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, 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 been abstinent for long periods, are often different from those who do not suffer the affliction -- different in ways that make them poorer judges of others' facial expressions. In particular, the parts of our brains that are typically activated when we observe, record and react to expressions on another person's face -- the amygdala and hippocampus, collectively known as the limbic system -- do not respond with the same intensity in alcoholics when they observe another person's face.
The study's authors observed those differences by watching the brains of 15 abstinent alcoholics and 15 non-alcoholics at work while the subjects looked at pictures of faces expressing positive, negative and neutral emotions and answered an unrelated question ("How intelligent do you think this person is?"). As they did so, researchers from Massachusetts General Hospital and Boston University peered into their brains using functional Magnetic Resonance Imaging, which tracks brain activity from second to second. The result is published online in the journal Alcoholism: Clinical and Experimental Research.
When looking at faces that projected emotions, the amygdala and hippocampal regions of the non-alcoholics showed evidence of strong activity. When those same subjects looked at neutral facial expressions, the non-alcoholics' limbic systems were relatively quiet.
But the alcoholics' limbic systems, on the whole, responded no differently to facial expressions that conveyed strong emotion than to those that were neutral. The individuals in the two groups were matched on factors such as age, IQ, education and socioeconomic status. But their brains reacted completely differently when their eyes were confronted with evidence of anger, joy, sadness or disappointment.
At the same time, the study found some evidence of the brain's vaunted resilience and flexibility. For the abstinent alcoholics, lower levels of activity in the limbic system generally came with higher levels of activity in the frontal cortex -- the seat of judgment where cooler assessments are made. That finding is in line with a lot of research that finds that even after alcoholism has wreaked havoc on a person's brain, a lengthy period of abstinence often brings some cognitive recovery, as the brain "rewires" itself to compensate for damaged functions.
Ksenija Marinkovic, one of the study 's authors, cautioned that the study leaves one of researchers' most burning questions unanswered: Whether the blunted emotional sensitivity evident in the alcoholics came first -- and then gave way to alcoholism -- or whether alcoholism brought about changes in the brain that blunted peoples' sensitivity to others' emotions.
The idea that alcohol abuse damages the brain makes intuitive sense. But some research suggests instead that a child's cognitive deficits -- especially in the realm of emotional intelligence -- may set off a cascade of events leading to alcoholism later. Past research has shown that the children of alcoholics often exhibit the same deficits in reading emotions -- and that children of alcoholics are at far greater risk of becoming alcoholics themselves. That would suggest that emotional difficulties and miscommunications can lead to feelings of failure and discouragement, which can lead to alcohol use and eventual dependence.
"It's a chicken-or-egg problem. We just don't know which comes first," said Marinkovic, who has since moved to UC San Diego.
Wonder whether you're at risk of alcoholism and its effects, or whether your drinking could be impairing your relationships? The National Institute on Alcohol Abuse and Alcoholism has a new user-friendly website, Rethinking Drinking, where you can find out more.
-- Melissa Healy