|Vol. 5, No. 1, 1999 Page 1&6|
A new, large-scale study adds to evidence that genes play a major role in alcoholism and problem drinking.
Carol Prescott and Kenneth Kendler studied 3,516 fraternal or identical male twins, obtaining their subjects from a twin registry in Virginia. Twin studies are a useful way to measure genetic influences on behavior, because identical twins share the same genetic makeup, while fraternal twins share only half their genes.
While previous studies have focused on severe forms of alcoholism, Prescott and Kendler say that "these cases account for only a small proportion of the morbidity and social costs associated with misuse of alcohol." Thus, Prescott and Kendler examined gen netic and environmental effects on both overt alcoholism and less severe drinking problems.
"Like other twin and adoption studies of alcoholism in males," the researchers report, "we found evidence for substantial genetic influences." This was true, they say, for both alcoholism and less severe alcohol abuse. Conversely, the researchers found li iittle evidence that shared family environment contributes to the development of alcohol problems. Prescott and Kendler determined that 50 percent or more of the variation in susceptibility to alcohol-related problems is due to genetic factors, with nonsh hared environment playing a smaller role.
In a similar study in 1997, Kendler, Prescott, and colleagues studied 8,935 Swedish male twin pairs born before 1950. In that study, the researchers identified subjects who had registered with temperance boards because their drinking problems had led to l llegal or medical intervention. The Swedish study found that "the similarity in twins for temperance board registration was significantly greater in monozygotic [identical] than in dizygotic [fraternal] twins," again showing a strong genetic influence on alcohol abuse.
A number of studies by other research groups (see related article, Crime Times, 1997, Vol. 3, No. 1, Page 1&3&7) also have provided strong evidence that alcoholism is, to a great degree, "in the genes." Studies indicate, for instance, that children of alcoholics are approximately four times as likely to become alcoholics as are children of non-alcoholics, even when n the children of alcoholics are separated from their biological parents at birth and raised by non-alcoholic parents.
"Genetic and environmental contributions to alcohol abuse and dependence in a population-based sample of male twins," Carol A. Prescott and Kenneth S. Kendler, American Journal of Psychiatry, Vol. 156, No. 1, January 1999, pp. 34-40. Address: Carol l Prescott, Virginia Institute for Psychiatric and Behavioral Genetics, Medical College of Virginia, Virginia Commonwealth University, P.O. Box 980126, Richmond, VA 23298-0126.
"Temperance board registration for alcohol abuse in a national sample of Swedish male twins, born 1902 to 1949," Kenneth S. Kendler, Carol A. Prescott, Michael C. Neale, and Nancy L. Pedersen, Archives of General Psychiatry, Vol. 54, February 1997, pp. 178-184. Address: Kenneth S. Kendler, Department of Psychiatry, Medical College of Virginia, Virginia Commonwealth University, P.O. Box 980710, Richmond, VA 23298-0710.