RENEE MONTAGNE, host:
This is MORNING EDITION, from NPR News. I'm Renee Montagne.
Today in "Your Health," we'll tell you about a new study that shows how quickly first-time smokers get addicted to tobacco, and a cautionary tale for parents about drinking. And let's get to that story now.
As teenagers reach their senior year of high school, some parents begin to feel more comfortable about permitting their teens to drink alcohol. But new research from brain scientists and parenting experts suggests loosening the reins on drinking may not be a good idea in the long run. Reporter Michelle Trudeau has more.
MICHELLE TRUDEAU: Researchers say that the longer a teenager delays drinking alcohol, the safer it is for the teen's brain. That's because the adolescent brain is still growing. Brain cells are still developing well into the mid-20s in brain areas that control decision-making and problem-solving.
Research from Susan Tapert at the University of California, San Diego shows that heavy drinking can cause physical changes to these parts of the teen brain long after the intoxication wears off.
Professor SUSAN TAPERT (Psychiatry, University of California, San Diego): We've seen that adolescents who engage in binge drinking - so that's having five or more drinks on an occasion for boys, or four or more drinks on an occasion for females - tend to show some brain abnormalities in their brain's white matter, so those fibers that connect different parts of the brain.
TRUDEAU: And if binge drinking continues a couple of times a month, within two to three years, Tapert says, it can result in subtle declines in the teen's thinking.
Prof. TAPERT: We've seen that teenagers who start heavy drinking begin to go downhill relative to kids of the same age who do not start heavy drinking - on different measures of cognitive performance.
TRUDEAU: Downhill in problem-solving, attention and memory. Keep in mind, there's a lot of variability between individuals, Tapert says, but she concludes that for some teens, there may be no safe level of alcohol use. She saw negative effects in thinking and memory in teens after as little as 12 drinks a month, or two or three binge-drinking episodes a month.
But here's another question: What type of parental guidance results in teens postponing drinking, or in less binge drinking when they do drink? Research in the U.S. and Europe has some answers.
Alcohol researcher Caitlin Abar, from Penn State University, has studied how parents deal with their teens in high school regarding drinking and then checked again after the kids' first semester of college. Her study of 300 teenagers and their parents appeared recently in the journal�"Addictive Behaviors."
Professor CAITLIN ABAR (Penn State University): Parents who disapproved completely of underage alcohol use tended to have students who engaged in less drinking - less binge drinking once in college.
TRUDEAU: And conversely, a parent's permissiveness about teenage drinking is a significant risk factor for later binge drinking.
Prof. ABAR: The parents who are more accepting of teen drinking in high school were more likely to have children who engaged in risky drinking behaviors in college, compared to those children who had parents that were less accepting.
TRUDEAU: Abar also asked the teens about their parents' drinking.
Prof. ABAR: So how often they witnessed their parents' drinking in the home and on those occasions, how much alcohol did they witness their parents' consuming.
TRUDEAU: Results? Parents' own drinking did influence a teen's drinking. But parents' rules still had the greatest effect. Complete disapproval of teen drinking was the most protective, even more than when parents allowed a limited amount of teen alcohol consumption.
Studies by Mark Wood, from the University of Rhode Island, support these findings. Wood adds that parental monitoring - knowing where your teenager is, who they're with, what they're doing - also pays off, in terms of alcohol use, when teens go off to college.
Professor MARK WOOD (Psychology, University of Rhode Island): The protective effects that parents exert in high school continue to be influential into college, even at a time when the kids have left the home. I mean - so it's the internalization of those values, attitudes, expectations that seem to continue to exert an effect.
TRUDEAU: These studies challenge the common parenting practice in much of Europe, where kids are socialized to drink at the family table, with the expectation that they'll learn to drink responsibly. Dutch researcher Haske van der Vorst.
Dr. HASKE VAN DER VORST (Researcher): A lot of parents have the idea like, if I let my child drink at home, you know, with friends, then at least, you know, I can control it somehow. Even if I then buy the alcohol myself. Then I am in control.
TRUDEAU: Unfortunately, says van der Vorst, the European model isn't working. She's looked at teen drinking at home and then again three years later, once the kids were out of the house.
Dr. VAN DER VORST: The more teenagers drink at home, the more they will drink at other places, and the more - the higher the risk for problematic alcohol use.
TRUDEAU: She notes a recent survey of drinking by 15- and 16-year-olds in Europe, showing that the majority of European countries have a higher rate of teen drunkenness than this country. U.S. researcher Caitlin Abar says that having a zero-tolerance policy at home doesn't prevent teens from drinking, but she says kids from those households tend to drink less, both at home and in college.
For NPR News, I'm Michelle Trudeau.