Drunken bar fights, unfortunately, have a very long history. Verbal insults, often leading to acts of physical aggression or unwanted physical contact, can lead to serious physical violence and casualties. Why do people get aggressive after drinking?
In a study led by Thomas Denson of the University of New South Wales in Australia, in the journal ‘Cognitive, Affective, & Behavioral Neuroscience’ which is an official journal of the Psychonomic Society and is published by Springer, researchers used magnetic resonance imaging (MRI) scans that measure blood flow in the brain to better understand why people often become aggressive and violent after drinking alcohol. After only two drinks, the researchers noted changes in the working of the prefrontal cortex of the brain, the part normally involved in tempering a person’s levels of aggression.
According to most theories, alcohol-related aggression is caused by changes in the prefrontal cortex. However, there is a lack of substantial neuroimaging evidence to substantiate these ideas. In this study, the research teams recruited 50 healthy young men who were either given two drinks containing vodka, or placebo drinks without any alcohol. While lying in an MRI scanner, the participants then had to compete in a task, which has regularly been used over the past 50 years to observe levels of aggression in response to provocation.
The MRI allowed the researchers to see which areas of the brain were triggered when the task was performed. They could also compare the difference in scans between participants who had consumed alcohol and those who hadn’t. Being provoked was found to have no influence on participants’ neural responses. However, when behaving aggressively, there was a dip in activity in the prefrontal cortex of the brains of those who had consumed alcoholic drinks. This dampening effect was also seen in the areas of the brain that are involved in reward. Also, heightened activity was noted in the hippocampus, the part of the brain associated with people’s memory.
“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,” explains Denson. “These regions may support different behaviours, such as peace versus aggression, depending on whether a person is sober or intoxicated.”
An earlier study in 2013, by a team of researchers led by Penn State sociologists, found that in one-third of barroom brawls bystanders stepped in non-aggressively. About 72% fights were broken like this. Most of those that jumped in were male, and they were more likely to step in when both participants in the fight were also male. The researchers noted, “Aggression in bars is largely a male phenomenon, with bars being settings with heightened concerns regarding male honour and identity.”