In new rat studies, scientists have found grim evidence of just how badly alcohol impairs cognition — even after sobering up months prior.
According to new, federally-funded research out of Johns Hopkins, the decision-making parts of the brain appear, even after months of sobriety, to be highly impacted by large amounts of alcohol.
As detailed in a new paper published in the journal Science Advances, Hopkins neuroscientist and addiction researcher Patricia Janak and her students first exposed a cohort of rats to very high quantities of alcohol vapor, followed by a nearly three-month-long period of withdrawal.
After drying out, the rats that were given the booze vapor — along with a control group that had abstained — were subjected to a "reward-based decision-making test." The test involved pressing one of two levers to get a water droplet with some sugar in it — a simple task that rats learned how to do quickly to get their sweet treat. To complicate the game, however, the researchers would switch reward levers every few minutes, prompting the rats to figure out the timing of switches to get the reward.
"It was a difficult task that required memory and strategy," noted a statement about the research. "The alcohol-exposed rats performed considerably worse."
The researchers contend that their results are the first of their kind because prior alcohol studies that used animals did not "demonstrate deficits in rapid decision-making" the way theirs did. This was likely due to the decision-making tests being too easy, the scientists claimed.
"Our experiment was quite challenging, and the alcohol-exposed rats just couldn't do it as well," Janak, the paper's first author, said in the Hopkins statement. "When the right answer was constantly changing, the control rats made the best decisions faster. They were more strategic. And when we looked at their brains, the control rats' decision-related neural signals were stronger."
The research team linked the alcohol-exposed rats' difficulties with the tests to "dramatic" changes in the dorsomedial striatum, a part of the brain that governs motor function and behavioral decision-making. A known center for reward and expectations, the dorsomedial striatum has long been associated with addictive and compulsive behaviors — but this study seems to be the first to ever show just how much the neural circuits had been damaged by booze.
Notably, the researchers indicated that they were surprised that the brain damage from alcohol lasted so long, which "may give us insight into why relapse rates for people addicted to alcohol are so high," Janak said.
"Alcohol-induced neural deficits may contribute to decisions to drink even after going to rehab," the neuroscientist said. "We can clearly demonstrate these deficits can be long-lasting."
Intriguingly, the cognitive effects were only present in the male rats that were studied and not their female counterparts. While there's no reason to believe females aren't subject to alcohol-related brain damage, this finding suggests, per the Hopkins press release, that there "could be sex-related sensitivities in long-term alcohol effects on brain function."
Overall, it does seem kind of cruel to get rats so plastered that they suffer brain damage — especially when there are plenty of human alcoholics out there who would be willing to be studied. Still, these findings could be helpful in future addiction studies, and are fascinating to boot.
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