Why do some teenagers start smoking or experimenting with drugs — when others don’t? It seems to be the way their brain is wired.
In the largest imaging study of the human brain ever conducted—involving 1,896 14-year-olds—scientists have discovered a number of previously unknown networks that go a long way toward an answer.
“Some teenagers are at higher risk for drug and alcohol experimentation—simply because their brains work differently”
Robert Whelan and Hugh Garavan of the University of Vermont, along with a large group of international colleagues, report that differences in these networks provide strong evidence that some teenagers are at higher risk for drug and alcohol experimentation—simply because their brains work differently, making them more impulsive.
This discovery helps answer a long-standing chicken-or-egg question about whether certain brain patterns come before teen drug use or are caused by it.
Network not functioning as well for some kids
In a key finding, diminished activity in a network involving the ‘orbitofrontal cortex’ is associated with experimentation with alcohol, cigarettes and illegal drugs in early adolescence.
“These networks are not working as well for some kids as for others,” says Whelan, making them more impulsive.
Faced with a choice about smoking or drinking, the 14-year-old with a less functional impulse-regulating network will be more likely to say, “yeah, gimme, gimme, gimme!” says Garavan, “and this other kid is saying, ‘no, I’m not going to do that.’”
Testing for lower function in this and other brain networks could, perhaps, be used by researchers someday as “a risk factor or biomarker for potential teen drug use,” Garavan says.
ADHD and early drug use not related, according to study
The researchers were also able to show that other newly discovered networks are connected with the symptoms of attention-deficit hyperactivity disorder. These ADHD networks are distinct from those associated with early drug use.
In recent years, there has been controversy and extensive media attention about the possible connection between ADHD and drug abuse. Both ADHD and early drug use are associated with poor inhibitory control—they’re problems that plague impulsive people.
“ADHD is not necessarily a full-blown risk for drug use as some recent studies suggest”
But the new research shows that these seemingly related problems are regulated by different networks in the brain—even though both groups of teens can score poorly on tests of their ‘stop-signal reaction time’, a standard measure of overall inhibitory control used in this study and other similar ones. This strengthens the idea that risk of ADHD is not necessarily a full-blown risk for drug use as some recent studies suggest.
The findings are presented in the June issue of Nature Neuroscience.