Pubdate: Tue, 24 Jun 2003
Source: New York Times (NY)
Copyright: 2003 The New York Times Company
Contact:  http://www.nytimes.com/
Details: http://www.mapinc.org/media/298
Author: John O'Neil

DRUG ADDICTION AS A DEVELOPMENTAL DISORDER

A new study from Yale suggests that drug addiction should be thought of as 
a developmental disorder, because the changing circuitry of teenagers' 
brains appears to leave them especially vulnerable to the effects of drugs 
and alcohol.

Dr. R. Andrew Chambers of the Yale School of Medicine, lead author of the 
article, said addictive drugs worked by stimulating parts of the brain that 
are changing rapidly in adolescence.

In particular, Dr. Chambers said, the drugs tap into a neural imbalance 
that may underlie teenagers' affinity for impulsive and risky behavior. The 
circuitry that releases chemicals that associate novel experiences with the 
motivation to repeat them develops far more quickly in adolescence than the 
mechanisms that inhibit urges and impulses.

As a result, he said, teenagers are not only more likely to experiment with 
drugs than other groups, but the experience also has more profound effects 
on the brain - and sometimes permanent ones.

The article, published in the June issue of The American Journal of 
Psychiatry, was based on a review of 140 earlier studies. Dr. Chambers 
wrote that although it had long been known that most addicts began using 
drugs in adolescence, most research into the mechanisms of addictions or 
treatment focused on adults.

Shifting to a model that links vulnerability to normal developmental 
changes in the brain could lead to new methods of prevention or ways of 
singling out teenagers at higher risk for drug use, he said.

Dr. Chambers acknowledged that social factors appeared to play a role in 
drug addiction but said they did not account entirely for greater levels of 
drug use among adolescents.

His analysis covered three aspects of teenage behavior and their basis in 
brain functioning - attraction to novelty, less than adult levels of 
judgment and an overriding interest in sex. Teenagers are drawn to new 
activities and experiences, a process that Dr. Chambers referred to as "the 
expansion of their motivational repertory."

"That's a good thing," he said, "because adolescents have to learn how to 
be adults." But to aid the process, the motivational circuitry of the brain 
- - the complex of chemical reactions that make certain experiences more 
desirable than others - is also rapidly expanding. It is this circuitry, 
centered on the chemical dopamine, that is at the heart of the addictive 
effects of a wide range of drugs as different as cocaine and alcohol, Dr. 
Chambers said.

At the same time, the parts of the frontal cortex that are activated by 
adults when they weigh risks and rewards lag developmentally.

"You have a situation where the motivational brain areas are particularly 
active," Dr. Chambers said, "and the part of the brain that is supposed to 
inhibit impulses is not working well, because it is sort of under 
construction."

The other part of the equation lies in a number of brain regions that are 
reshaped in adolescence as they respond to soaring levels of sex hormones. 
Dr. Chambers said that rapid change seemed to leave young people unusually 
attuned to all sorts of new social and sexual stimulation, which in turn 
appeared to make the brain more open to the addictive effect of drugs.
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MAP posted-by: Larry Stevens