No added cost: emotion recognition in comorbid ADHD and ASD

Accurately interpreting facial expressions is fundamental for social interaction, yet this ability is often impaired in adults with attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD). While research has documented these difficulties, two key questions remain: First, are these deficits specific to recognising emotions or do they reflect broader challenges in face processing? And second, does the increasingly documented co-occurrence of ADHD and ASD exacerbate these difficulties? We compared emotion discrimination thresholds (EDT) in adults with ADHD, ASD, ADHD+ASD and non-clinical comparison adults. The EDT is an unbiased measurement of emotion recognition sensitivity, measuring the amount of emotion display required for a person to correctly identify it. We measured EDT with faces gradually changing from a neutral to an emotional expression. To control for general face processing skills, we designed a non-emotional but visually similar control task with neutral faces changing gradually from human to animal until identified by the participant. Using eye tracking we were able to rule out potential differences in how the four groups of participants visually attended to facial features to recognise the emotion or animal. We showed a specific disadvantage in emotion but not animal recognition in the three clinical group. Crucially, emotion recognition deficits were not amplified by the co-occurrence of ADHD and ASD, when considering performance in the control task. Thus, our study suggests equal mechanisms underlying reduced emotion recognition in both ASD and ADHD. Focus should be dedicated to identifying this mechanism and develop targeted interventions.