Exploring the utility of pupillometry as a biomarker for relationships between early life stress, emotion regulation, and cognition
While the negative effects of early life stress (ELS) are well-documented, non-invasive biomarkers that can be used to aid early detection of vulnerable groups and overcome some of the limitations of self-report tools are not readily available. Recently, pupillometry has been recognised as a novel, non-invasive approach to identify potential abnormalities in cognitive and emotional functioning linked to ELS and stress-induced alterations in the locus coeruleus-norepinephrine (LC-NE) pathway. However, to date, no studies have investigated the relationship between pupil dilation (PD) and blink rate (EBR), and ELS. In this study, we therefore explored the utility of pupillometry for distinguishing between groups of participants with histories of high versus low ELS. We investigated to what extent ELS predicts PD during cognitive processing in adulthood and the potential roles of cognitive ability, mood, and emotion regulation style in these relationships. Participants (N = 94) completed the Traumatic Antecedents Questionnaire, Emotion Regulation Questionnaire, and Beck Depression and Anxiety Inventories. PD in response to a challenging cognitive task was used as a proxy for active coping or cognitive effort. Heart rate variability served as a physiological biomarker of emotional regulation. A battery of cognitive tests were utilised to assess core domains of cognition. We hypothesised that PD responses would differ between ELS groups under the baseline and cognitive conditions and depression would be associated with a reduced EBR. Our results indicated that the high ELS group had more depressive symptoms, lower levels of dopamine, and poorer cognitive outcomes, irrespective of education and age. There was evidence to suggest that emotional disturbance may be linked to alterations in the LC-NE pathway as a more rapid decline in pupil size was observed in participants with more depressive symptoms during the memory recall task condition. However, contrary to our hypothesis, there were no anomalies in PD directly related to ELS. While self-report tools that assess mood disturbances appear to offer more predictive power, the clinical utility of pupillometry as a biomarker of the effects of ELS is still under debate due to methodological limitations.
Networked Digital Library of Theses and Dissertations