Why Some People May Be More Prone To Alcoholism Than Others

By Paul Gaita 06/28/18

A landmark study may have pinpointed a gene that is linked to alcoholism.

Silhouette of a man holding a bottle of alcohol

New research may provide further clues into how genetics play a role in the development of dependency on drugs and alcohol.

A new study used rats that had been fed a steady diet of alcohol as test subjects; when offered more alcohol or a saccharine solution, a small but significant number continued to choose alcohol over the more preferable sweet offering, even when the choice meant that they would receive an electric shock.

Upon examining the rats' brains, the researchers found that the rats that chose alcohol had lower levels of a certain gene that controlled the release of a chemical linked to alcohol dependence.

The study's findings suggest that the gene may be the first step toward a greater understanding of, and even treatment for, alcohol dependency.

The study published in the June 22, 2018 edition of Science, was conducted by a multinational group of researchers from the University of Illinois, Chicago, University of Texas, Austin and Sahlgrenska Academy at the University of Gothenburg, Sweden.

A test group of 32 rats was trained to consume a 20% alcohol solution for 10 weeks until it became a habit for the animals; they were then presented a daily choice of more alcohol or a solution of the artificial sweetener saccharine. 

What they found was that the majority of the rats preferred the sugar option over alcohol—a common trait among mammals, as Scientific American noted, because sugar can be easily converted into calories and provide energy for survival. But four rats (12.5% of the study group) chose the alcohol every time, even under the threat of receiving an electric shock if they made that choice.

Additional testing confirmed the scientists' suspicions. "600 animals later, we found that a very stable population chose alcohol," said senior study author Markus Heilig, director of the Center for Social and Affective Neuroscience at Linkoping in Sweden.

From there, the scientists examined the brains of the rodent subjects, and found that a gene called GAT-3 was expressed to a much lesser degree in the brains of the rats that chose alcohol.

As Scientific American noted, GAT-3 is linked to a protein that controls the levels of GABA, a major inhibitory neurotransmitter in the brain and one linked with dependency on alcohol. 

Further research found that brain samples from deceased humans who had exhibited alcohol dependency also showed lower levels of GAT-3 in the amygdala, which is widely considered to be the brain's center for emotions and in particular, fear.

Heilig told Scientific American that it makes sense that the lowered levels would be found there and not in the brain's reward center.

"The rewarding effect of drugs happens in everybody," he said. "It's a completely different story in the minority of people who continue to take drugs [and use alcohol] despite adverse consequences."

Heilig and his team have begun work on a treatment for addiction based on their research; according to Scientific American, the drug suppresses the release of GABA, which could reduce the compulsion to consume alcohol in the face of dangerous circumstances. They are currently working with a pharmaceutical company in hopes of launching tests of their compound on humans.

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Paul Gaita lives in Los Angeles. He has contributed to the Los Angeles Times, Variety, LA Weekly, Amazon.com and The Los Angeles Beat, among many other publications and websites.