What is the relationship between behavioral disorder and small brain size in children?

A new study has revealed that naughty children may have smaller brains than their well-mannered peers.

Researchers from the Royal College of Psychiatrists found that young children who lie, steal, fight, bully others and treat animals cruelly had smaller surface areas in 26 out of 34 brain regions.

Disruptive behavior in children is called "conduct disorder."

Children with the disorder had less overall surface area across the outer layer of the brain, and in the amygdala, hippocampus and thalamus, all of which help regulate behavior.

The largest number of brain changes were seen in children, who showed low levels of empathy, guilt and remorse.

Although it is unclear why the brain regions of children who misbehave change, researchers say it may be due to childhood adversity and/or abuse.

“We know so little about this disorder that we thought it could place a huge burden on families and communities,” lead author Yidian Gao told The Times. “It provides the most compelling evidence yet that conduct disorder is linked to widespread structural differences in the brain.”

The study was published in The Lancet Psychiatry.