Investigating pupillometry to detect emotional regulation difficulties in post-traumatic stress disorder

Objective Individuals with posttraumatic stress disorder (PTSD) have been found to exhibit emotional regulation difficulties. However, the specific neural mechanisms that underlie these difficulties remain understudied. This study aimed to use pupillometry as an index function of parasympathetic nervous system activation, to investigate the mechanisms underlying emotional regulation difficulties in individuals with PTSD. Method A total of 87 trauma-exposed mothers (34 with PTSD and 53 non-PTSD controls) completed an eye tracking assessment in which pupillary dilation in response to emotionally valenced stimuli was measured. The participants also completed two self-report measures of emotional regulation, namely the Difficulties in Emotional Regulation Scale and the Emotional Regulations Questionnaire. Linear mixed-effect modelling was used to assess potential group differences. Results The PTSD group exhibited increased pupillary dilation to positively valenced stimuli compared to the non-PTSD group. However, no significant associations between the self-report measures and pupillary response to emotionally valenced stimuli were found. Conclusion Increased pupillary dilation in PTSD may reflect impaired parasympathetic nervous system processes. The lack of association of these measures with self-reported emotion regulation may suggest reporting biases. Larger studies with more generalised populations are required to consolidate these preliminary findings.