Feeling Tipsy From Just One Glass of Wine? Here's Why.
People who feel the effects of only a drink or two have a gene that may protect them against alcoholism, researchers have learned. [via]
A team from the University of North Carolina at Chapel Hill School of Medicine found that a variant in a gene known as CYP2E1 is linked to how a person responds to alcohol.
The 10 to 20 percent of the population who have that gene variant feel tipsier after a couple of drinks than those who have a different version of the gene, according to the study authors.
Prior research has shown that people who have a low tolerance to alcohol or a strong reaction to a few drinks are less likely to become alcoholics later in life. But the genetics behind the phenomenon had been a mystery.
The discovery of the CYP2E1 variant may hold the answer, as well as clues to how the brain is affected by alcohol.
"We have found a gene that protects against alcoholism, and on top of that, has a very strong effect," senior study author Dr. Kirk Wilhelmsen, a professor of genetics at UNC, said in a statement. "But alcoholism is a very complex disease, and there are lots of complicated reasons why people drink. This may be just one of the reasons."
Researchers relied on a specific factor -- how people feel after consuming certain amounts of alcohol -- to figure out why some develop drinking problems and others don't.
Wilhelmsen and his colleagues looked at hundreds of pairs of college-aged siblings, all of whom had at least one alcoholic parent. Participants were given grain alcohol mixed with soda that equaled about three drinks. They were then asked at regular intervals to describe the effects of the alcohol on them using phrases including: I feel drunk, I don't feel drunk, I feel sleepy and I don't feel sleepy.
The scientists then performed genetic analyses called linkage and association to pinpoint the gene area that seemed to be impacting the subjects' perception of alcohol. The region they found is where the CYP2E1 gene is located.
That gene, which works in the brain, encodes an enzyme that is able to metabolize alcohol. Another called alcohol dehydrogenase that works in the liver metabolizes most of the alcohol in the body. CYP2E1 has a different mechanism than other enzymes and creates little molecules known as free radicals that can react badly to brain cells.
"It turns out that a specific version ... of CYP2E1 makes people more sensitive to alcohol, and we are now exploring whether it is because it generates more of these free radicals," Wilhelmsen said. "This finding is interesting because it hints at a totally new mechanism of how we perceive alcohol when we drink."
Dr. Petros Levounis, the director of The Addiction Institute of New York, said the research is contrary to what many people believe.
"A lot of times our younger patients feel that if they can hold their liquor and drink everyone under the table, then that's a good thing and that means they will not become alcoholics," he told AOL Health. "We get more and more and more evidence that it's the other way around. If you drink a lot and you don't feel it, on a genetic basis, that is actually a sign that you have an increased chance of becoming an alcoholic."
Levounis said the findings shed more light on where the alcoholism gene is.
"This is a gene variant that has been described in the past, but this study further pinpoints the location of this gene," he said. "This solidifies our evidence that the genetics of alcoholism seem to run parallel with the ability to have high tolerance to alcohol."
Wilhelmsen believes the discovery may lead to the use of drugs that trigger the gene to make people more sensitive to alcohol before they've tried their first drink or help them get sober if they've had too much to drink. He also said it will likely change the way research on what causes alcoholism is done.
The findings appear in the October 19 online edition of Alcoholism: Clinical and Experimental Research and will be published in print in the January issue of the journal.
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