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DEVELOPING BRAINS OF TEENS, YOUNG ADULTS INCREASE VULNERABILITY TO SUBSTANCE ABUSE
Experts often blame substance abuse by teens and young adults on
peer pressure and the stresses of moving from youth to adulthood. A
new study, however, argues that young people's vulnerability to drug
abuse stems in large part from biological rather than sociological
factors.
R. Andrew Chambers and colleagues note that teens and young
adults experiment with and become addicted to drugs and alcohol far
more often than older adults, and that adult substance abuse generally
begins in the teen or early adult years. In addition, they point out, early
onset of substance abuse predicts greater severity. The researchers say
scientific evidence shows that sociocultural factors cannot fully account
for these patterns, which are seen across cultures and are true for both
males and females.
The researchers believe that this enhanced vulnerability of
adolescents and young adults to substance abuse stems from
developmental changes in the brain circuitry underlying motivation,
impulsivity, and addictive behavior. Reviewing more than 140 studies on
adolescent brain development and related research, the researchers
conclude that "particular sets of brain circuits involved in the
development of addictions are the same ones that are rapidly undergoing
change during adolescence. Normally, these processes cause
adolescents to be more driven than children or adults to have new
experiences. But these conditions also reflect a less mature neurological
system of inhibition, which leads to impulsive actions and risky
behaviors, including experimentation and abuse of addictive drugs."
Developmental changes that can increase vulnerability to substance
abuse, the researchers say, include:
- Greater activity of the dopamine system, which promotes exploratory
behavior, than the serotonin system, which helps to inhibit impulsive
behavior.
- Changes in sex steroid levels. The researchers note that sex steroid
receptors are highly expressed in the hippocampus, a brain region
involved in the detection of and behavioral response to novel situations.
"A major implication of this model," Chambers and colleagues say, "is
that substance use disorders constitute neurodevelopmental disorders."
They suggest that while "psychiatrically compromised" teens are at the
highest risk for substance abuse, all adolescents are vulnerable to some
degree. "Here we have a phenomenon," say Chambers et al., "where a
neurodevelopmental stage common to virtually everyone regardless of
genetic make-up confers enhanced neurobiological vulnerability to
addiction."
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"Developmental neurocircuitry of motivation in adolescence: a critical
period of addiction vulnerability," R. Andrew Chambers, Jane R. Taylor,
and Marc N. Potenza, American Journal of Psychiatry, Vol. 160,
No. 6, June 2003, 1041-52. Address: R. Andrew Chambers, Connecticut
Mental Health Center, 34 Park Street Third Floor, New Haven, CT
06508, robert.chambers@yale.edu.
--and--
"Adolescents are neurologically more vulnerable to addictions," press
release, Yale University, June 18, 2003.
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