How heavy alcohol consumption increases brain inflammation

For people with alcohol use disorder (AUD), there is a constant, vicious cycle between changes to the brain and changes to behavior. Alcohol use disorder can alter signaling pathways in the brain; in turn, those changes can exacerbate drinking.

Now, scientists at Scripps Research have uncovered new details about the immune system’s role in this cycle. They reported in the journal Brain, Behavior and Immunity, that the immune signaling molecule interleukin 1β is present at higher levels in the brains of mice with alcohol dependence. In addition, this interleukin pathway takes on a different role in these animals, causing inflammation in critical areas of the brain known to be involved in decision-making.

In the new study, researchers compared alcohol-dependent mice with animals drinking moderate or no alcohol at all. They discovered that the alcohol-dependent group had about twice as much IL-1β in the medial prefrontal cortex, a part of the brain that plays a role in regulating emotions and behaviors.

The team then went on to show that IL-1β signaling in the alcohol-dependent group was not only increased, but also fundamentally different. In mice that had not been exposed to alcohol, as well as in mice that had drunk moderate amounts of alcohol, IL-1β activated an anti-inflammatory signaling pathway. In turn, this lowered levels of the inhibitory neurotransmitter gamma-aminobutyric acid, a signaling molecule known to regulate neural activity in the brain.

Reference:

How heavy alcohol consumption increases brain inflammation, Brain Behavior and Immunity, DOI: 10.1016/j.bbi.2023.02.020