The brain's reward system appears to perpetuate binge drinking.
The National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines binge drinking as "a pattern of drinking that brings a person's blood alcohol concentration to 0.08 grams percent or above."
In an adult, this is typically equivalent to five or more drinks for men, or four or more drinks for women, within the space of 2 hours, but people with a lower body weight will reach this level earlier.
Moderate drinking, on the other hand, is defined as up to one drink per day for women and two for men, according to the Dietary Guidelines for Americans.
The Centers for Disease Control and Prevention (CDC) state that around 1 in 6 adults binge drink about four times each month, and 70 percent of binge drinking is done by people over 25 years of age, with over-65s indulging more frequently.
Amygdala and ventral tegmental area keep the loop going
Previous studies have suggested that the extended amygdala and the ventral tegmental areas (VTA) of the brain play a role in alcohol binge drinking.
- The CDC note that binge drinkers are 14 times more likely to drive under the influence than non-binge drinkers
- People earning over $75,000 tend to binge drink more than those on lower incomes
- Over 50 percent of alcohol consumed in the U.S. is through binge drinking.
In experiments on mice, Todd Thiele and colleagues, from the University of North Carolina at Chapel Hill, identified a functional circuit linking these areas that appears to explain why people binge drink.
The team found that alcohol puts stress on the cells in the extended amygdala. These cells then release corticotropin releasing factor (CRF). Through connections called long projection neurons, CRF then acts on the VTA. The VTA produces a sense of reward.
In other words, drinking alcohol starts up a loop in which the more a person consumes, the greater the reward experienced by the brain.
This encourages the person to keep drinking.
Alcohol is known as a psychostressor.
The VTA responds to the rewarding properties of food and drugs of abuse, including alcohol.
Together, they form a functional circuit that controls binge drinking.
The authors suggest that inhibiting a circuit between these two brain regions of stress and reward can inhibit binge alcohol drinking.
They believe that manipulating the CRF system could provide a treatment option for people with a problem of binge drinking.
While the CDC note that binge drinkers are not generally alcohol-dependent, the researchers say that the new insights could lead to the development of pharmacological treatments that might help prevent dependence from forming.
"It's very important that we continue to try to identify alternative targets for treating alcohol use disorders. If you can stop somebody from binge drinking, you might prevent them from ultimately becoming alcoholics.
We know that people who binge drink, especially in their teenage years, are much more likely to become alcoholic-dependent later in life."