Why do some people binge drink? It may be in their genes.
Researchers from King's College London's Institute of Psychiatry have previously discovered that the RASGRF2 gene is linked to alcohol abuse. A study published in the Proceedings of the National Academy of Sciences on Dec. 3 now shows how that gene affects alcoholics.
The RASGRF-2 gene works to control how the brain releases dopamine, a chemical neurotransmitter that makes people feel pleasure and reward. Alcohol and other addictive substances stimulate the brain's dopamine system.
"So, 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," lead author Gunter Schumann, professor of biological psychiatry, said in a press release.
One out of six people in the United States has a drinking problem, the National Institutes of Health report.
In 2009, 10.4 million people between the ages of 12 and 20 admitted to drinking more than a few sips of alcohol, according to the National Institute of Alcohol Abuse and Alcoholism. By age 15, 70 percent of teens have had at least one drink. More than 190,000 people under the age of 21 went to the emergency room for an alcohol-related injury in 2008 alone. Five thousand people under 21 die each year from alcohol-related car crashes, homicides, suicides, alcohol poisoning, and other injuries such as falls, burns, and drowning.
People who are at risk of becoming alcoholics are men who have 15 or more drinks a week, or women who have 12 or more drinks a week, according to the National Institutes of Health. Anyone who has five or more drinks per occasion at least once a week is also at risk. On average, while young adults drink less often than adults they drink five drinks on a single occasion.
Young adults under peer pressure, people with history of depression and other mental disorders, easy access of alcohol, low self-esteem, problems with relationships, stressful lifestyles and those who live in a culture where drinking is common and accepted have a higher chance of developing alcoholism.
The study first looked at mice without the RASGRF-2 gene to see how alcohol affected them. They found these mice had significantly lowered alcohol-seeking behavior because the lack of the gene partially blocked their brains from releasing dopamine -- the reward sensation -- from an area of the brain called the ventral tegmental area (VTA).
Researchers then scanned the brains of 663 14-year-old boys who had not been exposed to large amounts of alcohol. Individuals who had a certain genetic variation of the RASGRF2 gene had more activation in their VTA region, meaning more dopamine was released when they were looking forward to a reward from a cognitive task. This meant that their brains released more dopamine when they were about to receive something good, giving them more happiness from that experience.
They then followed up with the same group of boys when they were 16 years old. Many of them had began to drink alcohol. Those who had the variation on the RASGRF2 drank more frequently than those without the variation.
"Identifying risk factors for early alcohol abuse is important in designing prevention and treatment interventions for alcohol addiction," Schumann said.
Dr. Dominique Florin, medical director of the Medical Council on Alcohol, told the BBC that any research that helps us understand alcoholism is helpful.
"It's likely that there is a genetic component to problem drinking, but that's not to say that if you have this gene you should never touch alcohol or if you don't have the gene then it will be fine for you to drink," Florin said.