Teen Brains & Drinking

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Teenage binge drinking may cause significant and permanent brain damage.


A peril of teenage drinking. I'm Bob Hirshon and this is Science Update.

Research suggests that teenage binge drinking has an intellectual price. The latest comes from psychiatrist Susan Tapert of the
University of California at San Diego. Her team evaluated middle schoolers who hadn't started drinking, and then tracked them for several years. Those who began to drink heavily showed visible damage to their brain's white matter—the tissue that relays information. And that's not all.

We found that those who initiated heavy drinking began to perform more poorly on several kinds of tests.

She says girls who drank heavily fell behind on spatial tasks, compared with their non-binging peers. But binge-drinking boys suffered in their attention to detail. Tapert says the difference may reflect areas of relative vulnerability for each gender. I'm Bob Hirshon for AAAS, the Science Society.

Making Sense of the Research

Teen binge drinking poses a number of dangers. Obviously, heavy drinking can lead people to engage in high-risk behaviors, and teenagers tend to be more likely than adults to take reckless risks. Scientists have also long been concerned that the still-developing teenage brain is more vulnerable to damage from alcohol than a fully mature adult brain. 

But while past studies have compared teenage drinkers to non-drinkers, there had been relatively few prospective studies of teen drinking. A prospective study is one that tracks a group of people for many months or years, starting from a point before the relevant disease or condition develops. Then the researchers watch to see who develops the condition and when, and relate it to possible risks or protections that made the condition more or less likely. In contrast, a retrospective study compares a group of people with the condition to a group of people without it, and looks back in time for differences in each group's risk factors. Prospective studies can be more revealing and meaningful than retrospective studies, but they are more expensive and difficult to conduct. 

In a sense, a prospective study is the equivalent of a laboratory experiment—usually one that could not be conducted for ethical reasons. In this case, for example, you couldn't start with a group of twelve-year-olds and order half of them to start binge drinking over the next several years. However, in a prospective study, you can simply follow the individuals and examine the consequences of their own choices. 

One of the key findings of this study is that teenagers who began binge drinking (defined as having four to five alcoholic drinks per occasion, two or three times per month) wound up performing more poorly on intellectual tests as they got older. Because this was a prospective study, this can't be explained away by saying that kids who drink heavily usually aren't so bright to begin with. That's because before they started drinking, the exact same kids scored about as well as their peers who didn't go on to become binge drinkers. In other words, there's a direct correlation between taking up binge drinking and declining intellectual performance. The difference in performance, according to Tapert, is about the equivalent of going from an "A to a B."

The researchers also looked at brain scans of some of the teens, and found that the heavy drinkers had blemishes that indicated damage to the brain's white matter. White matter is one of two categories of brain tissue (the other is gray matter). The gray matter consists of nerve cell bodies, while the white matter is the wiring between the cells. White matter is vital for learning, which involves forging new connections between different parts of the brain, and unlike gray matter, it continues to develop well into middle age. If the white matter damage in teenage binge drinking is permanent, it could limit their capacity for learning in adulthood. 

At the end of the story, you heard that binge drinking affected boys and girls differently. Girls got worse at spatial tasks, while boys got worse at tasks requiring attention to detail. Generally speaking, girls score slightly better than boys at attending to detail, while boys slightly outperform girls in spatial processing. So it's possible that the brain damage caused by heavy drinking has a more obvious effect on mental skills that aren't quite as strong as others.

Now try and answer these questions:

  1. What is a prospective study? How does it differ from a retrospective study?
  2. Why does this study indicate that drinking itself may have caused the brain damage?
  3. What is the significance of the gender differences in the study's result?
  4. Do you think teenagers are more prone to binge drinking than adults? Why or why not?

For Educators

In the Science NetLinks Science Update lesson Adolescent Slowdown, learn why a slowdown in brain function may play a role in adolescence.

The Science NetLinks Science Update lesson Drug Cravings explores why drug habits can be so hard to kick.

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