In a groundbreaking new study, researchers have shown for the first time in animals how long-term heavy alcohol use leads to lasting damage in brain circuits tied to decision-making. The findings help explain why people with alcohol use disorder (AUD) often struggle with making good choices—even after long periods of sobriety.
The research, published today in Science Advances, was led by scientists at Johns Hopkins University. It shows that rats exposed to large amounts of alcohol for a month continued to perform poorly on a memory and strategy task even after being alcohol-free for nearly three months.
Brain scans revealed major changes in the way their brains processed decisions compared to healthy rats.
“This gives us a new model to understand what happens in the brains of people with alcohol use disorder,” said senior author Patricia Janak, a neuroscientist who studies addiction. “We know that people with alcohol addiction often make poor choices. Now we can see similar behavior in animals and link it directly to specific brain changes.”
To test this, Janak’s team, led by research scientist Yifeng Cheng, gave rats very high doses of alcohol over a month—similar to levels seen in chronic heavy drinkers. After a long withdrawal period of nearly three months (equal to years in human terms), they tested the rats using a difficult reward-based task.
In this task, the rats had to choose between two levers. One lever had a higher chance of giving a reward—but every few minutes, the better lever switched. Rats needed to quickly adapt their choices to keep getting the reward.
Healthy rats were able to detect the change and adjust their behavior. But the alcohol-exposed rats were slower, less flexible, and made worse decisions.
The task was designed to be more complex than previous animal experiments, which may have been too easy to show real effects of alcohol on thinking. “This test required memory, learning, and quick adjustment—much like the decisions people face in everyday life,” said Janak. “And the alcohol-exposed rats just couldn’t keep up.”
The poor performance was linked to changes in a key part of the brain called the dorsomedial striatum, which helps control decision-making and flexible thinking. Brain recordings showed that alcohol-exposed rats had weaker signals in this area, suggesting that alcohol had damaged the neural circuits that help process changing information and make good choices.
One of the most surprising results was how long these brain changes lasted. Even after the rats had been sober for months, the decision-making problems and brain damage remained. “This may help explain why relapse is so common, even after rehab,” said Janak.
“The brain doesn’t just bounce back. These long-term changes may make it harder for people to stay sober because their ability to make healthy decisions is impaired.”
Interestingly, the deficits were found only in male rats in this study. The team doesn’t believe this means female rats—or women—are protected from alcohol’s effects, but rather that sex differences in brain biology may change how alcohol affects thinking over time. The researchers plan to investigate this further.
Next, the team hopes to study other brain regions that interact with the dorsomedial striatum and to explore what causes the differences between male and female brains after alcohol exposure.
This research adds critical knowledge to the understanding of alcohol addiction. It shows that the damage from alcohol doesn’t end with sobriety—the brain may still be struggling long after a person has stopped drinking. Understanding these changes may one day help in designing better treatments to improve decision-making and prevent relapse.
If you care about wellness, please read studies about how alcohol affects liver health and disease progression, and even one drink a day could still harm blood pressure health.
For more health information, please see studies that your age may decide whether alcohol is good or bad for you, and people over 40 need to prevent dangerous alcohol/drug interactions.
The research findings can be found in Science Advances.
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