Sunday, February 14, 2010
Alcoholism: The Genetic Puzzle
Fathers and Sons.
The hunt for genetic influences on alcoholism derives largely from the work of Dr. Donald W. Goodwin, chair of the Department of Psychiatry at the University of Kansas Medical Center. Starting in the early 1970s, Dr. Goodwin and co-workers, using computer technology and a detailed database of Scandinavian health records, scrutinized the results of 5,000 adoption cases in Copenhagen. The results of the initial study stunned alcoholism experts around the world. The sons of alcoholics were more likely to become alcoholics themselves, as many had expected. But the relationship held true even when the children of alcoholics were separated from their natural parents shortly after birth, and subsequently raised by foster parents.
In Phase 2 of the Danish studies, Goodwin selected only alcoholic families in which one son had been raised by his biological parents, while the other son had been adopted away early in life. Raised in separate environments, twins of this sort are highly prized for genetic research. Goodwin compared the sons who had been raised by their alcoholic birth parents to their adopted-away brothers. It didn’t seem to make any difference: Rates of alcoholism were roughly the same. Environmental factors alone did not seem to account for it.
“By their late twenties or earlier,” Goodwin wrote, “the offspring of alcoholics had nearly twice the number of alcohol problems and four times the rate of alcoholism as the children whose parents had no record of hospitalization for alcoholism.” It did not look like family environment was the primary determinant.
Perhaps some of the children simply ended up with less effective foster parents, detractors pointed out. Alternatively, some unknown trauma might have been inflicted in the womb. Maybe the pregnant mother drank. Environmental factors can never be ruled out. Nonetheless, the basic implications of Goodwin’s work could not be shaken off. The Danish adoption studies were the first major scientific papers to establish a firm link between heredity and alcoholism.
Beginning in the 1980s, Dr. C. Robert Cloninger, professor of psychiatry and genetics at Washington University in St. Louis, and Michael Bohman, a Swedish pediatrician, began a broader series of adoption studies. The Stockholm Adoption Study scrutinized the records of more than 3,000 adopted individuals, and confirmed the Danish studies: The children of alcoholics, when compared with the children of non-alcoholic parents, were far more likely to become alcoholics themselves—even if they were adopted away.
Moreover, “Alcohol abuse in the adoptive parents was not associated with an increased risk of abuse in the children they reared,” Cloninger later reported in the journal Science, “so there was no evidence that alcoholism is familial because children imitate their [non-biological] parents.”
Adapted from The Chemical Carousel: What Science Tells Us About Beating Addiction by Dirk Hanson © 2008.
Graphics Credit: http://www.3dscience.com/