Pupil Dilation Amplitude to Expressions May Predict CBT Response in Adolescent Social Anxiety

Larger pupil dilation amplitude to happy faces before cognitive behavioral therapy was related to worse treatment response.

Pupil dilation amplitude in response to emotional faces may predict treatment response to cognitive behavioral therapy (CBT) in adolescents with social anxiety disorder (SAD), according to study data published in the Journal of Anxiety Disorders.

Participants were recruited from an existing clinical trial that examined the impact of CBT in adolescents (age 13 to 17) with SAD. Healthy adolescents without SAD were randomly selected from the Swedish population register and invited to participate in the study. To provide pupil and gaze data, participants were presented with 20 still images of facial expressions; 50% displayed an angry expression and 50% a happy expression. An eye tracker module was used to capture pupil size and gaze coordinates on the stimulus image. Following the initial data collection, participants with SAD underwent a 12-week CBT program. After 12 weeks, the SAD group again underwent pupil assessment. Individuals with SAD also completed a series of clinician- and self-rated psychiatric symptom scales at baseline and post-treatment, including the Social Phobia and Anxiety Inventory for Children.

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The final study cohort comprised 26 individuals with SAD and 23 healthy controls, of whom 22 and 20 were girls, respectively. At baseline, larger pupil dilation amplitude was observed for angry faces compared with happy faces in the SAD (P =.007) and control groups (P =.004). The SAD and control groups did not differ in overall pupil dilation amplitude; however, the time course of pupil dilation was slightly longer in individuals with SAD compared with controls  In individuals with SAD, pupil dilation amplitude at baseline predicted higher symptom severity post-treatment per both clinician (P =.032) and patient ratings (P =.044). Pupil dilation amplitude in response to happy faces predicted both clinician and patient-rated symptom severity following treatment (P =.002) after adjusting for baseline symptom level. However, the same effect was not observed for angry faces. Thus, investigators concluded that “hyperarousal” during the processing of happy expressions was a risk factor for poorer CBT response.

While these data suggest that pupil dilation metrics may be a useful predictor of treatment response, further research with a larger sample size is necessary to explore the mechanisms behind differential pupil dilation in SAD.  


Kleberg JL, Hanqvist C, Serlachius E, Högström J. Pupil dilation to emotional expressions in adolescent social anxiety disorder is related to treatment outcome [published online April 24, 2019]. J Anxiety Disord. doi:10.1016/j.janxdis.2019.04.006