Facial EMG responses to dynamic emotional facial expressions in boys with disruptive behavior disorders

Based on the assumption that facial mimicry is a key factor in emotional empathy, and clinical observations that children with disruptive behavior disorders (DBD) are weak empathizers, the present study explored whether DBD boys are less facially responsive to facial expressions of emotions than normal controls. Facial electromyographic (EMG) activity in the zygomaticus major and corrugator supercilii muscle regions, and heart rate activity were studied in 22 clinically referred 8-12-year-old DBD boys and 22 age-matched normal controls during exposure to dynamic happy and angry expressions. Dispositional emotional empathy was assessed by a self-report questionnaire for children. The happy and angry facial expressions evoked distinct facial EMG response patterns, with increased zygomaticus muscle activity to happy expressions and increased corrugator muscle activity to angry expressions. The corrugator (but not the zygomaticus) muscle response pattern was less pronounced for DBD boys than the normal controls. Attending to the emotional expressions was associated with equivalent cardiac deceleration in both groups, reflecting a similar orienting/attention response. Lower empathy scores were obtained for DBD boys than for normal controls. In conclusion, facial mimicry responses to angry facial expressions were subnormal in DBD boys, which may be a sign of a deficient early component in the process of emotional empathy, and thus play a role in impaired empathic responding.