When consumed in substantial amounts, alcohol produces changes in the brain and body that normally help deter additional drinking. However, some people don’t seem to react as strongly to the negative effects of alcohol and therefore have greater chances of continuing their consumption to excess. In a study published in April 2014 in the journal PLOS One, researchers from the University of Utah School of Medicine used laboratory experiments on rats to investigate what may happen to drinkers who lose function in a brain area responsible for recognizing some of the damaging consequences of excessive alcohol intake.
In addition to its mind-altering impact, alcohol has a toxic effect on organ systems throughout the body. For this reason, the liver works hard to break down any alcohol you consume. Unfortunately, the first part of this breakdown process produces a substance, called acetaldehyde, which also has a toxic effect on the body. A buildup of acetaldehyde in the bloodstream of a person who consumes a significant amount of alcohol helps explain the gradual or rapid appearance of unpleasant feelings that can make that person question the wisdom of continuing to drink. The onset of these unpleasant sensations also helps to deter the consumption of enough alcohol to trigger the potentially lethal condition called alcohol poisoning. In the aftermath of significant alcohol intake, drinkers also commonly experience negative consequences in the form of a group of symptoms known collectively as a hangover. Some individuals with a high sensitivity to alcohol may experience these symptoms—which include such things as muscle trembling, muscle pain, headaches, lightheadedness, nausea and vomiting—after consuming even a single drink.
Excessive Alcohol Consumption
Excessive alcohol consumption is a term used to describe any pattern of short- or long-term alcohol intake that can endanger your health or well-being. Short-term excessive intake includes binge drinking, an activity that involves consuming enough alcohol in a single drinking session to reach legal intoxication. Longer-term excessive intake generally falls under the heading of heavy drinking, which involves drinking enough alcohol on a daily or weekly basis to seriously increase your chances of eventually developing diagnosable symptoms of alcohol use disorder (which encompasses both alcohol abuse and alcoholism). Known potential consequences of binge drinking include alcohol poisoning, participation in behaviors that pose a danger to self or others, and participation in unprotected sex. In addition to alcohol use disorder, known potential consequences of ongoing heavy drinking include serious liver and cardiovascular disease and the onset of major depression or other severe mental health problems.
Brain Function Problems
In the study published in PLOS One, the University of Utah researchers used laboratory experiments on rats to determine what happens when a specific area of the brain, called the lateral habenula, does not work properly. Normally, this area of the brain increases its level of activity when a person is exposed to negative or unpleasant experiences. The researchers worked with two groups of rats; the animals in the first group had their lateral habenulas inactivated in order to simulate the presence of brain damage, while the second group experienced no such brain inactivation. For a number of weeks, the rats in both groups were periodically allowed to consume a beverage with an alcohol content somewhere between that of beer and distilled liquor. The researchers concluded that, compared to the rats unaffected by simulated damage in the lateral habenula, the rats affected by this damage increased their baseline level of alcohol intake at a faster pace and also consumed more alcohol overall.
“The way I look at it is the rewarding effects of drinking alcohol compete with the aversive effects,” explained Andrew Haack, who is co-first author on the study with Chandni Sheth, both neuroscience graduate students at the University of Utah. “When you take the aversive effects away, which is what we did when we inactivated the lateral habenula, the rewarding effects gain more purchase, and so it drives up drinking behavior.”
Significance and Considerations
The authors of the study published in PLOS One note that an escalating pace of alcohol consumption is one of the hallmarks of the switchover from non-problematic drinking behaviors to drinking behaviors that can eventually result in alcoholism. They believe that their findings help demonstrate how damage in the brain’s lateral habenula can lead to such an increase in alcohol intake. It’s important to note that no one knows precisely how this brain area helps limit drinking when it works properly. On one hand, it may help people remember the negative consequences of previous episodes of excessive alcohol consumption. On the other hand, it may actually contribute to the unpleasant sensations that can deter excessive consumption. The study’s authors believe that better understanding of this mechanism may help doctors and public health officials predict which drinkers will fall into problematic patterns of alcohol intake.