Thursday, September 17, 2009

Daredevil Behavior and the Teenage Brain

Teenagers are often assumed to be risk-takers who engage in dangerous and idiotic activities. And that is often true. But compared to American adults, they are really not that bad.

It is often assumed that it is due to their "underdeveloped brains," which apparently continue to develop until at least age 25. This factoid is heard so often that it is taken as gospel. Indeed, numerous studies have revealed changes in the adolescent and young adult brain. So one must lead to the other, right?

But what if the supposed causation is not just inaccurate, but in fact is 100% wrong? Apparently, a new study of brain imaging suggests just that. They found that the more mature and "adult" the white matter of teen brains was, the more risk-taking behavior reported, the opposite of what was expected. Of course, the direction of causality is uncertain, but doesn't this blow a hole in the conventional wisdom?

Another study finds that, among 10-16 year olds, shortsightedness is not caused by impulsivity (lack of self-control), but rather by sensation-seeking. While 10-16 year olds did tend to think about the future less than adults do, and thus prefer immediate rewards to delayed ones, there was little change in shortsightedness after 16 (the study looked at 10-30 year olds). This is interesting since the parts of the brain that are related to sensation do not continue maturing after 16, but the parts responsible for self-control do. Still, shortsightedness changes little between the ages of 16 and 30.

The results of another study imply that, at least in terms of resistance to peer influences, 18 year olds are essentially just as competent as 23-30 year olds.  This echoes older studies that found that results on tests that measure competence to stand trial seem to level off after age 16, similar to the way IQ typically does.

Another study found that the likely explanation of the relationship between age at first drink and subsequent drinking problems has to do with the quality of the parent-child relationship. In other words, the better the quality, the later drinking begins and the fewer drinking problems. Age at first drink may simply be a marker for later problems or lack thereof, since it appears to be a marker for the relationship quality. Still another study finds that child maltreatment is independently linked to adolescent "binge" drinking (5+ drinks/occasion), as was the pink elephant in the room (parental alcoholism).

What does all this have to do with the 21 drinking age? Plenty. Arguments supporting a drinking age higher than the age of majority do not appear to hold water upon closer examination.

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