of opium.  Synthetic modifications or imitations or morphine produce the other opioids:

  • Heroin
  • Dilaudid
  • Percocet, Percodan, OxyContin
  • Vicodin, Lorcet, Lortab
  • Demerol
  • Methadone
  • Duragesic

When people use narcotics only to control pain, they are unlikely to become addicted to the drugs.  However, opioids provide an intoxication high when injected or taken orally in high doses.  Opioids are also powerful anxiety relievers.  For these reasons, narcotic abuse is one of the most common forms of drug abuse in the U.S.

Prevention Is the Key

Drug addiction is a preventable disease. Research has shown that prevention programs involving families, schools, communities, and the media are effective in reducing drug abuse.  Although many events and cultural factors affect drug abuse trends, when youths perceive drug abuse as harmful, they reduce their drug taking.  Thus, education and outreach are key in helping youth an the general public understand the risks of drugs and drug dependence.

This article posted on the National Council on Alcoholism and Drug Dependence webiste.