Why boys tend to be callous and display unemotional traits? New research has zeroed in on their brain structure, which is entirely absent in girls, though they have shown such traits now and then.
A European research team led by the University of Basel and University of Basel Psychiatric Hospital in a study on brain development in 189 adolescents, said the callous and unemotional traits in boys have been linked to deficits in the development of the conscience and of empathy in their brains.
The report published in the journal "Neuroimage: Clinical" said children and adolescents react less to negative stimuli as they often prefer risky activities and show less caution or fear. Until now, researchers and doctors have attributed these personality traits to the development of more serious and persistent antisocial behavior.
Using magnetic resonance imaging (MRI), the researchers were able to take a closer look at the brain development of typically-developing 189 teenagers to find out whether callous-unemotional traits are linked to differences in brain structure. They tried to find out if the relationship between callous-unemotional traits and brain structure differs between boys and girls.
True to their belief, the findings show that in boys, the volume of the anterior insula – a brain region implicated in recognizing emotions in others and empathy – is larger in those with higher levels of callous-unemotional traits. This variation in brain structure was only seen in boys, but not in girls with the same personality traits.
"Our findings demonstrate that callous-unemotional traits are related to differences in brain structure in typically-developing boys without a clinical diagnosis," said lead author Nora Maria Raschle from the University and the Psychiatric Hospital of the University of Basel in Switzerland.
Differences in reports of increased or decreased gray matter in anterior insula in community samples of boys, or boys as compared to girls, with elevated callous-unemotional-traits may reflect the delayed maturation of this region in males, the study noted.
"In a next step, we want to find out what kind of trigger leads some of these children to develop mental health problems later in life while others never develop problems," Raschle said.