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

Abstract

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.

Keywords:

• Emotional regulation
• eye tracking
• parasympathetic nervous system
• posttraumatic stress disorder
• pupillometry

Acknowledgments

We thank the mothers and their children for participating in the study and the study staff, the clinical and administrative staff of the Western Cape Government Health Department at Paarl Hospital and at the clinics for support of the study. We acknowledge Gerdia Harvey for her help with data collection.

Statement of interest

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The remainder of the authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

The study was funded by the Bill and Melinda Gates Foundation [OPP 1017641]. Additional support for HJZ and DJS was provided by the Medical Research Council of South Africa. DJS has received research grants and/or honoraria from Lundbeck and Servier. This research was also supported by a joint project grant from the Academy of Finland and National Research Foundation, South Africa [# 2501271617]. The fifth author received a grant from the Emil Aaltonen Foundation, Finland.