How Addiction Works

Our understanding of addiction, including dependency on substances like heroin (shown above), has increased tremendously over the past three decades. See more drug pictures.
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Stories about how addiction has ruined lives are common in our society today. Reports of the lengths addicts will go to and the dark acts they will commit to get drugs, like crack cocaine, heroin and even alcohol, abound -- serving as cautionary tales to keep others from following the same path.

­­There are many questions about the nature of addiction. Is denial a good indicator of addiction? Are some drugs as addictive as people say? There are even questions when it comes to drug- and alcohol-use prevention tactics. In order to persuade a person not to use a substance, the pitfalls of addiction are sometimes overstated. Overexaggeration can cause feelings of distrust.


Perhaps the best approach to the prevention of substance abuse is a clear, concise understanding of the process of addiction and the effects it can have on the user. To that end, researchers have arrived at a trim and science-based view of addiction. We have learned much in the last few decades, including the idea that addiction can come not only from abusing substances, but also with behaviors like sex and eating.


Though we've come far in the study of addiction, it's still a relatively new concept. Just a few hundred years ago, and for centuries before that, the general attitude toward alcohol was that it was consumed because people wanted to consume it, not because of any internal or external necessity [source: Levine]. But as reports and confessions came in from people who felt an irresistible urge to consume alcohol and drugs (once they became more accessible), our idea about some substances changed, and we developed the concept of addiction.

It was originally believed that some substances, like alcohol and, later, opium, possessed addictive properties, meaning their contents were to blame. That idea later shifted, and addiction was believed to be part of the addict's character. Dependence on drugs and alcohol was seen as a personality flaw -- that the person couldn't behave himself. Later, addiction came to be seen as something from which a person suffered, like a disease.

Although we know that certain substances act on the brain in ways that make the individual want to use more, drug addicts and alcoholics are still widely considered by society to be depraved; after all, they chose to use drugs in the first place. And with all of the data available and medical advances achieved in identifying the different aspects of alcohol and substance abuse, science is still struggling with some key questions, like whether it's ultimately substances that are addictive or people who are addicted to substances -- or both.

In this article, we'll examine the current ideas about addiction and look at the ways science is continuing its research to understand, once and for all, the mystery of addiction.



Addiction as a 'Brain Disease'

Marijuana acts as neurotransmitter, attaching to dopamine receptors and causing the release of dopamine in the brain.

We become addicted to a substance or activity for the same reason that we initially try it: Because we like the way it makes us feel. And although some people may try a drug, take a drink or eat a donut and never become hooked, almost all of us have the capability to become addicted. Users cross a threshold and undergo a transition to addiction.

Research has shone light on the changes that take place in the brain after this transition, developing the "brain disease" model of addiction. It's currently the most widely held view of addiction among the scientific community.


The way we learn to survive is based on a reward system. When we do something that aids in our survival, like eating or exercising, our brain's limbic system rewards us for this behavior by releasing dopamine, a chemical that makes us feel good. Since we like the way we feel, we learn to repeat the behavior.

Different substances approach the limbic system -- the reward center -- in our brains in different ways, but all substances of abuse cause the brain to release high levels of dopamine. This release can be two to 10 times the amount our brain releases normally, giving the user a sense of a "rush" or "high."

Because of this release and its impact on the brain's reward center, users learn very quickly to use a substance or engage in an activity. They learn this in the same way they learn to eat or exercise, but even faster and with more intensity, since the release of dopamine is so much larger. Since the amount of dopamine released is abnormal, the brain struggles to regain its normal chemical balance after a substance wears off. This produces a hangover, or withdrawal, from a substance, which can manifest in physical pain, depression and even dangerous behavior.

Over time, prolonged use of a substance can lead the brain to stop producing as much dopamine as it naturally does. This creates further withdrawal, leading to a physical dependency -- the addict needs to use more of the substance just to feel normal, creating a vicious cycle that can be difficult to break.

Because of this learning process and eventual physical dependence on a substance, the substance user becomes a substance abuser. As a result, the abuser loses control over the act of taking a substance or engaging in an activity. This has led to the idea that in order to cure an addiction, abstinence -- total discontinuation of substance use or behavior -- is necessary.

Under the disease model of addiction, the brain's motivational center becomes reorganized. The priorities are shuffled so that finding and using the substance (or another substance that will produce similar effects) becomes top priority as far as the brain is concerned. In this sense, the drug has essentially taken over the brain, and the addict is no longer in control of his behavior. An alcoholic won't, for example, have trouble deciding whether or not to get in his car and drive to the store to get more alcohol -- the urge will be irresistible.

But simply going to the store to buy alcohol is not a definitive sign of alcoholism. So how can you tell the difference between using a substance and being addicted to it? In the next section, we'll learn about the symptoms of addiction.


Addiction Symptoms

One symptom of addiction is using more of a substance or using
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Through extensive study of addicts and what makes them tick, science has narrowed down behaviors and traits that are symptoms of addiction. These symptoms are divided into two types: physical and behavioral.

Compulsive behavior, like a sex or gambling addiction, relate only to behavioral symptoms. But substance abuse can include both types:


  • Physical: In an addicted person, tolerance for a substance will increase (meaning he will need more of a substance to get the "high" he seeks), or it will decrease (meaning it will take less of the substance to obtain the high). The addict will also display withdrawal symptoms when he discontinues use of the substance. These symptoms include sweating, hand tremors, trouble sleeping, nausea, physical agitation, anxiety, hallucinations and seizures. Or, the addict will use more of the substance (or another substance) to reduce or eliminate these symptoms.
  • Behavioral: The addicted person will most likely have a history of attempting to stop using the substance (or engaging in the behavior) without much success. He will also use more of the substance or spend more time using the substance than he intends to, and will also spend a lot of his time getting, using and recovering from the substance. Another symptom is discontinuing other activities that once brought him pleasure (like walking in the park), or are his personal responsibility (like going to school or work). Lastly, the addicted person will continue taking the substance or engaging in the activity even though he knows that it's having a harmful impact on him.

Taken together, these symptoms constitute addiction. In conjunction with the "brain disease" model, these symptoms of addiction have created the view that addiction is a chronic disease, just like asthma. Based on this, researchers have determined that addicted people, like asthma sufferers, may experience relapses and that rehab programs for addiction should include "booster sessions."

While these are the symptoms of addiction, it has been shown that some people are more susceptible than others to falling prey to it. It has been long-held that initial drug use is a voluntary act, but behavioral psychologists point out that isn't necessarily the case. There are a variety of risk factors that have been identified which can lead a person into addiction. Variables like genetics (more on that coming up), peer pressure, existing psychological disorders, anxiety and depression and the quality of a person's home life can all lead him to becoming addicted to a substance or behavior.

A person who is depressed, for example, may try drugs in an attempt to self-medicate, or he may engage in sexual behavior to try to improve his sense of self-worth. Both of these behaviors can lead to an addiction to the substance or behavior. In the next section, we'll look at a few of the substances and behaviors people can become addicted to.­ ­­


Substance Abuse

Used needles litter the ground outside an abandoned building where many addicts live in Kabul, Afghanistan.
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Different substances produce different levels of highs, hangovers, addictions and cravings. Some will produce few physical withdrawals but strong cravings. Others can do just the opposite. Some addiction researchers have concluded that psychological dependence is the more extreme of the two, as it has more widespread consequences for both the person (by destroying personal relationships) and society at large (through crime committed to get drugs).

There are a wide variety of substances that a person can become addicted to. In 21st-century America, some of the worst and most often used drugs are:


  • Methamphetamines - prolonged use of this stimulant can lead to psychotic-like symptoms such as strong hallucinations and violent behavior. Studies of the brain patterns of some long-term meth users have shown that up to 50 percent of their dopamine-producing cells have been damaged. Use of meth has declined from 2001 to today [source: DEA].
  • Prescription medications - this is one of the rapidly growing substances of abuse in the United States. Between 1980 and 1998, abuse of prescription drugs increased 400 percent. It has about the same amount of usage in America as cocaine [source: NIDA].
  • Heroin - In 2005, 2.4 percent of the American population said they had tried heroin at least once [source: Department of Health]. Heroin withdrawal symptoms are particularly painful and can come on just a few hours after a dose wears off. Because of this, users have a high chance for relapse; in 2004, the entrance rate for heroin treatment for the fifth time or more was higher than the entrance rate for first-time heroin treatment [source: NIDA].
  • Alcohol - physicians consider alcohol more dangerous to suddenly withdraw from than even heroin, due to the physical symptoms that come along with alcohol withdrawal. In 2003, there was an estimated 18 million alcoholics in the United States [source: NIAAA]. Alcoholics are also prone to relapse; in 2004, 22 percent of alcoholics in the United States who sought treatment had been in rehab for alcohol at least one other time [source: NIDA].

It's not just substances that a person can become addicted to. Behaviors like eating and sex can become compulsive in some people. Although someone addicted to a behavior experiences the same flux of dopamine, when the compulsive behavior is stopped, he will not experience physical symptoms like a substance abuser. Still, the effects compulsive addictions can have on a person's life can be just as devastating. Some of the most common compulsive behaviors are:

  • Sex addiction - characterized by an overly intense sex drive or an obsession with sex. A sex addict will engage in risky sexual behavior, even at the cost of his relationships or health. He may have a number of affairs, but will have trouble forming bonds or even enjoying the act. When treating sexual addiction, the goal is not abstinence, but a return to non-harmful sexual behavior.
  • Food - food addiction is called binge-eating disorder. It's much like bulimia, but rather than binging on and purging food compulsively, the food addict only binges. An estimated 2 percent of people in the United States had a binge eating disorder in 2005 [source: Anred].
  • Gambling - there were an estimated 2-million-plus gambling addicts in the United States in 2002. Just as with a drug, a gambling addict gets a rush from the act of betting. He will also lose control of his ability to not bet. Unlike treatment for sex or food addictions, abstinence is considered the goal of rehab for gambling addiction [source: Biotie].

In the next section, we'll learn what science is doing to fight addiction.


Addiction Treatments

Geneticists are isolating genes, hormones and chemicals in the brain that react to specific substances. Further research could help us one day cure addiction as a chronic disease.
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Research continues to investigate ways to break the addictive cycle. Genetics is among the most cutting-edge investigation being carried out today into the nature of addiction. So far, this research has yielded lots of information on addiction on the genetic level and in brain processes. Researchers have managed to isolate a number of genes, hormones and chemicals in the brain that are directly related to certain types of addictions. By identifying these aspects of addiction, researchers have formed the basis that could lead to the creation of drugs that treat specific addiction.

However, geneticists aren't betting that they will find a single gene that leads to addiction in people. Research so far has shown that genetic predisposition is most likely caused by a combination of genes working together. Interestingly, research has shown that genes also play a role in making people less susceptible to addiction. Rather than simply not having genes that would make them more likely to become addicted to a substance, some people actually have genes that can keep them from ever becoming addicted.


There are already some medications in use that can treat addiction or alleviate symptoms. For many years, methadone has been used to treat heroin addiction. This drug affects the opiate receptors, and can alleviate both the physical and psychological symptoms of withdrawal. Another drug that has shown promise for treating heroin addiction, LAAM (levo-alpha-acetyl methadol), acts as an opioid antagonist, keeping opiate receptors in the brain from being stimulated, thus degrading the effect heroin has on the user.

Another prescription medication, Nalmefene, has been shown to curb gambling addiction. It's also being tested to see if it can cure alcoholism, but has shown weaker results than it has in treating gambling addiction.

The most widespread medications used to treat addiction are antidepressants. These drugs address the feelings of despair that can result from psychological dependency. They can also help treat any preexisting condition, like depression, that may have led to the addiction in the first place.

This is a good example of the holistic approach that science is currently undertaking to treat addiction. This holistic approach identifies the need to address not only the brain disease of addiction, but also the internal factors (such as genetics) and the external risk factors that lead to and enable addiction. Addiction is a multifaceted chronic disease, and it takes multifaceted treatment to restore the life of the addict to normalcy.

For more information on addiction and related topics, check out the links on the next page.


Lots More Information

Related HowStuffWorks Articles

More Great Links


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