"Man, there's a lot of partying that most people go through in college," he says, "and most of those people make it out of that and settle down into non substance disordered patterns."
But a lot of them don't, and the reasons are not yet clear.
The researchers focused on the release of dopamine in the brain, which operates "like a general 'go' signal," they report. Drugs, sex, even video games release dopamine, stimulating the brain and making us want more. But lots of other things also generate dopamine.
Food and even stress and trauma also release dopamine, and that has set researchers off in a new direction. Dopamine isn't just released by rewarding things. It's also released by events or circumstances that may threaten our survival or way of life.
Inhibition Comes Too Little Too Late
So it isn't all about "reward and pleasure," Chambers says. Since dopamine is released by a wide variety of stimuli, there must be some common ground between such things as drugs, food, sex and stress. That common denominator, many scientists believe today, is motivation.
Motivation can either pull us back from dangerous substances, like addictive drugs, if our "mature" side of mental development is on the job, or it can push us farther into harm's way, if the kid is still in charge.
Getting high, or taking a risk, is an early motivation among adolescents who are eager to try out their walking shoes. But a little later, motivation should shift somewhat as the part of the brain that inhibits impulses matures.
But by that time, addiction may have already set in.
It's not easy being a kid.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.