Medical University of South Carolina researchers, funded by the National Institutes of Health, have found that the deactivation of a stress-signaling area of the brain associated with emotion-related and motivational behaviors can decrease binge drinking.
The study, which will appear in the May issue of Neuropharmacology and was published online in February, was led by Howard C. Becker, Ph.D., director of the Charleston Alcohol Research Center and professor in the Department of Psychiatry and Behavioral Sciences.
The National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines binge drinking as "a pattern of drinking that brings blood alcohol concentration (BAC) levels to 0.08g/dL (the legal limit)" within 2 hours. This usually occurs at 5 drinks for men or 4 drinks for women.
According to Becker, "Binge drinking is one of the most common patterns in which alcohol is consumed... one consequence of repeated binge drinking is increasing the risk for developing an alcohol use disorder (AUD)." Becker adds that consistent binge drinking, especially during the adolescent and college years, puts those who binge at nearly 10 times the risk for developing an AUD.
First author of the study and graduate student in the Becker laboratory, JR Haun explained what the NIAAA acknowledges as 'standard' for specific beverage types. "A drink is defined as roughly one 12-ounce can of beer, a 5-ounce glass of wine or a standard 1.5 ounce shot of distilled spirits." However, he added that the serving size can vary, depending on the percentage of pure alcohol in the drink.
The Strategy Tested
The potential strategy Becker and Haun tested for curbing binge drinking involved manipulating a brain system called the opioid receptor system that is well-known in the addiction field. Opioids such as oxycontin, oxycodone, morphine, and heroin act on this brain system to produce pleasurable effects. This is what puts users of these drugs at such a high risk of developing an addiction.
However, there is one opioid receptor that is the odd one out—the kappa opioid receptor system, which is also referred to as an anti-reward system. This system produces feelings of discontent and stress, as opposed to feelings of pleasure.
The positive effects that people feel when they drink are partially due to opioid receptors being stimulated. Once they've finished drinking, however, and the stress of withdrawal symptoms kick in, this activates the kappa opioid receptor system.
To test their strategy, the research team honed in on a structural network in the brain known as the extended amygdala in mice. This is a region of the brain involved in motivational behavior and is highly responsive to stress, as well as associated with compulsive drinking. This network contains several kappa opioid receptors. Hence, it was an obvious candidate for investigating the role it has in curbing excessive drinking.
This binge-drinking mouse model permitted the mice to drink as much as they wanted for 4 hours every night. According to Becker, "The mice will drink enough alcohol in this relatively short period of time to achieve blood alcohol levels that would define it as a binge episode."
By deactivating the kappa opioid receptors in the mice with a drug, binge drinking was decreased. This discovery points to the important role the kappa opioid receptor system plays in not only the negative effects of withdrawal but also the motivation to binge drink as well.
These findings can easily sound counterintuitive. How could turning-off the negative effects of this system of the brain decrease drinking? According to Haun, the answer to this question is not entirely clear.
"But what we do know is that kappa opioid receptors play an important role in the negative emotional state that drives drinking when it becomes compulsive in alcohol use disorders," Haun said.
Haun and Becker hypothesize that the kappa opioid receptor system may drive binge drinking and compulsive alcohol use similarly, as well as contributing to uneasiness and stress in the state of withdrawal. The finding also backs up Becker and Haun's hypothesis that the kappa opioid receptor system in the extended amygdala motivates binge drinking.
So is a pill to curb binge drinking in our future?
Becker suggests this type of therapy, if developed, would be most appropriate for those who struggle with controlling chronic drinking, like those with an AUD or those who are at an elevated risk of developing one.
Although such therapeutics may be developed, nothing can replace recognizing destructive behaviors and trying to reverse them by reversing the negative thinking that drives them. A pill may help curb binge and chronic drinking, but probably not without the support of counseling, behavioral therapy, replacing negative behaviors with healthy ones, and improved self-care.