One in six U.S. adults binge drinks four times a month, consuming an average of eight drinks per session according to the Centers for Disease Control and Prevention — and it’s practically a rite of passage on college campuses across the country. But why do some people feel so compelled to throw back a few drinks while others have no interest at all?

Blame it on the genes. According to a new study published in the Proceedings of National Academy of Sciences, researchers have found a gene that plays a starring role in how alcohol stimulates the brain to release dopamine, triggering feelings of happiness and reward.

"If people have a genetic variation of the RASGRF-2 gene, alcohol gives them a stronger sense of reward, making them more likely to be heavy drinkers," said Gunter Schumann, who led the study at King's College London's Institute of Psychiatry.

The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as a pattern of drinking that brings a person’s blood alcohol concentration to 0.08 grams percent or above, which means about five or more drinks for men, and four or more drinks for women, in about two hours.

In the study, scientists examined mice without the RASGRF-2 gene to see how they reacted to alcohol. They found the lack of RASGRF-2 was linked to much less alcohol-seeking behavior. Upon consuming alcohol, these gene-missing mice had limited dopamine release and thus, a decreased sense of reward.

The team then went on to study brain scans of 663 14-year-old boys and discovered that when they were expecting a reward for a mental task, those with genetic variations to the RASGRF-2 gene had more activity in the area of the brain that activates dopamine release. The researchers concluded that people with a genetic variation on the RASGRF-2 gene release more dopamine when anticipating a reward, and then derive more pleasure from it.

Two years later, the scientists examined the drinking patterns of the same boys and found that those with the RASGRF-2 gene variation drank more often at the age of 16 than those without it. Schumann explained that while this is not proof that the gene causes binge drinking, the findings help shed light on why some people appear to be vulnerable to the allure of alcohol.

"This appears to be one gene that regulates how rewarding alcohol is for some people. People seek out situations which fulfill their sense of reward and make them happy, so if your brain is wired to find alcohol rewarding, you will seek it out.”

Related alcohol story on MNN: Even moderate alcohol consumption disrupts sleep

Scientists discover binge-drinking gene
New findings help shed light on why some people appear to be more vulnerable to alcohol's magnetic pull.