FRIDAY, Sept. 29, 2017 (HealthDay News) -- A child's inability to laugh with others could point to psychopathic behavior later, a new study suggests.
Most people find it natural to join in when they see or hear others laughing, the researchers noted. But laughter isn't contagious for boys at risk of developing psychopathy later in life, the researchers found.
"Those social cues that automatically give us pleasure or alert us to someone's distress do not register in the same way for these children," said lead author Essi Viding, of University College London in England.
"That does not mean that these children are destined to become antisocial or dangerous; rather, these findings shed new light on why they often make different choices from their peers," Viding said.
Until now, most studies have focused on how individuals with psychopathic traits process negative emotions and how their lack of response to them might explain their aggression, Viding said.
"This prior work is important, but it has not fully addressed why these individuals fail to bond with others," she added. "We wanted to investigate how boys at risk of developing psychopathy process emotions that promote social affiliation, such as laughter."
The study included 62 boys aged 11 to 16 with disruptive behaviors with or without "callous-unemotional traits" -- a general disregard for others. They were compared with a control group of 30 normally behaved boys.
People at risk of psychopathy later in life have persistent disruptive behaviors and callous-unemotional traits, the researchers explained.
The boys with those tendencies said they were less eager to join in with laughter than those who were disruptive but who did not have callous-unemotional traits, and those in the control group, the study found.
Brain scans also revealed that these boys had a reduced response to the sound of laughter. Those differences were detected in brain areas that promote joining in with others and resonating with other people's emotions.
The study was published Sept. 28 in the journal Current Biology.
"It is not appropriate to label children psychopaths," Viding said in a journal news release. "Psychopathy is an adult personality disorder. However, we do know from longitudinal research that there are certain children who are at a higher risk for developing psychopathy, and we screened for those features that indicate that risk."
The findings reveal that children who are at risk of developing psychopathy don't experience the world quite like others do, she said.
"We are only now beginning to develop an understanding of how the processes underlying prosocial behavior might differ in these children. Such understanding is essential if we are to improve current approaches to treatment for affected children and their families who need our help and support," Viding said.
Mental Health America has more on personality disorder.