What Is Alcoholism? – A Medical View

Alcoholism is a chronic disease, progressive and often fatal; it is a primary disorder and not a symptom of other diseases or emotional problems. The chemistry of alcohol allows it to affect nearly every type of cell in the body, including those in the central nervous system. In the brain, alcohol interacts with centers responsible for pleasure and other desirable sensations. After prolonged exposure to alcohol, the brain adapts to the changes alcohol makes and becomes dependent on it. For people with alcoholism, drinking becomes the primary medium through which they can deal with people, work, and life. Alcohol dominates their thinking, emotions, and actions. The severity of this disease is influenced by factors such as genetics, psychology, culture, and response to physical pain.

Alcoholism can develop insidiously; often there is no clear line between problem drinking and alcoholism. The only early indications of alcoholism may be the unpleasant physical responses to withdrawal that occur during even brief periods of abstinence. Sometimes people experience long-term depression or anxiety, insomnia, chronic pain, or personal or work stress that lead to the use of alcohol for relief, but often no extraordinary events have occurred that account for the drinking problem.

Alcoholics have little or no control over the quantity they drink or the duration or frequency of their drinking. They are preoccupied with drinking, deny their own addiction, and continue to drink even though they are aware of the dangers. Over time, some people become tolerant to the effects of drinking and require more alcohol to become intoxicated, creating the illusion that they can “hold their liquor.” They have blackouts after drinking and frequent hangovers that cause them to miss work and other normal activities. Alcoholics might drink alone and start early in the day. They periodically quit drinking or switch from hard liquor to beer or wine, but these periods rarely last. Severe alcoholics often have a history of accidents, marital and work instability, and alcohol-related health problems. Episodic violent and abusive incidents involving spouses and children and a history of unexplained or frequent accidents are often signs of drug or alcohol abuse.

Alcohol Use and Abuse

Experts define levels of alcohol use and abuse as follows (with a drink defined as 12 oz of beer, 6 oz of wine, or 1.5 oz of 90-proof liquor):

  • Moderate drinking: equal to or less than two drinks a day for men and equal to or less than one drink a day for women.
  • At-risk drinking: more than 14 drinks per week or 4 drinks at one sitting for men and more than seven drinks a week or three drinks at one sitting for women.
  • Alcohol abuse: one or more of the following alcohol-related problems over a period of one year: failure to fulfill work or personal obligations; recurrent use in potentially dangerous situations; problems with the law; and continued use in spite of harm being done to social or personal relationships.
  • Alcohol dependence: The individual experiences three or more of the following alcohol-related problems over a period of one year: increased amounts of alcohol needed to produce an effect; withdrawal symptoms; drinking more over a given period than intended; unsuccessful attempts to quit or cut down; giving up significant leisure or work activities; continuing drinking in spite of the knowledge of its physical or psychological harm to oneself or others.
What Causes Alcoholism?

People have been drinking alcohol for perhaps 15,000 years. Just drinking steadily and consistently over time can cause a sense of dependence and withdrawal symptoms during periods of abstinence; this physical dependence, however, is not the sole cause of alcoholism. To develop alcoholism, other factors usually come into play, including biology and genetics, culture, and psychology.

Brain Chemistry and Genetic Factors

The craving for alcohol during abstinence, the pain of withdrawal, and the high rate of relapse are due to the brain’s adaptation to and dependence on the changes in its own chemistry caused by long term use of alcohol. Alcohol causes relaxation and euphoria but also acts as a depressant on the central nervous system. Even after years of research, experts still do not know exactly how alcohol affects the brain or how the brain affects alcoholism. Alcohol appears to have major effects upon the hippocampus, an area in the brain associated with learning and memory and the regulation of emotion, sensory processing, appetite, and stress. Alcohol breaks down into products called fatty acid ethyl esters, which appear to inhibit important neurotransmitters (chemical messengers in the brain) in the hippocampus. Of particular importance to researchers of alcoholism are the neurotransmitters gamma aminobutyric acid (GABA), dopamine, and serotonin, which are strongly associated with, emotional behavior and cravings. Research indicates that dopamine transmission, particularly, is strongly associated with the rewarding properties of alcohol, nicotine, opiates, and cocaine. Investigators have focused on nerve-cell structures known as dopamine D2 receptors (DRD2), which influence the activity of dopamine. Mice with few of these receptors show low interest in and even aversion to alcohol.

In people with severe alcoholism, researchers have located a gene that alters the function of DRD2. This gene is also found in people with attention deficit disorder, who have an increased risk for alcoholism, and in people with TouretteÕs syndrome and autism. One major study, however, found no connection at all between the DRD2 gene and alcoholism. More work in this area is needed. Researchers are also investigating genes that regulate certain enzymes known as kinases that affect alcohol uptake in the brain as well as genes that affect serotonin. Even if genetic factors can be identified, however, they are unlikely to explain all cases of alcoholism. In fact, lack of genetic protection may play a role in alcoholism. Because alcohol is not found easily in nature, genetic mechanisms to protect against excessive consumption may not have evolved in humans as they frequently have for protection against natural threats.

Who Becomes an Alcoholic?

General Risks and Age

Some population studies indicate that in a single year, between 7.4% and 9.7% of the population are dependent on alcohol, and between 13.7% and 23.5% of Americans are alcohol-dependent at some point in their lives. A 1996 national survey reported that 11 million Americans are heavy drinkers (five or more drinks per occasion on five or more days in a month) and 32 million engaged in binge drinking (five or more drinks on one occasion) in the month previous to the survey. People with a family history of alcoholism are more likely to begin drinking before the age of 20 and to become alcoholic. But anyone who begins drinking in adolescence is at higher risk. Currently 1.9 million young people between the ages of 12 and 20 are considered heavy drinkers and 4.4 million are binge drinkers. Although alcoholism usually develops in early adulthood, the elderly are not exempt. In fact, in one study, 15% of men and 12% of women over age 60 drank more than the national standard for excess alcohol consumption. Alcohol also affects the older body differently; people who maintain the same drinking patterns as they age can easily develop alcohol dependency without realizing it. Physicians may overlook alcoholism when evaluating elderly patients, mistakenly attributing the signs of alcohol abuse to the normal effects of the aging process.


Most alcoholics are men, but the incidence of alcoholism in women has been increasing over the past 30 years. About 9.3% of men and 1.9% of women are heavy drinkers, and 22.8% of men are binge drinkers compared to 8.7% of women. In general, young women problem drinkers follow the drinking patterns of their partners, although they tend to engage in heavier drinking during the premenstrual period. Women tend to become alcoholic later in life than men, and it is estimated that 1.8 million older women suffer from alcohol addiction. Even though heavy drinking in women usually occurs later in life, the medical problems women develop because of the disorder occur at about the same age as men, suggesting that women are more susceptible to the physical toxicity of alcohol.

Family History and Ethnicity

The risk for alcoholism in sons of alcoholic fathers is 25%. The familial link is weaker for women, but genetic factors contribute to this disease in both genders. In one study, women with alcoholism tended to have parents who drank. Women who came from families with a history of emotional disorders, rejecting parents, or early family disruption had no higher risk for drinking than women without such backgrounds. A stable family and psychological health were not protective in people with a genetic risk. Unfortunately, there is no way to predict which members of alcoholic families are most at risk for alcoholism.

Irish and Native Americans are at increased risk for alcoholism; Jewish and Asian Americans are at decreased risk. Overall, there is no difference in alcoholic prevalence between African Americans, whites, and Hispanic people. Although the biological causes of such different risks are not known, certain people in these population groups may be at higher or lower risk because of the way they metabolize alcohol. One study of Native Americans, for instance, found that they are less sensitive to the intoxicating effects of alcohol. This confirms other studies, in which young men with alcoholic fathers exhibited fewer signs of drunkenness and had lower levels of stress hormones than those without a family history. In other words, they “held their liquor” better. Experts suggest such people may inherit a lack of those warning signals that ordinarily make people stop drinking. Many Asians, on the other hand, are less likely to become alcoholic because of a genetic factor that makes them deficient in aldehyde dehydrogenase, a chemical used by the body to metabolize ethyl alcohol. In its absence, toxic substances build up after drinking alcohol and rapidly lead to flushing, dizziness, and nausea. People with this genetic susceptibility, then, are likely to experience adverse reactions to alcohol and therefore not become alcoholic. This deficiency is not completely protective against drinking, however, particularly if there is added social pressure, such as among college fraternity members. It is important to understand that, whether it is inherited or not, people with alcoholism are still legally responsible for their actions.

Emotional Disorders

Severely depressed or anxious people are at high risk for alcoholism, smoking, and other forms of addiction. Major depression, in fact, accompanies about one-third of all cases of alcoholism. It is more common among alcoholic women (and women in general) than men. Interestingly, one study indicated that depression in alcoholic women may cause them to drink less than nondepressed alcoholic women, while in alcoholic men, depression has the opposite effect. Depression and anxiety may play a major role in the development of alcoholism in the elderly, who are often subject to dramatic life changes, such as retirement, the loss of a spouse or friends, and medical problems. Problem drinking in these cases may be due to self-medication of the anxiety or depression. It should be noted, however, that in all adults with alcoholism these mood disorders may be actually caused by alcoholism and often abate after withdrawal from alcohol.

Personality Traits

Studies are finding that alcoholism is strongly related to impulsive, excitable, and novelty-seeking behavior, and such patterns are established early on, if not inherited. People with attention deficit hyperactivity disorder, a condition that shares these behaviors, have a higher risk for alcoholism. Children who later become alcoholics or who abuse drugs are more likely to have less fear of new situations than others, even if there is a risk for harm. In a test of mental functioning, alcoholics (mostly women) did not show any deficits in thinking but they were less able to inhibit their responses than nonalcoholics. It was once thought that a family history of passivity and abnormal dependency needs increased the risk for alcoholism, but studies have not borne out this theory.

Socioeconomic Factors

It has been long thought that alcoholism is more prevalent in people with lower educational levels and in those who were unemployed. A thorough 1996 study, however, reported that the prevalence of alcoholism among adult welfare recipients was 4.3% to 8.2%, which was comparable to the 7.4% found in the general population. There was also no difference in prevalence between poor African Americans and poor whites. People in low-income groups did display some tendencies that differed from the general population. For instance, as many women as men were heavy drinkers. Excessive drinking may be more dangerous in lower income groups; one study found that it was a major factor in the higher death rate of people, particularly men, in lower socioeconomic groups compared with those in higher groups.

Geographic Factors

Although 54% of urban adults use alcohol at least once a month compared to 42% in nonurban areas, living in the city or the country does not affect the risks for bingeing or heavy alcohol use. One study reported that people in the north central U.S. are at highest risk for heavy drinking (6.4% heavy use and 19% binge drinking) and those in the Northeast have the lowest risk (4.5% heavy use and 13% binge drinking).

Sugar Cravings

People who crave sugar may also be at higher risk for alcoholism. In one recent study, 62% of male alcoholics enjoyed a sweet sugar solution compared with only 21% of those without a drinking problem. It is not known, however, whether having a “sweet tooth” can be an early predictor of alcoholism or whether alcohol abusers simply develop a taste for sweetness as a result of their chronic alcohol abuse.

How Serious Is Alcoholism?

About 100,000 deaths a year can be wholly or partially attributed to drinking, and alcoholism reduces life expectancy by 10 to 12 years. Next to smoking, it is the most common preventable cause of death in America. Although studies indicate that adults who drink moderately (about one drink a day) have a lower mortality rate than their non-drinking peers, their risk for untimely death increases with heavier drinking. Any protection that occurs with moderate alcohol intake appears to be confined to adults over 60 who have risks for heart disease. The earlier a person begins drinking heavily, the greater their chance of developing serious illnesses later on. Alcoholism can kill in many different ways, and, in general, people who drink regularly have a higher rate of deaths from injury, violence, and some cancers.


Alcohol overdose can lead to death. This is a particular danger for adolescents who may want to impress their friends with their ability to drink alcohol but cannot yet gauge its effects.

Accidents, Suicide, and Murder

Alcohol plays a major role in more than half of all automobile fatalities. Less than two drinks can impair the ability to drive. Alcohol also increases the risk of accidental injuries from many other causes. One study of emergency room patients found that having had more than one drink doubled the risk of injury, and more than four drinks increased the risk eleven times. Another study reported that among emergency room patients who were admitted for injuries, 47% tested positive for alcohol and 35% were intoxicated. Of those who were intoxicated, 75% showed evidence of chronic alcoholism. This disease is the primary diagnosis in one quarter of all people who commit suicide, and alcohol is implicated in 67% of all murders.

Domestic Violence and Effects on Family

Domestic violence is a common consequence of alcohol abuse. Research suggests that for women, the most serious risk factor for injury from domestic violence may be a history of alcohol abuse in her male partner. Alcoholism in parents also increases the risk for violent behavior and abuse toward their children. Children of alcoholics tend to do worse academically than others, have a higher incidence of depression, anxiety, and stress and lower self-esteem than their peers. One study found that children who were diagnosed with major depression between the ages of six and 12 were more likely to have alcoholic parents or relatives than were children who were not depressed. Alcoholic households are less cohesive, have more conflicts, and their members are less independent and expressive than households with nonalcoholic or recovering alcoholic parents. In addition to their own inherited risk for later alcoholism, one study found that 41% of children of alcoholics have serious coping problems that may be life long. Adult children of alcoholic parents are at higher risk for divorced and for psychiatric symptoms. One study concluded that the only events with greater psychological impact on children are sexual and physical abuse.

Medical Problems

Alcohol can affect the body in so many ways that researchers are having a hard time determining exactly what the consequences are of drinking. It is well known, however, that chronic consumption leads to many problems, some of them deadly.

Heart Disease

Large doses of alcohol can trigger irregular heartbeats and raise blood pressure even in people with no history of heart disease. A major study found that those who consumed more than three alcoholic drinks a day had higher blood pressure than teetotalers. The more alcohol someone drank, the greater the increase in blood pressure. People who were binge drinkers had the highest blood pressures. One study found that binge drinkers (people who have nine or more drinks once or twice a week) had a risk for a cardiac emergency that was two and a half times that of nondrinkers. Chronic alcohol abuse can also damage the heart muscle, which leads to heart failure; women are particularly vulnerable to this disorder. Contrary to many previous reports, a recent study suggested that moderate to heaving drinking (more than two bottles of beer or two glasses of wine day) was a greater risk factor for coronary artery disease than smoking. As in other studies, light drinking (two to six drinks a week) was protective. More research is needed to confirm or refute this new study. In any case, moderate drinking does not appear to offer any heart benefits for people who are at low risk for heart disease to begin with.


Alcohol may not cause cancer, but it probably does increase the carcinogenic effects of other substances, such as cigarette smoke. Daily drinking increases the risk for lung, esophageal, gastric, pancreatic, colorectal, urinary tract, liver, and brain cancers, lymphoma and leukemia. About 75% of cancers of the esophagus and 50% of cancers of the mouth, throat, and larynx are attributed to alcoholism. (Wine appears to pose less danger for these cancers than beer or hard liquor.) Smoking combined with drinking enhances risks for most of these cancers dramatically. When women consume as little as one drink a day, they may increase their chances of breast cancer by as much as 30%.

Liver Disorders

The liver is particularly endangered by alcoholism. About 10% to 35% of heavy drinkers develop alcoholic hepatitis, and 10% to 20% develop cirrhosis. In the liver, alcohol converts to an even more toxic substance, acetaldehyde, which can cause substantial damage. Not eating when drinking and consuming a variety of alcoholic beverages are also factors that increase the risk for liver damage. People with alcoholism are also at higher risk for hepatitis B and C, potentially chronic liver diseases than can lead to cirrhosis and liver cancer. People with alcoholism should be immunized against hepatitis B; they may need a higher-than-normal dose of the vaccine for it to be effective.

Gastrointestinal Problems

Alcohol can cause diarrhea and hemorrhoids. Alcohol can also contribute to serious infections of the pancreas and to ulcers in people taking the painkillers known as nonsteroidal anti-inflammatory drugs (such as aspirin or ibuprofen).

Pneumonia and Other Infections

Alcohol suppresses the immune system, so people with alcoholism are prone to infections. In particularly, acute alcoholism is strongly associated with very serious pneumonia. One study on laboratory animals suggests that alcohol specifically damages the bacteria-fighting capability of lung cells.

Mental and Neurologic Disorders

Alcohol has widespread effects on the brain. One study that scanned the brains of inebriated subjects suggested that while alcohol stimulates those parts of the brain related to reward and induces euphoria, it does not appear to impair cognitive performance (the ability to think and reason). Habitual use of alcohol, however, eventually produces depression and confusion. In chronic cases, gray matter is destroyed, possibly leading to psychosis and mental disturbances. Alcohol can also cause milder neurologic problems, including insomnia and headache (especially after drinking red wine). Except in severe cases, neurologic damage is not permanent and abstinence nearly always leads to recovery of normal mental function. Alcohol may increase the risk for hemorrhagic stroke (caused by bleeding in the brain), although it may protect against stroke caused by narrowed arteries.

Skin, Muscle, and Bone Disorders

Severe alcoholism is associated with osteoporosis, wasting away of muscles with swelling and pain, skin sores, and itching. In addition, alcohol-dependent women seem to face an increased risk for damage to muscles, including muscles of the heart, from the toxic effects of alcohol.

Hormonal Effects

Alcoholism increases levels of the female hormone estrogen and reduces levels of the male hormone testosterone, factors that contribute to impotence in men.


Alcoholics who smoke face compound their health problems. More alcoholics die from tobacco-related illnesses, such as heart disease or cancer, than from chronic liver disease, cirrhosis, or other conditions more directly tied to excessive drinking.


Alcohol can cause hypoglycemia, a drop in blood sugar, which is especially dangerous for people with diabetes who are taking insulin. Intoxicated diabetics may not be able to recognize symptoms of hypoglycemia, a particularly hazardous condition.

Malnutrition and Wernicke-Korsakoff Syndrome

A pint of whiskey provides about half the daily calories needed by an adult, but it has no nutritional value. In addition to replacing food, alcohol may also interfere with absorption of proteins, vitamins, and other nutrients. Of particular concern in alcoholism is a severe deficiency in the B-vitamin thiamin, which can cause a serious condition called Wernicke-Korsakoff syndrome. Symptoms of this syndrome include severe loss of balance, confusion, and memory loss. Eventually, it can result in permanent brain damage and death. Another serious nutritional problem among alcoholics is deficiency of the B vitamin folic acid, which can cause severe anemia.

Acute Respiratory Distress Syndrome

One study indicated that intensive care patients with a history of alcohol abuse have a significantly higher risk for developing acute respiratory distress syndrome (ARDS) during hospitalization. ARDS is a form of lung failure that can be fatal. It is can by caused by many of the medical conditions common in chronic alcoholism, including severe infection, trauma, blood transfusions, pneumonia, and other serious lung conditions.

Drug Interactions

The effects of many medications are strengthened by alcohol, while others are inhibited. Of particular importance is its reinforcing effect on antianxiety drugs, sedatives, antidepressants, and antipsychotic medications. Alcohol also interacts with many drugs used by diabetics. It interferes with drugs that prevent seizures or blood clotting. It increases the risk for gastrointestinal bleeding in people taking aspirin or other nonsteroidal inflammatory drugs including ibuprofen and naproxen. In other words, taking almost any medication should preclude drinking alcohol.

Pregnancy and Infant Development

Even moderate amounts of alcohol may have damaging effects on the developing fetus, including low birth weight and an increased risk for miscarriage. High amounts can cause fetal alcohol syndrome, which can result in mental and growth retardation. One study indicates a significantly higher risk for leukemia in infants of women who drink any type of alcohol during pregnancy.

Complications in Older People

As people age, it takes fewer drinks to become intoxicated, and organs can be damaged by smaller amounts of alcohol than in younger people. Also, up to one-half of the 100 most prescribed drugs for older people react adversely with alcohol.

Well-Connected Board of Editors
Harvey Simon, M.D., Editor-in-Chief
Massachusetts Institute of Technology; Physician, Massachusetts General Hospital
Masha J. Etkin, M.D., Gynecology
Harvard Medical School; Physician, Massachusetts General Hospital
John E. Godine, M.D., Ph.D., Metabolism
Harvard Medical School; Associate Physician, Massachusetts General Hospital
Daniel Heller, M.D., Pediatrics
Harvard Medical School; Associate Pediatrician, Massachusetts General Hospital; Active Staff, Children’s Hospital
Irene Kuter, M.D., D. Phil., Oncology
Harvard Medical School; Assistant Physician, Massachusetts General Hospital
Paul C. Shellito, M.D., Surgery
Harvard Medical School; Associate Visiting Surgeon, Massachusetts General Hospital
Theodore A. Stern, M.D., Psychiatry
Harvard Medical School; Psychiatrist and Chief, Psychiatric Consultation Service, Massachusetts General Hospital
Carol Peckham, Editorial Director
Cynthia Chevins, Publisher