Wednesday, October 3, 2012

Alcohol Consumption Affects Ability To Overcome Fear

Doctors have known for a long time that alcoholism is associated with increased risk of anxiety, such as PTSD (post traumatic stress disorder), and that heavy drinkers are more likely to be involved in automobile accidents and/or domestic violence situations.

Now, new research by experts at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and UNC's Bowles Center for Alcohol Studies, published online September 2, 2012 in Nature Neuroscience has determined that high alcohol consumption rewires brain circuitry, which suggests that it is more difficult for people who drink heavily to bounce back from a traumatic event in their lives. 

Thomas Kash, PhD, assistant professor of pharmacology at the University of North Carolina School of Medicine commented: "There's a whole spectrum to how people react to a traumatic event. It's the recovery that we're looking at - the ability to say 'this is not dangerous anymore.' Basically, our research shows that chronic exposure to alcohol can cause a deficit with regard to how our cognitive brain centers control our emotional brain centers."

For their trial, the experts split mice into two groups. The first was given the equivalent amount of alcohol for humans that is twice the limit allowed for driving. The second was not given any alcohol at all. The mice were then taught by use of small shocks to be scared of a certain sound the researchers played. 


The researchers observed that when the sound played over and over without the shock, the mice who were in the no alcohol group eventually stopped being scared of the tone. On the other hand, the mice who had high exposure to alcohol were scared of the noise, making them stand completely motionless every time they heard it - for a long time after the shocks were not present.

The authors explain that these findings are very much like the ones seen in individuals who suffer from PTSD, with these people taking longer to get over a certain fear even when the situation is not one that they should be scared of anymore. 

They believe that this evidence stems back to the neural circuitry of the mice that were chronically exposed to alcohol. When analyzing the brains of the two different groups of mice, the researchers found that the nerve cells found in the prefrontal cortex of the brains of the mice who had been exposed to alcohol, were shaped differently than the mice who had not been exposed to any alcohol. They also noticed that NMDA, an important receptor in the brain was not as active in the mice who consumed alcohol.

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