Heavy drinking doesn’t just harm your health in the short term—it can leave lasting damage in your brain that affects how you think and make decisions.
For the first time, researchers have shown in an animal study how chronic alcohol use causes long-term problems in the brain’s decision-making circuits.
Scientists at Johns Hopkins University found that rats exposed to large amounts of alcohol had trouble making decisions even months after they stopped drinking. Compared to healthy rats, their brains looked and worked very differently.
This study, published in Science Advances, gives us a new explanation for how alcohol changes the brain in a way that leads to poor choices, even after the drinking has stopped.
Patricia Janak, a neuroscientist at Johns Hopkins who led the study, explained that people with alcohol use disorder often have problems with learning and decision-making. These difficulties can lead to a cycle of poor decisions, like going back to drinking.
The goal of this research was to understand what’s happening in the brain when someone struggles with decision-making after alcohol abuse. “We needed an animal model to better understand how chronic alcohol abuse affects the brain,” she said.
In this study, rats were given very high doses of alcohol for a month. After a break of almost three months to let the alcohol leave their systems, the rats were tested using a difficult decision-making task. In the test, each rat had to choose between two levers to get a reward.
One lever had a higher chance of giving a reward, but every few minutes, the “winning” lever would switch. So the rats had to constantly watch for the changes and adjust their behavior to get the most rewards.
The rats that hadn’t had alcohol learned the task well. They quickly figured out when the winning lever had changed and made better decisions. But the rats that had been exposed to alcohol had a much harder time adjusting. They made slower and less accurate decisions.
The scientists believe that earlier studies failed to show this difference because those experiments used easier tasks that didn’t really challenge the brain’s decision-making ability.
“Our experiment was quite challenging and the alcohol-exposed rats just couldn’t do it as well,” Janak explained. “The control rats were more strategic and showed stronger brain signals related to making decisions.”
The research team discovered that the alcohol had harmed a specific part of the brain called the dorsomedial striatum. This area is important for making decisions and adjusting behavior when things change. In the alcohol-exposed rats, this region had changed so much that it couldn’t process information effectively anymore.
What shocked the scientists most was how long the effects lasted. Even after nearly three months without alcohol, the rats still had trouble thinking clearly. This might help explain why many people relapse after going through rehab. If alcohol damages the brain’s ability to make good choices, it may be harder to stay sober.
Interestingly, the scientists only found these effects in male rats. That doesn’t mean females aren’t affected, but it may mean that alcohol impacts male and female brains differently. The team plans to study this further, along with how alcohol affects other connected brain regions.
This research adds to what we know about how dangerous heavy drinking can be—not just while someone is drinking, but long after they stop. Understanding these brain changes may lead to better ways to help people recover from alcohol addiction and avoid relapse.
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The study is published in Science Advances.
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