IS there really a scientific link between drinking alcohol and violent behaviour? A Morgan Poll this year found that 14.5million Australians think there is, and the statistics seem to agree.

University of NSW psychologist Thomas Denson, who studies aggression and alcohol, says there is definitely a connection between alcohol and aggression.

"It's one of the most replicated effects in psychology," he adds.

But why? "Once you start drinking your attention is impaired. You are only able pay attention to the salient aspects of the situation, such as being provoked, and less likely to pay attention to things that attenuate aggression, like a security guard or police officer," Denson says.

This theory of alcohol-induced aggression is called alcohol myopia because it creates tunnel vision where you focus on the most noticeable information in front of you, which is often the most frustrating. Alcohol myopia is partly explained by how alcohol affects our brain. "Alcohol affects the prefrontal cortex. It reduces activity in this area in the short term. And in long-term alcoholics you see atrophy in this area; that is, people are actually losing neurons."

The prefrontal cortex is important in behavioural control, including inhibiting aggression. Alcohol also increases arousal as it is being absorbed into the bloodstream. "As our blood-alcohol level increases, people are more chatty and excited," Denson says. "In this state, while people are aroused and then provoked, they tend to misattribute that arousal to the provocation."

That is, people think they are angry because they have just been bumped into and not because of the effect of alcohol on their arousal. When the blood-alcohol level begins to fall, people become more sedated, and their levels of arousal and aggression drop.
Denson also studies the impact of people drinking alcohol after they have been heavily provoked during the day. "It's the situation when you have a bad day at work and your boss yells at you, you go to the bar, have a few drinks, encounter a minor provocation and become highly aggressive." He calls these studies "a laboratory model of domestic violence".

He has found that subjects who ruminate over drinks about the provocation that occurred during the day are more aggressive than subjects who are distracted and don't think about their problems when they are drinking. "It's important to take your mind off the original provocation, to allow time for the arousal to go down," Denson says.
But the effect of alcohol on our behaviour isn't all neurological. "The role of the social environment is huge," Denson says. "For instance, when people hang out in violent bars, there is more anger and violence." Alcohol provides a good excuse for people to behave badly.

Denson hopes his research will "shed some light on the psychological processes that contribute to alcohol-induced aggression. Once these processes are identified, we can attempt to intervene and reduce the harm associated with this widespread phenomenon."

Original article by Wendy Zukerman, The Australian, 29 October, 2008