Vol. 9, No. 1, 2003 Page 1
Adolescents with disruptive behavior disorders (DBDs) appear to have different brain structures than other adolescents and show different brain activity when exposed to violence, according to two recent studies by the same research group.
In the first study, Vincent Mathews and colleagues used functional magnetic resonance imaging (fMRI) to evaluate brain activation patterns in normal teens and those with DBDs in response to stimuli from violent or non-violent video games. Subjects included 19 controls and 19 adolescents with either conduct disorder or oppositional defiant disorder. (Conduct disorder is characterized by violent behavior, physical or sexual aggression, substance abuse, cruelty to animals and people, and related behavior, while oppositional defiant disorder is characterized by verbal aggression, hostility, impulsiveness, and defiance of authority.)
The researchers detected different amounts and patterns of brain activity in the troubled teenagers, who showed less overall brain activation, and in particular less activation in the frontal lobes, in response to violent games. "This is the first evidence," Mathews says, "that adolescents with aggressive, disruptive behavior disorders have brain activation patterns that are different from non-aggressive adolescents."
Initial results from a related study by this research group indicate that structural brain differences underlie the unusual responses of adolescents with DBDs. Mathews et al. evaluated 18 controls and 11 teens with DBDs using magnetic resonance diffusion tensor imaging (DTI) to map white matter structure and connections between brain regions.
The researchers report that preliminary findings show that adolescents with DBDs have abnormal white matter development in the brain's frontal lobes. "Potentially, the structural differences we found in the brains of the adolescents diagnosed with disruptive behavior disorders could account for their behavior problems," says Mathews. "This may be part of the explanation as to why we see differences in activation through fMRI and also differences in behavior in society."
According to the researchers, five to ten percent of children have oppositional defiant disorder, and four percent of teenagers between the ages of 13 and 16 are diagnosed with conduct disorder.
"Violent video games trigger unusual brain activity in aggressive adolescents," Vincent Mathews et al., presentation to the annual meeting of the Radiological Society of North America, Dec. 2, 2002.