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Scientists Try to Assess the Impact of Binge Drinking on the Brains of Teens - 2
email this pageprint this pageemail usLaura Hambleton - Washington Post
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December 07, 2010

Darkened areas highlight where binge drinking adolescents had altered white matter on the brain from the control group. (Susan Tapert)
In humans that is called blackout drinking; in rats Swartzwelder calls it a profound memory deficit. It works like this: A teen drinks heavily but continues to function and doesn't lose consciousness. But the next day he or she cannot remember a thing that happened. The hippocampus stopped encoding new memories during that blackout time, according to Swartzwelder.

Swartzwelder gives his rats a dose of alcohol, and then "we teach them to go through the maze. And then see how they do."

Not very well, apparently, which probably has implications for humans. If a student studies math problems all day and then drinks to the point of blacking out that night, chances are he will have to relearn all those problems once the alcohol has left his system, Swartzwelder said.

"People joke about blackouts, but they represent a serious neurological insult," he said. "If you took a blow to the head hard enough to disrupt memory, you'd be really worried."

Swartzwelder has looked for a biological explanation for the alcohol-fueled impairment of the hippocampus. He has extracted that part of a rat's brain and given it enough oxygen, glucose and other fluids to mimic ordinary life. He then adds alcohol and measures the electric currents in those brain cells. "Cells start to quiet down and the circuits stop responding," he said.

Swartzwelder cannot say whether alcohol-fueled deficiencies in learning and memory will persist, but another study he's done is suggestive. He compared adult rats that had been given alcohol during adolescence with adult rats that had never been given it. When both were then exposed to alcohol, the first group was more resistant to alcohol's sleepiness effect - an effect that naturally can limit alcohol consumption - and they also showed more impaired learning and memory skills.

This suggests, he said, that "you are changing the wiring of the brain with repeated alcohol exposure during adolescence."

Michael Taffe, an associate professor at the Scripps Research Institute in La Jolla, Calif., has also looked at the structure of brains exposed to alcohol and found a slowing in the growth of brain cells that transmit signals.

Taffe analyzed two groups of monkeys, one given an alcohol-Tang mixture to drink and one just plain Tang. He then tested how well each group could learn, remember and repeat a pattern on a touch-screen computer test. The group fed the alcohol could follow the pattern for five seconds before falling off in accuracy; the non-alcohol group lasted 20 seconds. Taffe then looked at the brains of these monkeys and found that the heavy drinkers had made fewer new neurons.

"We think there is a connection between the hippocampus and different kinds of memory tasks," Taffe said. "We think there is likely neurobiological damage, and what we saw is plausibly related to behavioral changes."

Dings in white matter

Eight years ago, Susan Tapert, a professor of psychiatry at the University of California at San Diego, started following a group of 28 people who were then 12 to 14 years old. Half had already engaged in binge drinking and half had not. For her study, Tapert each year took MRI scans of the brains of both groups and had the two groups take various cognitive and skill tests.

Among the drinkers, Tapert began to find small abnormalities in their MRIs that looked like ding marks in their brain's white matter - on the fatty myelin coating of the axons, the connecting fiber between neurons. Axons allow messages to flow to and from neurons, and the insulated myelin coating speeds the transmission. So if the myelin is compromised, Tapert hypothesized, students wouldn't perform as well on cognitive and memory tests. That turned out to be the case.

"We're seeing reduced quality of white matter in adolescents who engage in heavy drinking," she said. "White matter is important for cognitive abilities. The more these axons are coated with myelin, the more efficiently information is relayed."

"Alcohol is linked consistently with poor performance on a range of tasks, including sequencing, verbal and spatial functions, and math tasks," she said. "Students have trouble with putting together a puzzle, building a bookcase, reading a map, also higher-order thinking and organizing, such as, 'I have all this homework. How am I going to organize it and get it done?' We can see a 10 percent reduction in cognitive ability and brain health on many of these measures."

Tapert thinks that this reduced brain power could be permanent but that more research needs to be done to fully understand what is going on. She and others are looking at whether "the abnormalities we have observed in binge drinkers abate with abstinence." So far, "we have seen that the white-matter abnormalities are not normalized after just six weeks," but that might change over time.

In the meantime, DeRiso and others say they expect ERs will continue to treat too many young people for alcohol poisoning, injuries or worse.

"You don't know how many kids I've seen who are never the same," said Montgomery County police officer William Morrison, who heads the department's alcohol initiative unit. "They never go back to school, they have brain damage, they stop breathing."

Students say the culture of binge drinking is not about to change. "The first weekend of freshman year, there is a huge amount of drinking," said Benjamin Palacios, a senior at Vassar College whose family lives in Chevy Chase. "At Halloween parties last year, 17 kids were sent to the hospital."

Young people think of drinking as "quite 'cool,' " he said. "And as long as it is, kids will take it as far as they can."

Hambleton is a freelance writer and editor, and a documentary filmmaker in Chevy Chase.

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