Alcohol Alters Brain Function, NIH Study Finds

Alcohol addiction doesn't just affect certain brain regions but can lead to dramatic changes in the entire brain, a new study from the National Institutes of Health says.

Researchers found that long-time alcohol exposure can lead to a shift in brain behavior from an area that makes decision to an area that controls habits. The study shows that changes in brain functioning are the reason behind alcohol being such an addictive and behavior changing substance.

People who develop alcohol dependence continue drinking alcohol even after the habit impacts their physical and mental health and disrupts relationships. Previous research has shown that people dependent on alcohol have difficulty controlling impulses and solving problems that require prefrontal cortex. These people, however, have greater brain activity in the dorsal striatum.

The prefrontal cortex is involved in personality expression, social behavior and complex decision making while dorsal striatum is associated with reward system of the brain.

In the study, researchers looked at brains of mice that were exposed to alcohol for a very long time. The research team led by led by Andrew Holmes, Ph.D., in the Laboratory of Laboratory of Behavioral and Genomic Neuroscience at NIAAA, found that new nerves had formed in the dorsal striatum.

The changes associated with chronic alcohol exposure are similar to changes seen in brains exposed to drugs such as amphetamine. Also, alcohol inhibits functions of certain receptors that control mood and behavior.

"These findings give important insight into how excessive drinking affects learning and behavioral control at the neural level. The shift to increased striatal control over behavior may be a critical step in the progression of alcoholism," said Kenneth R. Warren, Ph.D., acting director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA).

Researchers said that treatments for alcohol addiction should focus on normalizing the functioning of striatum.

Researchers also found that mice that were exposed to high levels of alcohol had improved on some learning tasks .

"Improved performance on learning tasks that we know depend on the dorsolateral striatum is particularly interesting because it suggests that alcohol could prime the brain to favor other dorsal striatal behaviors - including things like habit formation, which may foster addictive patterns of behavior," said Dr. Holmes in a news release.

The study is published in the journal Proceedings of the National Academy of Sciences.