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A novel strategy for tackling alcoholism

In a new study, researchers have found a region on chromosome 1 that may lead certain people to begin drinking alcohol heavily late in life and to feel guilty and anxious about their drinking.

The scientists adopted a novel strategy for finding genes involved in alcohol use and problematic drinking: They identified patterns of drinking in alcoholics and social drinkers and tried to link these patterns to regions of the human genome.

They categorized behavior in people with a variety of libation habits—including substance abusers and non-alcoholics. Previous studies have often focused only on people who are addicted to alcohol.

"You lose a lot of information when you group people into 'affected' or 'unaffected' groups in terms of alcoholism," says Danielle Dick, who led the research at Indiana University School of Medicine in Indianapolis.

"There is a lot of information to be gained when you study patterns of drinking across all individuals who drink, not just alcoholics," she adds.

Dick and colleagues interviewed more than 9,000 people about their drinking habits, including at what age they started drinking, whether physical fights and arguments arise when imbibing, and whether they had any feelings of guilt, depression and anxiety about drinking.

The researchers also ranked each drinker's cautiousness, inhibition, shyness, dependence on others for acceptance, and streaks of impulsiveness and excitability.

Based on this analysis, the scientists found that drinking patterns fell into three groups: They characterized the first group as people who begin drinking at an earlier age, are thrill seekers and have a variety of drinking-related problems. The second group includes people who begin drinking later in life and are more cautious and anxious. The last group are people who greatly depend on the acceptance of others.

The scientists were able to strongly link one of the patterns—drinking at a late age and with high anxiety—to chromosome 1. To do this, they tracked the inheritance of genetic markers in a subset of families that were most densely affected with alcoholism, they write in the journal Alcoholism: Clinical and Experimental Research.

Alcoholism is influenced by both genes and environment, according to P. Michael Conneally, an alcoholism researcher also at Indiana.

Adoption studies have shown children adopted away from alcoholics have a four times greater risk of developing alcoholism than other adopted kids, said Conneally, while speaking in October at the annual meeting of the American Society of Human Genetics, of which he is president.

Dick says, that in addition to genetics, environment also plays a large role in the inheritance of alcoholism. The environment can moderate genetic influences, which is one of the reasons why it is so difficult to find genes involved in alcoholism.

For example, if you're raised with a strict religion that prohibits drinking you're never exposed to alcohol, says Dick, "it doesn't matter what genes you carry, you probably won't become an alcoholic."

"Right now, there's really no consensus about the best way to define traits for alcohol-related behaviors," notes Dick.

The study is part of a larger project called the Collaborative Studies on Genetics of Alcoholism (COGA), which was launched 13 years ago and is operated at six universities throughout the country.

See related GNN article
»Genome scans and maximum number of drinks consumed in 24 hours indicate alcoholism hotspot on chromosome 4

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Dick, D.M. et al. Suggestive linkage on chromosome 1 for a quantitative alcohol-related phenotype. Alcohol Clin Exp Res 26, 1453-1460 (October 2002).

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