09/17/2009 05:12 am ET Updated Nov 17, 2011

Sad? Angry? Happy? Alcoholics May Not Know What Your Face Is Saying

Of the many things that long-term alcohol addiction can steal -- careers, lives, health, memory -- one of its most heartbreaking tolls is on relationships. Alcoholics, researchers have long known, have a tendency to misread emotional cues, sometimes taking offense when none was intended or failing to pick up on a loved one's sadness, joy, anger or disappointment.

The misunderstandings can result in more drinking, and more deterioration of relationships and lives.

How does alcohol do all that? A new study finds that the brains of long-term alcoholics, even those who have long abstained, often differ from nonalcoholics' in ways that make them poorer judges of facial expressions. In particular, alcoholics register less intensity in the amygdala and hippocampus (collectively known as the limbic system) when observing faces.