MARINA DEL REY, Calif. -- Genetic factors play a major role in the development of alcoholism in women, contrary to the findings of many previous studies, according to a Virginia researcher.
The new findings also indicate that alcoholism is becoming more common in women, probably as a result of the relaxation of cultural inhibitions.
In a new study of 1,030 sets of female twins, the researchers found that genetics control 50 percent to 60 percent of women's susceptibility to alcoholism, with cultural and environmental factors accounting for the rest.
The researchers say that their results, reported yesterday at a medical conference here and in today's issue of the Journal of the American Medical Association, are more reliable than those of previous studies because they are based on much larger numbers of women. Furthermore, they are nearly identical to similar findings recently reported in men and suggest that genetics play an equal role in both sexes.
Women also seem to be approaching men in the extent of their drinking problems. Past estimates have suggested that only about 3 percent of American women develop severe drinking problems during their lifetimes (and about 14 percent of the entire population). But the researchers found that fully 9 percent of the women in their study, all below the age of 30, suffered from alcoholism and another 8.3 percent from problem drinking.
"Women in this new generation are beginning to drink just like their fathers did and they are going to suffer all the problems associated with alcoholism that their fathers did," said Dr. Robert Cloninger, a psychiatric geneticist at Washington University in St. Louis.
"This is an excellent study and a very important result," said behavioral geneticist Matt McGue of the University of Minnesota, who reported in 1981 that he found no genetic contribution to women's susceptibility to alcoholism. "This is certainly going to revise the way I think about things."
"The take-home message from this study," said its primary author, Dr. Kenneth S. Kendler, a psychiatrist at Virginia Commonwealth University in Richmond, "is that the biomedical community needs to rethink its position on alcoholism in women." A much greater proportion of women should be included in alcoholism studies that have previously focused primarily on men, he argued.
Dr. Kendler and his colleagues at Washington University and the University of Michigan studied 1,030 female twin pairs from the Virginia Twin Registry. Each twin was interviewed personally by social workers.
In general, they found that if one member of a set of identical twins had a problem with alcohol, her twin was four to five times more likely to suffer the same problem than were women in the general population. In contrast, if one member of a set of fraternal twins has an alcohol problem, the second twin was only 1.5 to two times as likely as other women to suffer the problem.
Using well-established statistical techniques, Dr. Kendler and his colleagues were able to calculate that genetics made a 50 percent to 60 percent contribution to the alcohol problems. "This means that genes are not trivial [in determining susceptibility to alcoholism], but they are not of overwhelming importance either," Dr. Kendler said. "They don't dictate completely whether you will or will not become an alcoholic."
Several controversial studies have suggested that alcoholism is associated with a particular gene called the D2 dopamine receptor, but most evidence suggests D2 is only one of several that genes may be responsible for inherited susceptibility.
Dr. Kendler noted that his study group was much larger than those in previous twin studies "and thus more likely to be accurate."
Equally surprising, perhaps, was the study's finding that fully 17 percent of the young women had a drinking problem, much higher than in previous reports but in line with other studies now under way.