The Science of Addiction
The United States is a nation of addicts. According to a 2001 survey conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA), there are 16 million drug users, 13 million heavy drinkers, and 66 million smokers in the United States. That doesn't include the overeaters, gamblers, compulsive exercisers, and the sex obsessed. Yet most people are able to eat, drink, and exercise without becoming addicted to those activities. Why?
Neuroscientists define addiction in medical terms as "a brain disease . . . a chronic, relapsing disease."
There are 3 related stages in addiction:
Stage 1: Acute Drug Effect
- At this early stage, the individual experiences the rewarding effects of the addictive drug. Dopamine is the key brain chemical involved at this stage.
Stage 2: Transition to Addiction
- At this stage, the individual transitions from recreational use to actual addiction. Glutamine is the key brain chemical involved at this stage.
Stage 3: End Stage Addiction: At the final stage, the individual
- Experiences a strong urge to get the addictive drug
- Loses control of the drug-seeking desire
- Experiences a diminished pleasure after using the addictive drug
Scientists have worked out the two major pathways in the brain responsible for addiction. First, there is the mesolimbic pathway mediated by dopamine. Second, the prefrontal cortex, the decision-making center, is responsible for controlling any inappropriate reward responses. It has been clearly shown that drug addiction can lead to physical changes in these pathways.
Neuro-imaging techniques like
The Dopamine Connection
The biological link among all addictions is dopamine. This brain chemical is released during pleasurable activities ranging from sex and eating to more detrimental behaviors such as drinking and drug taking. "If a drug or an activity produces a sharp spike in dopamine, the odds are phenomenal that people will like it, they'll experience it as pleasurable, and it will be addictive," says Alan Leshner, PhD, of the National Institute on Drug Abuse.
A powerful drug like crack cocaine elevates dopamine levels much faster than normal pleasurable activities. It creates the classic drug-induced feelings of exhilaration and power. In a landmark 1950s experiment, scientists stimulated rodent brains and found that the animals kept returning to the place where they received the stimulation.
Coming down from a drug high is caused by a decrease in dopamine levels. If you force brain cells to produce excessive dopamine on a regular basis, they become stressed and produce less dopamine. Over time, addicts become depressed and need drugs just to stimulate dopamine to normal levels. They become trapped in a cycle of cravings and addiction to avoid withdrawal symptoms and depression.
Leshner believes that once a person crosses the line from user to addict, the brain is so changed that he can no longer control his behavior. " . . . The truth is, addiction is not a voluntary behavior. It's actually a different state," he explains. "It's hard for people to understand that, but if you take drugs to the point of addiction, functionally you move into a different state. A state of compulsive, uncontrollable drug use."
This transformation helps explain why it's so difficult to break an addiction. "There is no motivator more powerful than the drug craving and the need for them," says Leshner. Cravings are more significant than physical withdrawal in keeping an addict hooked. Drugs like cocaine and methamphetamine, unlike heroin and alcohol, don't produce intense physical withdrawal symptoms, but they do produce overpowering cravings. These cravings can be aroused by external or internal stimuli that are as innocuous as walking by a pub or feeling sad, according to Patricia Owen, PhD, director of Research and Development at the Hazelden Foundation in Minnesota.
An Addictive Personality?
Although researchers have tried to determine the type of person who becomes an addict, they have failed to identify an "addictive personality," according to Owen. It is only after people become addicts that certain common personality traits emerge, like "difficulty delaying gratification, self-centeredness, lack of concentration, and impatience," says Owen.
Sol, a former alcoholic and drug addict turned addiction counselor and administrator at a major treatment facility, feels that using a term like addictive personality "paints a hopeless picture. Some people are very compulsive, but they can change," he says. Indeed, according to Owen, 60% of addicts use both alcohol and drugs, and 80% of alcoholics also smoke.
Many addiction professionals believe addiction stems from a combination of biological, psychological, and environmental factors. "The Alcoholics Anonymous 'Big Book' describes alcoholism as a physical, emotional, and spiritual disease. They were aware of the physiological affects before we were able to do PET scans to actually see the changes," says Owen.
The progression to addiction can develop this way: Sue may have a genetic or biological predisposition to an addiction. If she grows up in a family and environment without addiction or stress, she may never begin even casual use. However, if Sue grows up in a stressful family or an environment where substance abuse is common and encounters more stresses as an adult and over time, she may move from casual to regular use to full-blown addiction.
We know that children of alcoholics have a four times higher risk of becoming alcoholics themselves than the offspring of non-alcoholics. Scientists are also studying whether addicts are born with inadequate endorphins, the brain chemicals that regulate stress.
To be an addict means that addiction has overwhelmed your entire existence. "When you speak to drug addicts about their experiences, they'll tell you that there is nothing in their life but drugs," says Leshner. So breaking an addiction often involves major lifestyle changes. For Sol, it meant losing most of his friends who were also addicts. He also had to cope with feelings that he had suppressed for years with drugs. "Using drugs prevents you from learning to handle emotions. You don't go through the maturation process," he explains.
Willpower is not a factor in quitting since addiction also impairs that faculty. That is why Leshner calls it a "relapsing disease." Most addicts who seek treatment relapse several times before they kick the habit.
For years, heroin and narcotics addictions have been treated successfully with methadone, which eases withdrawal and blocks the effect of drugs. Naltrexone is another drug commonly used for alcohol and narcotics addiction.
A new drug, buprenorphine, has shown promising results in treating narcotics addicts. Useful for detoxification, buprenorphine (usually combined with naltrexone) can also be used for maintenance therapy. Buprenorphine has less associated “high” than does methadone and can be prescribed by psychiatrists and other doctors who have received brief special training. Methadone, in contrast, can only be dispensed from a specially licensed clinic. On another front, scientists are working on a cocaine "vaccine," which could be used to inoculate addicts who relapse.
It is unlikely, however, that a magic pill will ever be found that "cures" addiction. "No matter what you do with medication, I believe that you will always need psychological treatment to provide support and manage behavior," says Jan Kaufman, Director of Substance Abuse Treatment at the North Charles Foundation in Cambridge, Massachusetts.
On the other hand, aerobic exercise offers a simple and natural way to help combat addiction. During aerobic exercise, dopamine levels are increased in the areas of the brain involved with addiction, and feelings of
Drug and alcohol problems can affect every one of us regardless of age, sex, race, marital status, place of residence, income level, or lifestyle.
You may have a problem with drugs or alcohol, if:
- You can't predict whether or not you will use drugs or get drunk.
- You believe that you need to drink and/or use drugs in order to have fun.
- You turn to alcohol and/or drugs after a confrontation or argument, or to relieve uncomfortable feelings.
- You need to drink more or use more drugs to get the same effect as previously.
- You drink and/or use drugs by yourself.
- You have periods of memory loss.
- You have trouble at work, in school, or in your personal relationships because of drinking or using drugs.
- You make promises to yourself or others that you'll stop getting drunk or using drugs but are unable to keep them.
- You feel alone, scared, miserable, and depressed.
Adapted from "Just the Facts" published by the US Substance Abuse and Mental Health Services Administration.
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Substance Abuse and Mental Health Services Administration website. Available at: http://www.samhsa.gov/ . Accessed on June 20, 2003.
Last reviewed January 2009 by
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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