Claims of a genetic basis for alcoholism, a leading theorist argues, are not scientifically supportable and ignore the crucial link between personal values and self-destructive or antisocial behavior

Morristown, New Jersey

Major news stories about discoveries of the genetic sources of emotional and behavioral problems surface every year or so. Since 1987 such reports have appeared on the front page of The New York Times in connection with manic-depressive disorder, schizophrenia, and alcoholism. Last year, however, the Times published a story titled "Scientists Now Doubt They Found Faulty Gene Linked to Mental Illness." This story received less attention than the announcements of positive findings, for it appeared not on the front page of the newspaper but buried deep inside. The article revealed that both new data and further analysis of the original data "cast serious doubt" on the earlier finding that a defective gene was, in fact, associated with manic-depressive disorder. The article furthermore noted that "the new findings underscore the difficulty of assigning specific causes to such a complex and variable illness," and that problems also plague efforts to identify precisely any sort of genetic role in schizophrenia. One of the authors of the original study said, "We are sort of back to square one."

The Blum-Noble "Alcoholism Gene"

The study that the Times reported linking alcoholism to a specific gene was published in the Journal of at American Medical Association on April 18 of this year, as the journal's lead article. It was accompanied by press releases, a highly publicized news conference in Los Angeles, and video interviews with the study's authors, which the AMA transmitted by satellite in its weekly television news release. The study's chief authors were Kenneth Blum, a pharmacologist at the University of Texas Health Science Center, in San Antonio, and Ernest Noble, a psychiatrist and biochemist at the UCLA Alcohol Research Center and a former director of the National Institute of Alcohol Abuse and Alcoholism.

Unlike the manic-depressive-disorder and schizophrenia studies, which were conducted within individual families or communities, the alcoholism study involved seventy unrelated cadavers, thirty-five of which had been alcoholics and thirty-five of which were controls. According to the researchers, the alcoholic cases were of an extremely "virulent" type—many of the thirty-five people had died of cirrhosis. Genetic material from all seventy brains was analyzed. A genetic marker was found in 69 percent of the alcoholics in the study but in only 20 percent of the nonalcoholics.

Blum and Noble concluded that the Al "allele," or variant, of the dopamine D2 receptor gene was associated with alcoholism. Dopamine is one of a number of neurotransmitters, or chemicals produced in the body that convey information throughout the nervous system. Neurotransmitters communicate by attaching to receptors on nerve cells which are tailored specifically to them. One important question not answered by the gene discovery is exactly what dopamine receptors, the physiological mechanisms affected by the gene, have to do with alcoholism. Another question is how this discovery fits in with what has previously been established about the heritability of alcoholism.

Theories of the Heritability of Alcoholism

The dopamine receptor gene is not clearly implicated in the major existing genetic theories of human alcoholism. According to these theories, a certain personality type predisposes a minority of male problem drinkers to both crime and alcoholism; an inherited insensitivity to alcohol allows alcoholics to drink more while being less aware of the effects of the alcohol they are consuming; alcoholics are not able to metabolize alcohol normally; and alcoholics have inherited neurological and intellectual dysfunctions. Not only are the originators of some of these theories the sole researchers to have found evidence to support them, but also several of the theories and findings directly contradict the premises or reasoning of others.

The inherited-personality theory has been promoted by a research group at the School of Medicine at Washington University, in St. Louis, under the direction of Robert Cloninger, a psychiatrist. This may be the most popular current notion about how alcoholism is inherited. However, it must face the formidable difficulties involved in associating entire personality syndromes, such as criminality, with particular genes.

The idea that alcoholics inherit an insensitivity to alcohol has been presented by Mark Schuckit, a psychiatrist at the University of California at San Diego Medical School. Another research team (led by Barbara Lex, of Harvard Medical School) has supported Schuckit's hypothesis in a study comparing small numbers of women from alcoholic and nonalcoholic families. But James Wilson and Craig Nagoshi, of the University of Colorado, in a much larger study, found the lessened sensitivity to alcohol to hold for some age-and-sex groups among offspring of alcoholics but not for others.

Schuckit also at one time presented evidence that alcoholism results from an inherited flaw in the way alcoholics metabolize alcohol. According to this theory, alcoholics' bodies do not break down alcohol properly and, as a result, build up abnormal levels of acetaldehyde (one of the products of alcohol's oxidization) when they drink.

The acetaldehyde hypothesis got strong play in the widely read book Under the Influence, by James Milam and Katherine Ketcham, which was published in 1981. Milam and Ketcham forcefully argued that acetaldehyde is a primary biological and genetic basis for alcoholism, which they claimed is completely biologically determined. However in recent years researchers have lost enthusiasm for this model, which has been contradicted by subsequent research. For example, several research teams investigating the offspring of alcoholics were unable reliably to identify abnormal acetaldehyde buildups after their subjects consumed alcohol. Schuckit himself no longer focuses on acetaldehyde as the most likely mechanism for the heritability of alcoholism.