Alcoholism
Description
An in-depth report on the causes, diagnosis, and treatment of alcoholism.
Alternative Names
Alcohol dependence, Alcohol abuse
Causes
People have been drinking alcohol for about 15,000 years. Drinking steadily and consistently over time can produce dependence and cause 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, genetics, culture, and psychology.
Genetic Factors
Genetic factors play a significant role in alcoholism and may account for about half of the total risk for alcoholism. The role that genetics plays in alcoholism is complex, however, and it is likely that many different genes are involved. Recent research suggests that alcohol dependence, and other substance addictions, may be associated with genetic variations in 51 different chromosomal regions.
Researchers are investigating a number of inherited traits that make particular individuals susceptible to this disorder:
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The amygdala is an area of the brain thought to play a role in the emotional aspects of craving, which can lead to addiction. Some studies indicate that the amygdala is smaller in subjects with family histories of alcoholism, suggesting that inherited differences in brain structure may affect risk. Other studies suggest that certain brain chemicals (neurotransmitters) and proteins in the amygdala region may be involved in the link between anxiety and alcoholism.
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Some evidence indicates that a lack of genetic protection plays a major role in alcoholism. Such studies have found that people with a family history of alcoholism tend to "hold their liquor" better than those without such a history. Experts suggest some people may inherit a lack of those warning signals that ordinarily make people stop drinking. Research suggests this factor may contribute to 40 - 60% of alcoholism cases related to genetic factors. (Even in the absence of genetic factors, repeated exposure to alcohol increases the ability to tolerate larger amounts before experiencing behavioral impairment.)
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Genes that regulate certain chemical byproducts of alcohol are under intense scrutiny. Alcohol is metabolized in a two-stage process: It is first converted to
acetaldehyde (AcH)
, which is then converted into
acetate
. AcH is being researched because it plays a role in most actions of alcohol, including damaging effects on the liver and upper airway. It also may be protective. For example, some people, particularly in some Asian and Jewish populations, may be less likely to become alcoholic because of a genetic deficiency in AcH, which produces a buildup of acetate after drinking alcohol. Acetate is toxic and in high amounts causes flushing, dizziness, and nausea. Individuals with this genetic factor, then, are less likely to become alcoholic. (This deficiency is not completely protective against drinking, however, particularly if there is social pressure and high exposure to alcohol, such as among college fraternity members.)
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Some people with alcoholism may have an inherited dysfunction in the transmission of serotonin. Serotonin is a brain chemical messenger (neurotransmitter). It is important for well-being and associated behaviors (eating, relaxation, and sleep). Abnormal serotonin levels are associated with high levels of tolerance for alcohol. They are also linked to impulsivity and aggressiveness. These behaviors can predispose people to drink and can increase the risk for dangerous behaviors and suicide in people who are alcohol dependent.
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Dopamine is another neurotransmitter associated with alcoholism and other addictions. Research indicates that high levels of the D2 dopamine receptor may help inhibit behavioral responses to alcohol, and protect against alcoholism, in people with a family history of alcohol dependence.
Even if genetic factors can be identified, however, they are unlikely to explain all cases of alcoholism. It is important to understand that whether they inherit the disorder or not, people with alcoholism are still legally responsible for their actions. Inheriting genetic traits does not doom a child to an alcoholic future. Environment, personality, and emotional factors also play a strong role.
Brain Chemical Imbalances After Long-Term Alcohol Use
Alcohol has widespread effects on the brain and can affect neurons (nerve cells), brain chemistry, and blood flow within the frontal lobes of the brain. Researchers are particularly interested in systems of neurotransmitters (chemical messengers) in the brain that are affected by alcohol. Some research is focusing on the way these neurotransmitters are employed in the brain after long-term alcohol use in order to adapt to the cravings and pain of withdrawal. Such chemical changes may lead to dependency or to relapse after quitting in two ways:
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They increase the need to reduce agitation.
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They increase the desire to restore pleasurable feelings.
Reducing Agitation.
When a person who is dependent on alcohol stops drinking, the following chemical responses create an overexcited nervous system and agitation:
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A drop in gamma-aminobutyric acid (GABA), a brain chemical that inhibits impulsivity
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An increase in glutamate, a brain chemical that excites nerve cells
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An increase in norepinephrine and corticotropin releasing factor, hormones linked to stress
High norepinephrine levels, in fact, may be the primary factor in withdrawal symptoms such as an increase in blood pressure and heart rate. This hyperactivity in the brain produces an intense need to calm down and to use more alcohol. One study suggested that the need to relieve agitation may be the more important factor in causing a relapse than restoring mood.
Restoring Pleasure.
Alcohol stimulates the release of neurotransmitters and other chemicals that produce the following pleasurable feelings:
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Dopamine produces euphoria and a sensation of being rewarded. Repeated alcohol use increases sensitivity to dopamine.
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Serotonin produces feelings of well-being.
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Opioid peptides are important for well-being.
Over time, however, heavy alcohol use appears to deplete the stores of dopamine and serotonin. Persistent drinking, therefore, eventually fails to restore mood, but by then the drinker has been conditioned to
believe
that alcohol will improve spirits (even though it does not).
Social and Emotional Causes of Alcoholic Relapse
Between 80 - 90% of people treated for alcoholism relapse, even after years of abstinence. Patients and their caregivers should understand that relapses of alcoholism are analogous to recurrent flare-ups of chronic physical diseases. According to one study, three factors placed a person at high risk for relapse:
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Frustration and anger
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Social pressure
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Internal temptation
Another study suggests that impaired sleep is also an important predictor of relapse.
Mental and Emotional Stress.
Alcohol blocks out emotional pain and is often perceived as a loyal friend when human relationships fail. It is also associated with freedom and with a loss of inhibition that offsets the tedium of daily routines. When the alcoholic tries to quit drinking, the brain seeks to restore what it perceives to be its equilibrium. The brain's best weapons to achieve this are depression, anxiety, and stress (the emotional equivalents of physical pain), which are produced by brain chemical imbalances. These negative moods continue to tempt alcoholics to return to drinking long after physical withdrawal symptoms have abated.
Even intelligence is no ally in this process, for the over-agitated brain will use all its powers of rationalization to persuade the patient to return to drinking. According to one study, having a high or low IQ has little effect on quitting. However, according to this study, a high verbal ability may aid the alcoholic in remaining sober.
It is important to realize that any life change, even changes for the better, may cause temporary grief and anxiety. With time and the substitution of healthier pleasures, this emotional turmoil weakens and can be overcome.
Co-dependency.
Many aspects of the ex-drinker's relationships change when drinking stops, making it difficult to remain abstinent:
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One of the most difficult problems that occur is being around other people who are able to drink socially without danger of addiction. A sense of isolation, a loss of enjoyment, and the ex-drinker's belief that pity, not respect, is guiding a friend's attitude can lead to loneliness, low self-esteem, and a strong desire to drink again.
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Friends may not easily accept the sober, perhaps more subdued, ex-drinker. Close friends and even intimate partners may have difficulty in changing their responses to this newly sober person and, even worse, may encourage a return to drinking.
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To preserve marriages, spouses of alcoholics often build their own self-images on surviving or handling their mates' difficult behavior and then discover that they are threatened by abstinence.
In such cases, separation from these "enablers" may be necessary for survival. It is no wonder that, when faced with such losses, even if they are temporary, a person returns to drinking. The best course in these cases is to encourage close friends and family members to seek help as well. Fortunately, groups such as Al-Anon exist for this purpose.
Social and Cultural Pressures.
The media portrays the pleasures of drinking in advertising and programming. The medical benefits of light-to-moderate drinking are frequently publicized, giving ex-drinkers the spurious excuse of returning to alcohol for their health. These messages must be categorically ignored and acknowledged for what they are: An industry's attempt to profit from potentially great harm to individuals.
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Review Date: 12/3/2006
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Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital
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