Threatening Social Cues: Why Alcohol Makes Us Less Responsive

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When a person is intoxicated, his or her response to others in social situations alters.

This is partly because individuals who drink excess alcohol lose their ability to properly process and respond to nonverbal messages of other people, and researchers are discovering why.

Scientists earlier realized that alcohol puts a damper on activity in the brain’s amygdala, a structure that is key in deciphering social cues found in facial expressions. Scientists also know that our brain’s prefrontal cortex is where cognition and behavior modulation is regulated.

So, researchers at the University of Illinois, Chicago College of Medicine, began wondering if intoxication affected the lines of communication between the prefrontal cortex and the amygdala, and decided to check it out.

What Was Discovered

The UIC research revealed that alcohol reduces the coupling between the prefrontal cortex area for socio-emotional information-processing and decision-making, and the amygdala. This means the social cue reader (amygdala) and the thinker and decision maker (prefrontal cortex) are not sharing information.

The researchers also noticed that alcohol intoxication made individuals much less responsive to threatening cues such as angry or fearful faces. “This suggests that during acute alcohol intoxication, emotional cues that signal threat are not being processed in the brain normally because the amygdala is not responding as it should be,” said K. Luan Phan, UIC professor of psychiatry.

The Study

The study subjects included 12 heavy social drinkers - ten men, and two women. The average age was 23. As a group, they averaged 7.8 binge-drinking episodes each month: four or more drinks per episode for the women, five or more for the men.

Participants were given either a beverage with high alcohol content or a placebo, and then underwent MRI scans as they tried to match photographs of angry, fearful, happy or neutral faces with other photos of similar expression. Alcohol impaired their ability to read facial cues and make the correct matches.

“The amygdala and the prefrontal cortex have a dynamic, interactive relationship," Phan concluded. "How the amygdala and prefrontal cortex interact enables us to accurately appriase our environment and modulate our reactions to it. If these two areas are uncouple, as they are during acute alcohol intonxication, then our ability to assess and appropriately respond to the non-verbal message conveyed on the faces of others may be impaired.”

Source: Science Daily

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