Brookhaven study: Nondrinkers from alcoholic families may be better able to sense internal reward
A brain receptor that helps regulate pleasure and motivation is at higher-than-normal levels in people who don't drink but have a strong family history of alcoholism, according to a new study.
Scientists at Brookhaven National Laboratory in Upton made the discovery through doing brain scans on 15 young adults who are nondrinkers and have at least three first-degree family members with histories of alcohol abuse.
Earlier research conducted at the lab has found that levels of the same brain receptor, called dopamine-2, is lower than normal in alcoholics. Scientists suspect that the lower number of dopamine receptors may prevent alcoholics from feeling intrinsic pleasure, which may motivate them to drink. Similarly, scientists say the higher levels of dopamine-2 receptors in nondrinkers may somehow protect these at-risk people from excessive drinking.
The implications of this discovery might lead to new ways to treat alcohol addiction, scientists say.
According to Dr. Gene-Jack Wang, chairman of the lab's medical department and lead author of the study in the Archives of General Psychiatry, scientists have used gene therapy to increase dopamine-2 receptors in rats primed for alcohol addiction. They stopped drinking. When the new receptors were depleted, the animals resumed their consumption of liquor.
The thinking, Wang said, is that high levels of this receptor appear to inhibit the need for alcohol - at least, in the animals they've studied. The receptor levels may provide enough internal reward signals so the animals don't need to artificially enhance their brain's reward system.
Low levels of dopamine-2, on the other hand, may lead to alcohol abuse as a way to compensate for stress or a weaker reward area. Whether a similar process occurs in humans is not known.
"The fact that we can see differences in dopamine-2 receptors in people who drink and in those who don't could point to a genetic influence," explained Dr. David Goldman, chief of the laboratory of neurogenetics at the National Institute on Alcohol Abuse and Alcoholism. "But there may be other differences in behavior and experience that can also alter dopamine function."
It is too early to know what factors are really at work.
In the latest study, the 15 nondrinkers from alcoholic families were compared to 16 nondrinkers from families with no history of alcoholism. They used a brain scan with a radioactive tracer to visualize the dopamine-2 receptor system. Each person in the study also filled out a personality questionnaire to determine whether they are introverts or extroverts.
Wang, who collaborated with Dr. Nora Volkow, director of the National Institute on Drug Abuse, said they found that people with the most dopamine-2 receptors were also more extroverted, independent of their family history of alcoholism.
Interestingly, Wang said one treatment that appears to help alcoholics is to increase their social networks.
Experts say that just because someone has a genetic risk does not mean that they will become a drinker. There are many other factors that come into play.
BY JAMIE TALAN
Newsday Staff Writer, excerpt from Newsday
