Date of Award

December 2023

Degree Type

Thesis

Degree Name

Master of Science

Department

Psychology

First Advisor

Christine L Larson

Committee Members

Jacklynn M Fitzgerald, Cecilia J Hillard

Keywords

Endocannabinoid System, Post-Traumatic Stress Symptoms, Resting State Functional Connectivity, Trauma

Abstract

Introduction: Traumatic injury increases risk for long-term adverse outcomes such as the development of post-traumatic stress disorder (PTSD). Research has found that risk for the development of PTSD after such an injury varies depending on individuals’ race/ethnic group and sex. Although prior work has explored relationships between injury and PTSD in these groups utilizing imaging paradigms (e.g., resting state functional connectivity) and biological paradigms (e.g., the endocannabinoid system), the relationship between these factors has been understudied. The present study explored the potential moderating effect circulating endocannabinoids may have on the relationship between resting state functional connectivity and post traumatic stress symptoms (PTSS) in a population who has recently been traumatically injured. We also aimed to explore sex and racial group differences in these models.Method: Using pre-collected data (n = 105) we bifurcated our sample into four groups based on individuals’ race and sex: Black females (n = 44), White females (n = 17), Black males (n = 34), and White males (n = 10). We then ran three analyses utilizing data collected 2 weeks after an injury occurred. First, we ran a correlation between PTSS, concentrations of N-Arachidonoylethanolamine (AEA) and 2-arachindonoylglycerol (2-AG), connectivity within the default mode network (DMN), connectivity within the salience network (SN), and age. Next, we ran general linear models, with age as a covariate, exploring the relationship between DMN connectivity and PTSS as well as SN connectivity and PTSS. Finally, we ran moderation models examining if AEA or 2-AG moderated the relationship seen between DMN (or SN) connectivity and PTSS with age again included as a covariate. Results: We found correlations that were unique to each group. Specifically, in Black females we found a significant positive correlation between DMN connectivity and 2-AG (r = 0.34), between PTSS and AEA (r = 0.33), and between 2-AG and age (r = 0.33). In White females, we found a significant negative correlation between SN connectivity and PTSS (r = -0.52). In Black males, we found a significant correlation between DMN connectivity and PTSS (r = 0.37) and DMN connectivity and AEA (r = 0.41). There were no significant correlations found in White males. Next, in our general linear models, we found a significant positive relationship between DMN connectivity and PTSS in Black males (t = 2.21, p = 0.03). Finally, we found that AEA negatively moderated the relationship between DMN and PTSS (t = -2.46, p = 0.03) and 2-AG positively moderated the relationship between SN connectivity and PTSS (t = 3.02, p < .01). Discussion: Our findings suggest that there may be unique associations between the endocannabinoid system, imaging, and PTSS in individuals when considering race and sex. This could in part be due to variable experiences of prior traumas (e.g., females and racial/ethnic minorities are more likely to have experienced prior trauma and go on to develop PTSD). Some of our findings in our Black/African American participants also mimic findings in previous work exploring experiences of racism with imaging data. Future work should further explore group differences in larger samples as well as bring in other relevant measures (e.g., prior trauma, experiences of racism, and experiences of minority stress).

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