Teenagers with brothers and sisters who exhibit severe antisocial behavior share a similar impairment with their siblings in recognizing emotions, according to a new study from the University of Southampton.

The findings suggest that difficulties in recognizing emotions could be a factor that increases a child's risk of developing conduct disorder - a condition characterized by pathological aggression and antisocial behavior.

Previous studies have shown that children and adolescents with conduct disorder (CD) find it difficult to identify facial emotions in others such as anger, fear and happiness. But new research, published today in the journal Psychological Medicine, reveals that the siblings of children with conduct disorder, who display no symptoms themselves, also struggle to recognize certain emotions.

As the brothers and sisters of those with CD are significantly more likely to develop antisocial behavior themselves, the findings suggest that similar difficulties in facial emotion recognition could be a factor that contributes to this increased risk.

"Young people with Conduct Disorder place a greater burden on legal, healthcare and educational services than their typically developing peers," says the University of Southampton's Dr Graeme Fairchild, who led the study. "It is vital to understand the underlying factors behind this condition that might explain why antisocial behavior sometimes runs in families.

"The ability to recognize emotions in others is vital for successful non-verbal communication and social interaction. Our findings suggest that difficulties in reading emotions in others could be a risk factor in the development of CD."

The researchers studied facial emotion recognition in 107 teenagers, divided into three groups: 39 healthy control subjects, 44 adolescents diagnosed with conduct disorder, and 24 unaffected siblings with a brother or sister who has conduct disorder but who have no history of antisocial behavior themselves.

The teenagers with conduct disorder struggled to recognize anger, fear, happiness, sadness and surprise in facial expressions, in line with findings from previous studies. The non-antisocial siblings of those with conduct disorder also showed impaired recognition of anger, happiness, and to a lesser extent fear, when compared with the control group.

Dr Fairchild commented, "If impaired facial emotion recognition is a risk factor for Conduct Disorder, further research is needed to determine why some relatives with similar genetic and environmental risk factors might develop Conduct Disorder while others remain unaffected, despite exhibiting similar problems in emotion recognition."