Have you ever witnessed a friend become increasingly aggressive during a night out? As their bar tab grows, so does their aggression and hostility. They get into a silly (but heated) argument with another friend or better yet, a random person minding their business in the corner. And before you know it, they’re getting the boot for causing a scene.

Chances are, you have witnessed this before or even found yourself in a similar scenario… because alcohol tends to make us angry—but why? According to new research published in Cognitive, Affective, & Behavioral Neuroscience, the answer lies within our prefrontal cortex.

This study “The neural correlates of alcohol-related aggression” from the University of New South Wales in Australia found a link between an increase in aggression following the consumption of alcohol and a decrease in activity in the prefrontal cortex. Researchers say that after study subjects had just two drinks, there were notable changes in the prefrontal cortex of the brain, which usually helps to moderate one’s levels of aggression. Past researchers have theorized that alcohol-related aggression is a direct effect of changes in the prefrontal cortex, but they didn’t have the neuroimaging evidence to back it up. This study, on the other hand, does.

The research team enlisted 50 young, healthy men, who were instructed to drink either two vodka drinks, or two placebo drinks that didn’t contain any alcohol at all. These participants then underwent an MRI scan, while completing an aggression task, commonly used to observe and measure levels of aggression upon being provoked. The MRI gave the researchers an inside look at which areas of the brain were activated during completion of the task. Furthermore, the scans allowed them to compare differences between individuals who consumed alcohol and those who did not.

Upon assessment of the MRI scans, the researchers found that being provoked into aggression had no notable influence over an individual’s neural responses. However, when the participants began to act aggressively, there appeared to be a decrease in activity in the prefrontal cortex of those who drank the two vodka drinks. At this time, there also appeared to be an increase in areas of the brain that have to do with our reward system. Furthermore, an increase in activity was observed in the hippocampus—an area of the brain associated with memory—in these individuals.

Lead researcher Thomas Denson explains the team’s observations and subsequent conclusions, as reported by NeuroscienceNews: “Although there was an overall dampening effect of alcohol on the prefrontal cortex, even at a low dose of alcohol we observed a significant positive relationship between dorsomedial and dorsolateral prefrontal cortex activity and alcohol-related aggression. These regions may support different behaviors, such as peace versus aggression, depending on whether a person is sober or intoxicated.”

Springer (2018, February 12). Brain Scans Show Why People Get Aggressive After a Drink or Two. NeuroscienceNews. Retrieved February 12, 2018 from http://neurosciencenews.com/aggression-alcohol-8478/

Denson, T. F., Blundell, K. A., Schofield, T. P., Schira, M. M., & Kramer, U. M. (2018, January 8). The neural correlates of alcohol-related aggression. Cognitive, Affective, & Behavioral Neuroscience. Retrieved on February 21, 2018 from https://link.springer.com/article/10.3758%2Fs13415-017-0558-0