The Role of Heredity in Alcoholism
Like many other diseases, alcoholism is influenced by both hereditary and environmental factors that are being increasingly well defined. Experts now believe that alcoholism arises from a wide range of physiological, psychological, social and genetic factors.
Alcoholism tends to run in families, and genetic factors partially explain this pattern. Researchers are looking for the genes that influence vulnerability to alcoholism. They are also exploring the relationship between genetics and environment.
Genetic risk to alcoholism, however, is not destiny. A child of an alcoholic parent will not automatically develop alcoholism, and a person with no family history of alcoholism can become alcohol dependent.
Children of Alcoholics (COAs)
According to the National Clearinghouse for Alcohol and Drug Information (NCADI), children of alcoholics generally:
Regardless of whether COAs are raised by alcoholics, they are at risk for alcoholism or alcoholism-related problems. However, the good news is that COAs can learn to trust, handle their feelings in healthy ways, and build positive, nurturing relationships, all of which help protect them from alcohol problems. While you cannot change your genes, you can change your unhealthy living patterns and how you deal with outside pressures.
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This article was last updated on 07/01/2003
This article was reviewed January 2003, by Simeon Margolis, M.D.,Ph.D., Professor of Medicine, Endocrinology and Biologic Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD.
Alcohol and Heredity
Some of us have inherited characteristics that make alcoholization more likely. The children of alcoholics become alcoholized more often than the children of non-drinkers. This is because the predisposition to alcoholism is hereditary, not because of the influence of environmental factors. Science is searching for methods for recognizing individuals at risk of alcoholism already in childhood. This would provide us with the possibility of preventing alcoholism.
The effects of the environment and of hereditary factors have been studied. A Swedish study revealed that sons of an alcoholic biological parent were, compared to others, twice as likely to become alcoholics, whereas the risk did not increase for adoptive children of alcoholized foster parents. Nothing indicated that imitating the behaviour of parents would be a significant factor in adopting alcoholic drinking habits.
The effect of hereditary factors is also evident in drinking habits and intoxication. The drinking habits of identical twins are more alike than those of fraternal twins. According to and American study, identical twins may even take to the same brands of alcoholic beverages. They also become intoxicated in the same way.
Laboratory animals provide a reliable method of research. The environmental factors are the same for all of them. Over twenty years ago, in Alko's research laboratory, two types of rats were bred: rats that consumed a lot of alcohol, and rats that were sober. Their descendants were also drinkers or sober, respectively.
Rats can also be bred to tolerate alcohol differently. In Alko's research laboratory, there are rats that become more intoxicated than other rats on the same amount of alcohol. Also these laboratory tests prove the importance of hereditary factors in alcoholism. It wouldn't even be possible to breed rats with different drinking habits or varying tolerance for alcohol if these traits were not hereditary.
It is not yet known what it is in alcoholism that is hereditary. Few expect the researchers to find a gene responsible for alcoholism, determining whether an individual will become an alcoholic or not. Instead, researchers try to define a hereditary biological characteristic that predisposes some for alcoholism. This is one of the great challenges of biomedical research on alcohol.
If we find out what it is that causes the drinker rats in Alko's laboratory to like alcohol, we might be close to revealing the secrets of alcoholism. This knowledge would give us the possibility to find those individuals who are predisposed to alcoholism before alcohol becomes a problem for them. Measures could be taken to protect them from alcoholism and the development of a problem could be prevented.
Research professor Kalervo Kiianmaa, National Public Health Institute
Unlocking the Genetic Mysteries of Alcoholism
By Paula Moyer
May 19, 2000 (Chicago) -- We all know heredity plays a big part in alcoholism. We've seen the patterns that run in families: Johnny is an alcoholic, just like his dad and his dad before him. But how important is heredity? Do we learn bad -- and good -- habits from our parents, or are they preprogrammed in us, passed down in our genetic makeup?
This is the same question medical researchers have been trying to answer for many years. Every now and again, someone makes a small discovery that helps us understand who we are and what made us that way. New research presented here at the 153rd annual meeting of the American Psychiatric Association (APA) does just that.
According to researcher Patricia I. Ordorica, MD, something called OPRMI -- a particular genetic version of a molecule known to trap chemical impulses in the brain -- may explain why some people are more prone to become hooked on alcohol. In a recent study, Ordorica examined a group of alcoholics and found they are 2.5 times more likely to have the bad version of the OPRMI gene than are nonalcoholics -- including people who never drink as well as those who drink socially but don't get addicted.
Investigators are also curious to know whether a genetic tendency to alcoholism might make a person more likely to become addicted to other substances, such as tobacco. Therefore, Ordorica and her colleagues looked at whether the addiction-connected form of OPRMI was commonly found in smokers.
Importantly, they found that smokers were no more likely to have the substance in their bodies, which seems to mean that this particular gene is specifically connected to alcoholism.
"[T]hese results are another reason to be optimistic about our increasing knowledge of the major public health problem of alcoholism," says Ordorica, who is associate chief of staff for mental health and behavioral sciences at the Tampa VA Medical Center and director of addictive disorders at the University of South Florida.
"Although we are learning that genetic factors [are] important in the development of this illness, a lot of people still think that these are bad people," she says. "While no one gene causes alcoholism, genetic factors clearly account for a significant amount of the risk for the development of alcoholism."
Genetic research on alcoholism adds to the understanding of the illness and also points out its complexity, the APA's outgoing president Allan Tasman, MD, tells WebMD. Tasman, who has a background in addiction research, was not involved in Ordorica's study.
"We don't know whether a genetic deficit has been passed on," he says, "or if it's the environment, or some combination of the two." His hunch is that it's unlikely that just one gene is responsible for making someone an alcoholic. It's much more likely, he says, that several genetic traits are involved and work together to lead to the disease.
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