Alcohol consumption is a normal part of culture for many: The National Institute on Alcohol Abuse and Alcoholism reports more than 55 percent of adults over 18 say they have had an alcoholic drink in the past month. It’s often a social lubricant and a mainstay at holiday gatherings and other important events. Low-to-moderate alcohol consumption is probably not that harmful to most people. The psychological benefits that come with the occasional drink with friends might just be good for our health. However, an estimated 1 in 6 people in the U.S. admit to regularly binge drinking—having four to five alcoholic drinks within two hours. Repeat bingers report having over 460 binge drinks per year, according to the Centers for Disease Control and Prevention. Unlike enjoying the occasional cocktail, binge drinking—and chronic heavy drinking—can be harmful to our health.
Heavy alcohol consumption can cause hepatic steatosis, or fatty liver disease. More than 90 percent of heavy drinkers develop the condition. A fatty liver can lead to other chronic diseases such as fibrosis (hardening) and cirrhosis (scarring) of the liver. Medical professionals know that alcohol may lead to fatty liver disease by causing problems with metabolism and promoting growth of new fat cells in the liver. A less-explored area is how—or if—binge-drinking behavior promotes fatty liver and whether the effects are controlled in part by the brain.
A mouse study published in the American Journal of Physiology—Endocrinology and Metabolism looked at two molecules: adenosine, a chemical that’s released when we break down a molecule called ATP that supplies the cells with energy, and a protein-like compound known as agouti-related protein (AgRP). Nerve cells in the brain use AgRP to communicate with each other.
When mice were given alcoholic beverages in a pattern similar to binge drinking, researchers found—not surprisingly—that heavy alcohol consumption leads to fat accumulation in the liver. However, they also found that the mice that did not have AgRP had less liver fat after binge drinking.
The researchers then “turned off” the mice’s sympathetic nervous system—the part of the nervous system that controls our heart rate and blood pressure. Without a functioning sympathetic nervous system, binge drinking had no influence on liver fat content either.
This research tells us that alcohol might do more than just make us a little tipsy. It seems that when the alcohol-impaired brain is in communication with the liver, it also produces metabolic effects, which lead to a buildup of fat in the liver.
Studies like this help increase awareness about the complex integration of our nervous system, metabolism and health. Having “a few too many” may not just be bad for your brain; overindulging may affect other parts of your body, too.
Brady Holmer is a PhD student in exercise physiology at the University of Florida. His lab focuses on cardiovascular physiology; mainly how exercise can play a role in health, disease and aging.