Neurological clues to how alcoholics process emotion

Alcoholics’ brains may process emotion differently than those of people who don’t have a history of alcohol abuse, according to a study published in the November issue of the journal Alcoholism: Clinical and Experimental Research. There is ample research analyzing how alcoholics tend to process emotion distinctly and with a range of behaviors—often misinterpreting nonverbal cues expressed in people’s faces, having dampened or flat reactions where others would have strong responses, being prone to impulsivity and a lack of social inhibition, and tending toward aggression, to name some. Yet, understanding the brain processes and regions that drive those behavioral differences is very much a work in progress. For most people, emotions cause the amygdala—the almond-shaped epicenter of emotional processing located deep in the brain—to light up on neuroscientists’ brain scans. But this small study of 15 now abstinent long-term alcoholics compared with 15 control participants with nearly identical backgrounds and characteristics (apart from family histories of alcoholism), reveals just how differently alcoholics process emotion.

In the study, conducted at Massachusetts General Hospital, all 30 participants were shown pictures of people’s faces expressing either happiness, sadness or no emotion. Yet instead of asking what emotion they saw, in one series of exercises researchers asked them to determine whether the faces looked intelligent; in another, they were asked simply to say whether the photos were in color or black and white. The goal was to see if there were any major differences between the alcoholics and the control group in how more complex processing (making a judgment about intellect), might compare with simple, straightforward tasks. While the alcoholics were more likely to deem the emotionless faces intelligent, and to take slightly longer when assessing intellect, “there were not major differences in their performance,” says Ksenija Marinkovic, the study’s lead author and a neuroscientist at the University of California.

Yet, when Marinkovic and her colleagues analyzed where in the brain the participants processed the facial expressions as they answered questions, a dramatic difference was quickly evident. “The healthy controls’ [brains] were activated by emotional facial expressions as one would predict in the amygdala,” she explains. Among the alcoholics, however, there was very little activity in the same region. “It was blunted.” Instead, in the group with a history of alcohol abuse, the prefrontal cortex showed increased activity, suggesting it may be compensating for the decreased emotional processing in the amygdala.

The findings go some way to understanding how, neurologically, alcoholics perceive emotions differently, and possibly help shed light on what drives the dangerous behaviors often characteristic of alcohol abuse. “You can imagine a situation, a bar perhaps, where a person who is a long term alcoholic and is under acute intoxication, would have this deficit in understanding what the other person is saying, and the emotional, facial, nonverbal cues this person is sending and would misinterpret them,” Marinkovic says.

Marinkovic’s research may also open the door for further investigation into how alcoholism impacts emotional processing, and even the genetic component of the disease. Previous research has shown, she says, that people who have a family history of alcoholism but do not suffer from the disease themselves, tended to have less activity in the amygdala when facing emotional stimuli compared with control participants. It could be, that instead of resulting from long term alcohol abuse, the dampened activity in the amygdala comes before the disease. “These results would suggest that amygdala hypoactivity, and the emotional dysfunction, may precede alcohol abuse and may be a part of the wider array of social problems,” Marinkovic says. “It may be a vicious cycle.”