How Alcoholism Works

Alcoholism affects millions of people in the United States. Witthaya Prasongsin / Getty Images


We've all seen the stereotypical "drunk" in movies and television shows: He's the one staggering down the street, clothing askew, slurring his words and tripping over his own feet. But in the real world, alcoholism is often much more difficult to spot. Alcoholics may hide their drinking problem from friends, family -- even from themselves.


In the United States alone, alcoholism affects millions of people and costs the country billions of dollars each year.

In this article, we'll learn the difference between heavy drinking and alcoholism, find out how alcohol affects the body, discover the genetic, social and physiological factors that lead individuals down the path to alcoholism and learn how alcoholics can get treatment for their addiction.

But first, what is alcoholism?


What is Alcoholism?

Most people can enjoy the occasional glass of wine with dinner or beer out with friends. But for other people, one drink becomes two drinks, which becomes four drinks -- they are unable to stop drinking.

Not everyone who drinks alcohol heavily is considered an alcoholic. People who drink regularly enough to affect their family or work responsibilities and who drink in a way that puts them in dangerous situations (for example, behind the wheel of a car while intoxicated) are said to abuse alcohol. Although they use alcohol in an unhealthy way, people who suffer from alcohol abuse do not necessarily develop a physical dependence upon alcohol.


Alcoholics, on the other hand, have a chronic disease. They are physically dependent upon alcohol. They feel a need to drink, almost in the same way that most people feel the need to eat. And once alcoholics start drinking, they are unable to stop. They develop a tolerance to alcohol, requiring more and more drinks to feel the same effects. When an alcoholic tries to cut down or stop drinking, he or she experiences the symptoms of withdrawal: sweating, nausea, shakiness, anxiety and delirium tremens (seeing images, severe shaking, confusion).

More than 17 million Americans abuse alcohol or are alcoholic, according to results from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Alcoholism affects men more than women: About 10 percent of men, compared to 3 to 5 percent of women, become alcoholics over the course of their lifetime. Men who drink 14 or more drinks a week and women who drink more than seven drinks per week are at risk for alcoholism. Alcoholism is more prevalent among younger people (ages 18-44) than among older people.

How Does Someone Become an Alcoholic?

Why is it that some people can drink socially and not become addicted while others become alcoholics? The reason has to do with a combination of genetic, physiological, psychological and social factors.

Genes may be an important factor triggering the development of alcoholism. Research has indicated that children of alcoholics are four times more likely to become alcoholics themselves; and while this statistic is at least partly due to environmental factors, scientists have determined that there is a genetic link. Researchers are working to pinpoint exactly which genes increase a person's risk of becoming an alcoholic in order to develop new medications to treat alcoholism.


Physiologically, alcohol alters the balance of chemicals in the brain. It affects chemicals in the brain's reward center, such as dopamine. The body eventually craves alcohol to restore pleasurable feelings and avoid negative feelings. People who already suffer from high stress or psychological problems such as low self esteem and depression are at higher risk for developing alcoholism.

Social factors such as peer pressure, advertising and environment also play an important role in the development of alcoholism. Young people often start drinking because their friends are doing so. Beer and liquor ads on television tend to portray drinking as a glamorous, exciting pastime.

Signs that someone might be an alcoholic include:

  • Drinking to forget his or her problems
  • Drinking alone often
  • Lying about his or her drinking habits
  • Losing interest in food
  • Feeling unhappy or irritable when he or she is not drinking
  • Losing memories of certain events ("blacking out")

What Happens When You Drink

How alcohol is absorbed in the body

When you take a drink, about 20 percent of the alcohol is absorbed in your stomach; the remaining 80 percent is absorbed in your small intestine. How quickly the alcohol is absorbed depends upon the concentration of the alcohol in the drink (vodka, for example, will be absorbed faster than beer, because vodka has a higher alcohol concentration) and whether you've just eaten a big meal. A full stomach will slow down alcohol absorption.

After the alcohol is absorbed, it enters your bloodstream and is carried throughout your body. As the alcohol acts upon the body, the body is simultaneously working to remove it. The kidneys and lungs remove about 10 percent of the alcohol in the urine and the breath (which is why a breathalyzer test can be used to measure a person's blood alcohol level). The liver breaks down the rest of the alcohol into acetic acid.


After just a few drinks, the physical effects of alcohol become apparent. These effects are related to the blood alcohol concentration (BAC). The BAC goes up when the body is taking in alcohol faster than it can release it. To learn about specific impairments at various BAC levels, see How Alcohol Works: The Effects of Alcohol.

Alcohol and the Brain

Most of us have witnessed the outward signs of heavy drinking: the stumbling walk, slurred words and memory lapses. People who have been drinking have trouble with their balance, judgment and coordination. They react slowly to stimuli, which is why drinking before driving is so dangerous. All of these physical signs occur because of the way alcohol affects the brain and central nervous system.

Alcohol affects brain chemistry by altering levels of neurotransmitters. Neurotransmitters are chemical messengers that transmit the signals throughout the body that control thought processes, behavior and emotion. Neurotransmitters are either excitatory, meaning that they stimulate brain electrical activity, or inhibitory, meaning that they decrease brain electrical activity. Alcohol increases the effects of the inhibitory neurotransmitter GABA in the brain. GABA causes the sluggish movements and slurred speech that often occur in alcoholics. At the same time, alcohol inhibits the excitatory neurotransmitter glutamate. Suppressing this stimulant results in a similar type of physiological slowdown. In addition to increasing the GABA and decreasing the glutamate in the brain, alcohol increases the amount of the chemical dopamine in the brain's reward center, which creates the feeling of pleasure that occurs when someone takes a drink.


Summary of alcohol's effects on the brain - Move your cursor over the colored bar in the lower left-hand corner to see which areas of the brain are affected by increasing BAC.

Alcohol affects the different regions of the brain in different ways:

  • Cerebral cortex: In this region, where thought processing and consciousness are centered, alcohol depresses the behavioral inhibitory centers, making the person less inhibited; it slows down the processing of information from the eyes, ears, mouth and other senses; and it inhibits the thought processes, making it difficult to think clearly.
  • Cerebellum: Alcohol affects this center of movement and balance, resulting in the staggering, off-balance swagger we associate with the so-called "falling-down drunk."
  • Hypothalamus and pituitary: The hypothalamus and pituitary coordinate automatic brain functions and hormone release. Alcohol depresses nerve centers in the hypothalamus that control sexual arousal and performance. Although sexual urge may increase, sexual performance decreases.
  • Medulla: This area of the brain handles such automatic functions as breathing, consciousness and body temperature. By acting on the medulla, alcohol induces sleepiness. It can also slow breathing and lower body temperature, which can be life threatening.

In the short term, alcohol can cause blackouts -- short-term memory lapses in which people forget what occurred over entire stretches of time. The long-term effects on the brain can be even more damaging.

Alcohol and the Brain: In the Long Run

Long-term drinking can leave permanent damage, causing the brain to shrink and leading to ­deficiencies in the fibers that carry information between brain cells. Many alcoholics develop a condition called Wernicke-Korsakoff syndrome, which is caused by a deficiency of thiamine (a B vitamin). This deficiency occurs because alcohol interferes with the way the body absorbs B vitamins. People with Wernicke-Korsakoff syndrome experience mental confusion and lack of coordination, and they may also have memory and learning problems.

The body responds to the continual introduction of alcohol by coming to rely on it. This dependence causes long-term, debilitating changes in brain chemistry. The brain accommodates for the regular presence of alcohol by altering neurotransmitter production. But when the person stops or dramatically reduces his or her drinking, within 24 to 72 hours the brain goes into what is known as withdrawal as it tries to readjust its chemistry. Symptoms of withdrawal include disorientation, hallucinations, delirium tremens (DTs), nausea, sweating and seizures.


To learn more about how alcohol affects the brain, see How Alcohol Works.

Alcohol and the Rest of the Body

Areas of the body affected by alcoholism

Drinking excessive amounts of alcohol can seriously harm your health, damaging the liver, kidneys, heart, brain and central nervous system.

We already discussed long-term damage to the brain. Over time, alcohol can inflict serious damage on other body parts as well.


  • Liver: The liver is particularly vulnerable to the effects of alcohol because it is the organ in which alcohol and other toxins are metabolized (broken down into less harmful substances to be removed from the body). Drinking over a long period of time can lead to alcoholic hepatitis, or inflammation of the liver. Symptoms of this condition include nausea, vomiting, fever, loss of appetite, abdominal pain and jaundice (a yellowing of the skin). Up to 70 percent of people with alcoholic hepatitis develop cirrhosis. With this condition, healthy liver tissue is replaced by scar tissue, which eventually renders the liver unable to function.


Cirrhotic liver
Photo courtesy National Library of Medicine
  • Stomach: Alcohol irritates the lining of the stomach and intestines, causing vomiting, nausea and eventually ulcers.
  • Pancreas: The pancreas releases the hormones insulin and glucagon, which regulate the way food is broken down and used for energy by the body. Long-term drinking can lead to inflammation of the pancreas (pancreatitis).
  • Cancer: Research indicates that long-term drinking increases the risk of cancers of the mouth, throat, larynx and esophagus.

The effects of alcohol are even more marked in adults over 65, because their bodies don't metabolize alcohol as well as those of younger adults. Women also have more difficulty metabolizing alcohol than men, because they are typically smaller and lighter in weight. Also, alcohol can be deadly when combined with certain medications, such as pain killers, tranquilizers and antihistamines.

Treatment for Alcoholism

In the United States, approximately 2 million people get help each year for alcoholism. Alcoholism treatment may include:

  • Detoxification: This involves abstaining from alcohol in order to get alcohol completely out of a person's system, and it takes anywhere from four to seven days. People who undergo detoxification often take medications to prevent delirium tremens and other symptoms of withdrawal.
  • Pharmaceuticals: People can take drugs such as disulfiram or naltrexone to prevent a relapse once they've stopped drinking. Naltrexone reduces the desire to drink by blocking the centers in the brain that feel pleasure when alcohol is consumed. Disulfiram causes a severe physical reaction to alcohol that includes nausea, vomiting and headaches. In 2004, the U.S. Food & Drug Administration also approved the drug acamprosate, which suppresses cravings by targeting the brain chemicals affected by alcohol.
  • Counseling: Individual or group counseling sessions can help a recovering alcoholic identify situations in which they may be tempted to use alcohol and find ways of circumventing the urge to drink in those situations. One of the most recognizable alcoholic recovery programs is Alcoholics Anonymous (AA). In this 12-step program, recovering alcoholics meet regularly to support one another through the recovery process.

The effectiveness of these programs varies depending upon the severity of the problem, the social and psychological factors involved and the individual's commitment to the process. A 2001 study found that 80 percent of people who had gone through a 12-step program such as AA remained abstinent six months afterward, compared to about 40 percent of people who didn't go through a program. Studies have also found that combining medication with therapy works better than either treatment alone. Medication addresses the chemical imbalances that cause alcohol addiction, while therapy helps people cope with abstinence.


Unfortunately, there is no "cure" for alcoholism. Recovering alcoholics must continually work to prevent a relapse. However, a 2001-2002 survey by the National Institutes of Health found that approximately 35 percent of alcoholic adults were able to fully recover from their addiction.

For more information on alcoholism, including treatment resources, check out the links on the next page.

Lots More Information

Related HowStuffWorks Articles

More Great Links

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