Alcoholism - Causes

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:

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.

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.)

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.)

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.

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.