Two preliminary reports, being presented today in Chicago at the Radiological Society of North America (RSNA) annual meeting, found that the aggressive teens had different activity patterns in the frontal lobe portion of their brain while playing violent video games, differences that might be explained by different structures.
The frontal lobe section of the brain is involved in impulse control, attention and other cognitive activities.
"These are very important studies," says John P. Murray, professor of developmental psychology in the School of Family Studies and Human Services at Kansas State University in Manhattan, Kan. "Adolescents with DBD have long been suspected of having frontal lobe abnormalities, and these studies confirm unusual patterns of activation and structural differences in aggressive adolescents."
Disruptive Behavior Disorders refer to a group of often-dangerous behavioral problems affecting both children and adolescents. They can include oppositional defiant disorder (or ODD, characterized by hostility and hyperactivity, among other things) as well as conduct disorder (which can encompass substance abuse, weapon use and other antisocial behaviors). According to the study authors, ODD affects an estimated 5-to-10 percent of children, while conduct disorder affects about four percent of teens aged 13-to-16.
In the first study, the researchers used functional magnetic resonance imaging (fMRI) to look at patterns of brain activity of the adolescents with DBD and aggressive behavior while they played a violent (James Bond) video game and while they played an exciting but nonviolent video game (a car race game).
Overall, the aggressive adolescents had less activation in the frontal lobes and less overall brain activation than their normal counterparts.
According to Dr. Vincent Mathews, the principal investigator in the study, this is the first evidence that adolescents with aggression and DBD have different brain activation patterns.
The researchers also found differences depending on how much previous exposure the adolescents had to violent television, movies, video games and the media.
"It didn't exactly mimic the differences between controls and aggressive subjects, but there were some differences," says Mathews, a professor of radiology and chief of neuroradiology at Indiana University School of Medicine in Indianapolis.
In the second study, a different group of aggressive, DBD teens underwent magnetic resonance diffusion tensor imaging (DTI) to map the structure of the brain. As it turned out, these adolescents had abnormal development of the white matter in the brain's frontal lobes compared with the controls. The brain's white matter covers the brain's nerve cells, acting as an insulator and catalyzing the transmission of nerve signals.
"Both the studies showed differences in the frontal lobes of the disruptive behavior disorder adolescents who also had aggressive features and the normal controls," Mathews says. "There were differences in the structure of white matter and also differences in brain activation while playing the video game."
But Mathews cautions that both of these studies were also observational, meaning that no firm conclusions can be drawn regarding whether the frontal lobe differences actually affect behavior.
Previous studies have suggested that differences in frontal lobe function might explain behavioral problems.
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For even more information, including research studies on how television violence affects the brain, visit John Murray's web site.