Most people use facial expressions to show and read emotions.
New research shows alcoholism can make it harder for people to understand facial expressions.
Experts say the problem can last for months after quitting drinking.
A group of researchers from the US and Belgium studied the problem in patients at an extended stay treatment center.
Even after 3 months without a drop of alcohol, the patients had difficulty reading other people's facial expressions.
Researchers say this shows chronic alcoholism is linked with neurological damage, in areas of the brain that help people communicate emotions.