While performing research on brain changes related to binge drinking, scientists at the Salk Institute may have stumbled upon a test to predict whether compulsive drinking will occur.
Alcohol Use Disorder
Have you ever wondered what allows one person to stop at one glass of wine when another person can’t stop until several bottles are empty? Scientists at the Salk Institute may have found the answer to that question.
As pervasive as alcohol is in society, it’s curious that more people don’t develop alcohol disorders. According to a 2017 National Survey on Drug Use and Health (NSDUH) in the United States, 83% of people ages 18 and older have consumed alcohol at one point in their life. Out of that, 83%, 5.7%, was reported to have an alcohol use disorder, which includes binge drinking. According to the National Institutes of Health (NIH), an alcohol use disorder is a chronic brain disease in which an individual drinks compulsively, despite adverse outcomes.
Scientists have long wondered what leads some people to drink compulsively and others to stop. Previous research had focused on the brain after binge drinking had already developed. Researchers at the Salk Institute were interested in what occurs within the brain prior to and during compulsive drinking.
Researchers Study Compulsive Drinking in Mice
Published in the November 21, 2019 issue of Science, researchers discovered a brain biomarker— a test result measurement—which predicts compulsive drinking. While studying the effects of alcohol consumption on the brain of mice, the researchers observed a brain circuit involved in the control of compulsive drinking.
The study began with a test called a binge-induced compulsion task (BICT) to test how the experience of drinking affects alcohol consumption in mice. To create an unpleasant experience, the researchers infused the alcohol with a bitter taste as a negative consequence for the BICT.
Upon testing the mice with the bitter alcohol, the researchers were able to categorize the mice into three tiers: low drinkers, high drinkers, or compulsive drinkers. The low and high drinkers reacted to the bitter alcohol by stopping their consumption. The compulsive drinkers, on the other hand, were not deterred by the bitter taste. They were not affected by the negative consequence (bitter taste).
Armed with this data, the researchers used an imaging technique to evaluate the cells and brain regions of the mice throughout the consumption processes: before consumption, during consumption, and after consumption.
They noted communication activity in the neural connection between the area of the brain involved in controlling behavior and the other area which controlled responses to negative events. They found that neural patterns between the two sections could predict which mice would be compulsive drinkers. Upon the first drink, a particular neural pattern would indicate if a mouse was going to become a compulsive drinker in the future.
Taking the study further, the researchers used a method called “optogenetics” to control the activity in the neural pathway between the two brain areas. In this way, they could either reduce or increase compulsive drinking in the mice. In other words, they could predict which rats would be compulsive drinkers through a biomarker (test). And they could also direct whether a mouse would consume compulsively or not.
The Salk Institute researchers would like to continue their studies involving the neural network biomarker in the future. Whether the biomarker is applicable only to alcohol is unknown. To find whether other substances or natural rewards have the same type of biomarker, the researchers must perform further testing, and much is yet to be discovered. Regardless, this is promising news for the area of addiction research.