People with close relatives who are alcoholics appear to feel the "high" of alcohol more intensely, indicating a genetic link to the disease, researchers in Indiana say.

11/24/2002

Although it's well known that the sons and daughters of alcoholics are prone to heavy drinking, researchers have had a hard time pinpointing exactly why.

Some studies suggest that alcoholics' genes impart a heightened sensitivity to the pleasures of a drink. Other experiments imply that people inherit a physical tolerance: they're able to hold their liquor, in effect, because they're less sensitive to the drug's effects than the average person.

A study published recently may help resolve the confusion.

Researchers at Indiana University School of Medicine measured the effects of alcohol on 116 adult social drinkers, who normally averaged about four drinks a week. Half the subjects had at least two close relatives who were diagnosed as alcoholics; the other half had no known family history of heavy drinking. Both groups were given a dose of alcohol intravenously, equivalent to about two drinks, and asked to rate the drug's intoxicating effects.

All immediately felt the sensation of the booze. But those with a family history rated their intoxication level as significantly higher than the group without the drinking pedigree. "They appeared to feel the alcohol 'high' more intensely, at the beginning of the test," says Sandra Morzorati, a professor of psychiatry and the study's lead author.

An hour later, however, the high had faded. Although the level of alcohol in their blood was unchanged, the subjects with a family history of alcoholism had adapted; they now felt no more intoxicated than the others, says Morzorati.

"We think that this could mean that people with a family history develop a tolerance for alcohol because they drink more to maintain the same effect they had earlier," she says. "That initial high goes away, and they drink more to get the feeling back."

One reason researchers have had difficulty measuring responses to alcohol is that each person absorbs a drink at his or her own rate. In some, the alcohol

moves from the stomach to the brain quickly; in others, it takes more time.

Morzorati got around this problem by administering the alcohol intravenously, and monitored blood-alcohol levels continually. "This allows for a direct comparison of the effects, at a specific blood-alcohol level," says Robert Pihl, an alcoholism researcher at McGill University in Montreal.

Genes may underlie how we think about the sensations of drinking, researchers say. In previous studies, people closely related to alcoholics have shown themselves to be very sensitive to positive sensations, such as euphoria, and less to negative effects, such as tiredness, Pihl says. By contrast, those with no family history of alcoholism appear more likely to report the negative sensations, he says.

About 1 in 10 Americans who drink regularly go on to develop habits that cause them serious problems, and about 1 in 20 become heavily dependent, alcoholic drinkers, according to government statistics. An estimated 20 percent to 25 percent of sons or brothers of alcoholics develop serious drinking problems; and about 5 percent of alcoholics' daughters or sisters do.

"The next step in research is to look at the genetic contribution to drinking behavior," Morzorati says. "To see, for example, if those with a family history enjoy the drug more if they're drinking faster."