How Chronic Alcohol Use Impacts the Amygdala

The amygdala is a part of the brain that plays a vital role for our emotions, our memory, and drives our “fight or flight” response. The amygdala also seems to be strongly related to the emotional response to pain, as well as positive emotions and aggression. When a person’s amygdala is damaged or destroyed, the person tends to exhibit no fear, little to no sense of personal space, and trouble remembering emotional stories. There are a variety of psychiatric disorders that cause dysfunction in the amygdala, but looking at substance use disorders, alcohol use tends to cause the greatest dysfunction of the amygdala. What exactly does chronic alcohol use do to the amygdala though? Marisa Roberto at Scripps Research Institue posed this question and found some promising results that may help combat alcohol use disorder. 

The researchers found that chronic alcohol exposure compromised brain immune cells, which is key in maintaining healthy neurons. The study at Roberto’s lab looked at a specific immune protein called Interleukin 10 (IL-10). IL-10 is linked to anti-inflammatory properties. Anti-inflammatory properties make sure that the immune system does not react too much to diseases. For the brain, IL-10 makes sure that the brain does not inflam too much to disease or injuries, now it has also been linked to chronic alcohol use disorder. In those with this disorder, IL-10 was reduced in the amygdala and did not properly signal neurons causing a higher alcohol intake. Chronic alcohol use also seems to change the brain's immune landscape. On an overall basis in the brain there were more microglia and T-regulatory cells which both produce IL-10. In the amygdala, though, IL-10 levels were lower and compromised which suggests that the amygdala responds to chronic alcohol use differently.        

Roberto’s Lab has also found that chronic alcohol use disorder affects the GABAergic and glutamatergic systems. They have found that by taking an anti-epileptic drug gabapentin it can reverse several behavioral aspects of alcohol dependence. Different labs have also linked the rise of anxiety in alcohol use patients to the amygdala due to the fact that it plays a crucial role in anxiety. Those with alcohol dependancy, and those who have an extensive family history of alcoholism show a reduced amygdala volume which predicts alcohol cravings, this may also result in disinhibition of downstream brain regions. As said before the chronic use of alcohol affects GABAergic transmission in the amygdala. Alcohol  increases presynaptic GABA release. By releasing too much GABA it means that there is not enough brain activity and can cause anxiety, hypersomnia, and daytime sleepiness. Alcohol obviously affects the amygdala in a variety of ways. There is still the question of what role chronic alcohol use plays on the amygdala and though we may be able to answer it we still do not know the full picture. 

As more studies start to come out hopefully we will be able to understand chronic alcohol use disorder more and thus provide therapies that could help those affected by it. These studies, and many others like it, are crucial in understanding addictions on a physiological level. 

Sources: https://www.sciencedaily.com/releases/2020/11/201116132248.htm 

https://www.scripps.edu/faculty/roberto/

https://www.sciencedirect.com/science/article/pii/S0006322314007070

Sara Dunn (2)