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Boys tend to have more unemotional traits than girls, reveals a new research. Their unemotional traits characterised by lack of empathy, disregard for others' feelings and shallow or deficient affect, lack of remorse or guilt has been linked to their difference in brain structure.

The findings of the new study show that in typically-developing boys, the volume of the anterior insula or grey matter — a brain region implicated in recognising empathy and emotions in others, 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 of Basel in Switzerland.

They came to the conclusion after taking a closer look at the brain development of typically-developing 189 teenager participants, using Magnetic Resonance Imaging (MRI).

 They found a link between callous-unemotional traits and brain structure differs between boys and girls.

"Differences in reports of increased or decreased grey matter in anterior insula in community samples of boys, or boys as compared to girls, with elevated callous-unemotional-traits may reflect maturational effects (i.e. delayed maturation of this region in males)," the study noted.

The research team feels that further study is required to understand the psyche of these teens as they grow older and how the larger grey matter volume affects the personality of the teenagers once they are fully developed physically and mentally.

"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.

The journal Neuroimage: Clinical has published the results.