The pattern of knocking back a few drinks every few days, followed by days of no drinking, can cause more brain damage in rats than drinking moderately every day, say scientists from The Scripps Research Institute in La Jolla.
And the damage caused to the prefrontal cortex sets up a cycle of craving more and more alcohol during the dry periods, so over-drinking occurs when finally given the opportunity to drink. This is, in part, the result of damage that disrupts the processes that normally inhibit reckless behavior.
“Believe me, I’m not saying people should drink every day and have unlimited access to alcohol,” said Olivier George, lead researcher on the study and senior staff scientist at Scripps. “We’re just saying that binge drinking can cause a lot of damage.”
George, a neuropharmacologist, was looking at the differences in behavior, brain function and physiology in rats exposed to unlimited amounts of alcohol and those that could drink only on Tuesdays, Thursdays and Saturdays.
He said he became interested in doing such a study because, being French, he had always wondered why alcohol dependence was so much higher in the United States and Canada than in his own country, where – on average – people drink more per year than their North American counterparts.
“The French drink about 22 liters of pure alcohol every year,” he said. “Canadians and Americans drink somewhere between 17 and 18 liters.”
It just didn’t make sense that those who drink less would have more dependency on it. So, he and his colleagues at Scripps decided to see if there was something about the behavior of drinking – the when, the how, how much at one time – that might explain it.
“When I lived in France, I’d have a glass or two of wine, every day, with food,” he said. “I moved to America. And I love happy hour. I started to drink more like an American,” he said, which means not every day.
But on the days that you do, you might drink a lot.
So, the researchers set up an experiment in which they created three groups of rats: one that didn’t drink alcohol; another that drank only on Tuesdays, Thursdays and Saturdays; and a third that had unlimited access to alcohol.
Over the next six weeks, the researchers found that those with unfettered access didn’t abuse the drink –they drank lightly. But the rats that got alcohol only on occasion would drink a lot when they got it.
“It’s like a lot of things in life that the brain perceives as good,” he said. “If it loses access to it, you feel bad. You get into a negative emotional state, say a little bit frustrated, and so you take more the next time you have access.”
The researchers then looked at the brains of the rats. They found that when the binge-drinking rats were on their dry days, the prefrontal cortex – the area of the brain that controls behavior and emotion – seemed disconnected from the areas it is supposed to regulate, such as the amygdala, whichstores emotional memory.
“We normally see such changes in the brains of humans or other animals that are highly dependent on alcohol, but here we found these changes in the rats after only a few months of intermittent alcohol use,” George said.
The bingers also scored poorly on memory tests, which indicates a malfunction in executive control. The rats who drank moderately, and every day, didn’t suffer from these problems.
“One can see the vicious cycle here,” George said. “They drink to restore normal prefrontal function, but ultimately, that leads to even greater impairment.”
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