Too much alcohol can ruin a man’s appreciation of irony and block feelings of empathy. And that’s true even when he’s sober, a new study suggests.

Scientists suspect that chronic heavy drinking damages parts of the brain that are crucial to decoding others’ emotions and to processing humor, especially irony.

“Chronic alcohol abuse seems to have effects on the perception and decoding of emotional expressions,” says Simona Amenta, a post-doctoral researcher at Italy’s University of Milano-Bicocca and a lecturer at the Catholic University of Milan. “It has been associated with … deficits in emotion recognition and verbalization, leading to difficulties in distinguishing and comprehending people’s emotional states.”

Some studies, in fact, have shown that alcoholics tend to misidentify the emotions of people they are interacting with, Amenta notes. So sadness can be mistaken for anger, while happiness might come across as a negative emotion.

To look at the impact of chronic heavy drinking on emotion recognition, Amenta and her European colleagues tested 22 men who were in their third week of an alcohol detoxification program. They compared them to 22 men who were not alcoholics, the team reported in the journal Alcoholism: Clinical & Experimental Research.

All 44 study volunteers were asked to read a series of stories that concluded with either a straightforward sentence or an ironic one. They were then asked to complete a questionnaire designed to determine whether the men could understand the emotional states of the characters in each story and also detect when characters were speaking ironically.

The men would need to be sensitive to others’ emotions to be able to determine whether a character’s concluding statement was straightforward or whether it was conveying the opposite meaning -- in other words, whether it was spoken with irony.

One example of the type of story the men were asked to read was about a dinner party: “Sarah invited her coworkers over for a work dinner and asked everybody not to be late.”

Some of the men received a version of the story with a straightforward ending: “Paul is the first to arrive. Sarah says: ‘You’re right on time!’”

Others got the story with an ironic ending: “Paul arrives when the dinner has already begun. Sarah says: ‘You’re right on time!’”

As it turns out, the drinkers were much worse at detecting irony. In fact, they identified ironic sentences correctly only 63 percent of the time, as compared to 90 percent of the non-alcoholic volunteers.

What this means is that problem drinkers can completely misinterpret what they’re seeing and hearing.

Lara Ray, an assistant professor of psychology and psychiatry at the University of California, Los Angeles, isn’t surprised to see differences in how alcoholic and non-alcoholic brains work. Chronic alcohol abuse changes the brain, she says.

The kinds of misinterpretations alcoholics make might predispose them to getting into the fights that seem all too common in bars.

That, plus the fact that alcohol is a disinhibitor. “So those who are higher in aggression become more aggressive,” Ray adds.