The largest imaging study of the human brain ever conducted is helping researchers understand why some teenagers start smoking or experimenting with drugs and others don’t. NARSAD grantee Mark Bellgrove, Ph.D. Associate Professor, School of Psychology at University of Queensland in Australia, was part of an international team of researchers that discovered a number of previously unknown networks in the brain that provide strong evidence that some teenagers are at higher risk for drug and alcohol experimentation than others because their brains are wired to make them more impulsive. The findings, published online in Nature Neuroscience on April 29, were based on studies of 1,896 14-year-olds whose brains were scanned using functional MRI imaging (fMRI). The scans revealed that diminished activity in a network involving the orbitofrontal cortex in the brain is associated with experimentation with alcohol, cigarettes and illegal drugs in early adolescence.

Using a complex mathematical approach called factor analysis the researchers were able to identify seven networks involved when impulses were successfully inhibited and six networks involved when inhibition failed—from the vast and chaotic actions of a teenage brain at work. They 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. Edythe London, Professor of Addiction Studies and Director of the UCLA Laboratory of Molecular Pharmacology, who was not part of the new study, described it as "outstanding," noting that it "substantially advances our understanding of the neural circuitry that governs inhibitory control in the adolescent brain."