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What Is Drug Addiction?

Alcohol and other Drug (AOD) Addiction is a chronic brain disease, often characterized by relapse, which causes compulsive AOD seeking and use/abuse, despite harmful consequences to the addicted individual and to those around him or her. Although the initial decision to take drugs is voluntary for many 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, regardless of the initial reason the person started drinking or using.

Fortunately, treatments are available to help people counter powerful disruptive effects often present in AOD addiction. Research shows that combining addiction treatment medications with Cognitive/behavioral therapy (CBT) is a positive method to ensure success for most patients. Treatment approaches that are tailored to each patient’s drug abuse patterns (and drug preferences, since some are stronger and some are weaker) and any co-occurring medical, psychiatric, and social problems can lead to sustained recovery and a meaning, purposeful life, without AOD.

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 using/abusing AOD again. Relapse DOES NOT; however, signal treatment failure—rather, relapse many times indicates that a treatment plan should be reassessed and that an alternative treatment intervention/level of care change is needed to help the addict sustain recovery.

What Happens to Your Brain When You Take Drugs?

Drugs contain chemicals that tap into the brain’s communication system and disrupt the way nerve cells normally send, receive, and process information. A couple of ways that drugs cause this disruption: (1) by imitating the brain’s natural chemical messengers and (2) by overstimulation of the “reward circuit” of the brain, by releasing huge surges of dopamine in the midbrain.

Some drugs (e.g., 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 (mainly dopamine) or to prevent the normal recycling of these brain chemicals, which is needed to shut off the signaling between neurons. The result is a brain awash in dopamine, a neurotransmitter present in brain regions that control movement, emotion, motivation, and feelings of pleasure. The overstimulation of this reward system, which normally responds to natural behaviors linked to survival (eating, spending time with loved ones, recreation, rest, etc.), produces euphoric effects in response to AOD. This reaction sets in motion a reinforcing pattern that “teaches” people to repeat the rewarding behavior of abusing drugs. The AOD of abuse acquire “survival salience”, in other words, the addict’s brain believes that the AOD he or she is abusing is vital to actual survival.

As a person continues to abuse AOD, the brain adapts to the overwhelming surges in dopamine by producing less dopamine or by reducing the number of dopamine receptors in the reward circuit. The result is a lessening of dopamine’s impact on the reward circuit, which reduces the abuser’s ability to enjoy not only the AOD but renders them unable to derive normal pleasure from normally pleasurable things. The decreased sensation of pleasure motivates the addicted person to keep abusing AOD in an attempt to once again create a pleasurable experience, but now larger amounts of the AOD are required to achieve the same dopamine high—an effect known as tolerance.

Long-term abuse causes changes in other brain chemical systems and circuits as well. Glutamate is a neurotransmitter that influences the reward circuit and the ability to learn. When the optimal concentration of glutamate is altered by AOD abuse, the brain attempts to compensate, which can impair cognitive function. 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 (CHOICES!). Together, these changes can drive an abuser to seek out and take drugs compulsively despite adverse, even devastating consequences—that is the nature of addiction.

Persistent AOD Use Despite Negative Consequences

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:


The genes that people are born with—in combination with environmental influences—account for about half of their addiction vulnerability. A hyper-sensitive/hyper-reactive stress system, caused by early onset trauma (even in the womb, if mother is exposed to high levels of stress, such as physical/domestic abuse, sexual abuse etc while pregnant) can be a dominant precursor to addiction, as well. The Stress system interrelates with the Reward system and creates neurochemical malfunctions which lead to an inability to properly perceive pleasure. The Memory system then gets into the act and “locks-in” drinking and using responses(triggers, cues) and tags them as a beneficial and life-sustaining (although this is errant) response to stress.

Additionally, gender, ethnicity, and the presence of other mental disorders may influence risk for AOD abuse and addiction.


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 AOD abuse and the escalation to addiction in a person’s life.


Genetic and environmental factors interact with critical developmental stages in a 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 AOD use will progress to more serious AOD 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.

Prevention Is Possible

Drug addiction can be a preventable disease, at least in terms of life-long abstinence. Results from NIDA-funded research have 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 young, impressionable persons perceive drug abuse as harmful, they may be able to reduce or eliminate their drug taking, depending upon the strength and addiction-potential of the AOD they are using. Thus, education and outreach are key in helping youth and the general public understand the risks of drug abuse, especially as it relates to potential addiction. Teachers, parents, medical, and public health professionals must keep sending the message that drug addiction can be prevented if a person, especially someone with a genetic vulnerability to AOD addiction never begins to drink and/or use AOD drugs.

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