Pupil Response to Affective Stimuli: a Biomarker of Early Conduct Problems in Young Children.

Childhood conduct problems have been associated with reduced autonomic arousal to negative cues indicative of an insensitivity to aversive stimuli, with mixed evidence in response to positive cues. Autonomic arousal to affective stimuli has traditionally been measured through galvanic skin responses and heart-rate, despite evidence that pupillometry is more reliable and practically beneficial (i.e., no wires are attached to the participant). The current study is the first to examine abnormal pupillary responsivity to affective stimuli as a biomarker for childhood conduct problems. We measured pupil reactivity to negative, positive and neutral images in 131 children aged 4-7 years, who were referred by their teachers for being at risk of future psychopathology. We assessed relationships between pupil response to the images and teacher-rated scores on the Strengths and Difficulties Questionnaire (SDQ), which indexed child conduct problems and their overlapping emotional, behavioural and social difficulties. Reduced pupil dilation to negative images was associated with significantly increased conduct, hyperactivity, emotional and peer problems, as well as reduced prosocial behaviour. Composite scores for disruptive behaviour and emotional difficulties both uniquely predicted blunted pupil response to negative threat stimuli; there were no relations with pupil responses to positive images. These findings highlight that blunted pupil responsivity to negative stimuli serves as a biomarker for early disruptive behavioural problems and affective difficulties. Pupillometry offers an inexpensive, fast and non-intrusive measure to help identify children who are showing early disruptive behaviour or experiencing affective difficulties, which can provide opportunities for preventative intervention to avoid further psychopathology.