Researchers used functional MRI to monitor brain activity in 15 abstinent long-term alcoholics while they looked at images of faces with positive or negative emotional expressions. The brain scans revealed decreased activation in the amygdala and hippocampus, regions of the brain used for processing facial emotions.

The inability to judge emotional expressions "can result in miscommunication during emotionally charged situations and lead to unnecessary conflicts and difficulties in interpersonal relationships. The resulting negative repercussions can, in turn, contribute to increased drinking," study author Ksenija Marinkovic, an assistant professor in residence in the radiology department at the University of California, San Diego, said in a news release from Alcoholism: Clinical & Experimental Research, which is publishing the findings online and in its November print issue.

The study also found that the brains of the alcoholics recruited the prefrontal cortex while processing facial emotions, perhaps compensating for the reduced activation of the amygdala and hippocampus.

Previous studies found that reduced amygdala activity occurs in psychopaths and in people with a family history of alcoholism.

"Amygdala hypoactivity may underlie emotional dysfunction in chronic alcoholics ... and be part of a wide array of behavioral problems, including disinhibition and disregard for social norms," Marinkovic said.

"Viewed in their totality, these results show that not all facial expressions are necessarily perceived the same by everyone, and that alcoholics may be at a special disadvantage in detecting emotion-filled facial expression, which we all naturally use to convey information, such as warnings, love, anger and defense, among others, and assume that the intended message is accurately perceived," Edith V. Sullivan, professor in the department of psychiatry and behavioral sciences at Stanford University School of Medicine, said in a news release.

"Whether the differences between controls and alcoholics in brain activation existed before the onset of alcoholism, or are the result of neural circuitry changes or differences in blood perfusion caused by chronic alcohol consumption, intoxication or withdrawal, remain as questions to be answered," Sullivan said.

More information

The U.S. National Institute on Alcohol Abuse and Alcoholism has more about alcoholism.