A new study suggests the way in which the brain is wired in some people may make them more impulsive and more likely to experiment with drugs.
In the largest imaging study of the human brain ever conducted — involving nearly 1,900 14-year-olds — scientists discovered a number of previously unknown neural networks.
Researchers lead by psychologists Drs. Robert Whelan and Hugh Garavan of the University of Vermont reported that differences in these networks provide strong evidence that some teenagers are at higher risk for drug and alcohol experimentation.
Investigators believe an individual’s neural wiring can cause some to be impulsive. Their findings are presented in the journal Nature Neuroscience.
Researchers believe this discovery helps answer a long-standing chicken-or-egg question about whether certain brain patterns come before drug use — or are caused by it.
“The differences in these networks seem to precede drug use,” said Garavan, who also served as the principal investigator of the Irish component of a large European research project, called IMAGEN, that gathered the data about the teens in the new study.
In a key finding, diminished activity in a network involving the orbitofrontal cortex of the brain 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,” said 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!” said Garavan, “and this other kid is saying, ‘no, I’m not going to do that.’”
Researchers believe that one day, scientists may be able to develop a screen for lower function in this and other brain networks could. This in turn could be used as “a risk factor or biomarker for potential drug use.”
Investigators 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. Over the years, investigators have discovered that both ADHD and early drug use are associated with poor inhibitory control—they’re problems that plague impulsive people.
However, this new research suggests that these seemingly related problems are regulated by different networks in the brain. This strengthens the idea that risk of ADHD is not necessarily a full-blown risk for drug use as some recent studies suggest.
The new understanding of brain impulsivity networks—connected areas of activity in the brain revealed by increased blood flow—helps researchers understand the complexity of attributes and behaviors that psychologists call impulsivity—as well as the capacity to put brakes on these impulses, a set of skills sometimes called inhibitory control.
“The take-home message is that impulsivity can be decomposed, broken down into different brain regions,” said Garavan, “and the functioning of one region is related to ADHD symptoms, while the functioning of other regions is related to drug use.”
The new study draws on the multi-year work of the IMAGEN Consortium. Led by a team of scientists across Europe, the team carried out neuroimaging, genetic and behavioral analyses in 2000 teenage volunteers in Ireland, England, France, and Germany and will be following them for several years, investigating the roots of risk-taking behavior and mental health in teenagers.
That teenagers push against boundaries—and sometimes take risks—is a part of adolescence. It happens in all cultures and even across all mammal species: Adolescence is a time to test limits and develop independence.
But death among teenagers in the industrialized world is largely caused by preventable or self-inflicted accidents that are often launched by impulsive risky behaviors, often associated with alcohol and drug use. Additionally, “addiction in the Western world is our number one health problem,” said Garavan.
“Think about alcohol, cigarettes or harder drugs and all the consequences that has in society for people’s health.”
Understanding brain networks that put some teenagers at higher risk for starting to use them could have large implications for public health.
Source: University of Vermont