Teenagers tend to push the envelope, it’s a part of growing up, beginning to explore and investigate for oneself and not just taking instructions like a child. The trait is obvious and has its benefits. It is seen in all cultures and even in the animal kingdom. As offspring start to mature it is necessary for them to make their own choices and learn from their mistakes.
However, what is less understood is why some teenagers have a tendency to be super rebellious, driving parents and teachers to distraction. Of course, an obvious outlet for rebels is drinking, smoking and drug taking. Now we are starting to have some real answers.
Robert Whelan and Hugh Garavan of the University of Vermont, along with a large group of international colleagues, conducted the largest brain imaging study in history, enrolling nearly 2,000 14 year old subjects.
Whelan explains:
“These networks are not working as well for some kids as for others.”
His colleague in UVM’s psychiatry department, 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 continues:
“The differences in these networks seem to precede drug use. “
Getting into more depth, the researchers explain that an area of the brain called the “orbitofrontal cortex” (OFC) is associated with those trying, smoking, drinking and party drugs. In short, the OFC acts as a regulator for regulating the network, so that an idea is not acted on immediately. Those with a less active OFC tend to jump straight into new possibilities without regard.
Although it might tend to lead to a Gattaca style existence (A science-fictional world where everyone is screened and statistically allocated responsibilities, according to their biological makeup), the concept is certainly useful for understanding and identifying children that are at risk as they enter their teen years.
Accidental death amongst teens is the leading cause of death and research has shown it to be rooted in drinking and drugs. For example, risk taking, starting with getting drunk, then stealing a car and crashing it. Catching the trait and identifying those at risk sooner in their lives would greatly assist with public health.
The ADHD picture has also been clarified by Whelan’s work, with the scans picking the ADHD problem as separate from the weaker OFC, impulsive filtering process. Scientists showed that both teens with and without signs of ADHD can perform badly on what they call “stop-signal reaction time”, a measure of inhibitory control. Thus, children with ADHD are not automatically at risk of becoming drug takers or rebels. They just have problems concentrating.
The impulsivity networks were revealed by looking at blood flow in the brain, and have given researchers a much clear picture of how we choose to act on or reject an impulsive idea. The teens were asked a series of questions while inside the MRI scanner, and asked to push a button to stop the process. When they pushed the button quickly enough, they had seven of these centers showing increased blood flow, while those failing had only six centers.
Garvan concludes:
“The take-home message is that impulsivity can be decomposed, broken down into different brain regions … and the functioning of one region is related to ADHD symptoms, while the functioning of other regions is related to drug use.”
One of the greatest successes of the study was due to its size, because the massive amount of activity in a teenagers brain would not have allowed identification of these centers. It was the volume of test subjects that allowed scientists to pinpoint the brain activity.
The new study draws on the multi-year work of the IMAGEN Consortium, funded by the European Union, and headed by Prof. Gunter Schumann at the Institute of Psychiatry, King’s College London. IMAGEN, lead by a team of scientists across Europe, carried out neuroimaging, genetic and behavioral analyses in 2,000 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.
Written by Rupert Shepherd