A solid study led by researchers at the University of Linköping has discovered a molecular mechanism in the brain that is considered essential for the development of alcohol addiction. The research explains that why some people are more addicted to alcohol than others and they may even lead to a new drug therapy that could treat alcohol dependence.
“We have to understand that a central characteristic of addiction is that you know it’s going to hurt you, potentially you can even kill it, and yet something has gone wrong with motivational control and it continues to do so,” says Markus Heilig, co Director lead in the new study.
Therefore, the researchers set out to better understand what is happening in the brain that leads to a choice despite the negative consequences. An experiment with rats was organized in which the animals were given a free choice between sweetened water and alcohol. Alcohol, activated by pushing a lever, was harder for the animals to access than sweetened water.
After a period of time, it was observed that only about 15 percent of the rats continued to work harder to obtain the alcohol on the sweetened water. Interestingly, the researchers note that this percentage is similar to the number of humans suffering from alcohol addiction. When the scientists added a small electric discharge to the lever that supplied the alcohol, they observed that the rats were still looking for the substance.
So, what was different between the rats that were looking for alcohol despite the negative consequences and the rats that did not?
After measuring the expression of hundreds of specific genes in alcoholic rats, the researchers focused on one particular gene. Located in the amygdala, a region of the brain previously implicated in alcohol dependence, it is known that this gene regulates a protein called GAT-3.
“Decreasing the expression of the transporter had a surprising effect on the behavior of these rats. The animals that choose sweet taste over alcohol are turned their preferences and they began to choose alcohol,” says Eric Augier.
Finally, the study aimed to find some correlation in humans by examining GAT-3 levels in the tonsil tissue samples of individuals who died with alcoholism. Exclusively, the results confirmed that these people who suffered from alcoholism showed lower levels of GAT-3 than normal human substances.
“This is one of those relatively rare moments where we found an interesting change in our animal models and found the same change in the brains of human alcoholics,” says Dayne Mayfield, co-author of the new study. “It’s a very good sign that our animal model is correct, and if our animal model is correct, we can examine the therapeutics with it and get more confidence in the findings.”
One thing that is not clear at this stage is what leads a person to develop lower levels of GAT-3. It could be simply genetic, or it could be a more complex series of environmental factors that stimulate a deficiency in this neurological mechanism. Either way, this is an informative research that adds weight to the argument that alcohol addiction is not a psychological condition, but a more complete neurological disease.