Date of Award
Fall 2021
Document Type
Dissertation
Degree Name
Master of Science (MS)
Department
Psychology
First Advisor
Fitzgerald, Jacklynn
Second Advisor
deRoon Cassini, Terry A.
Third Advisor
Torres, Lucas
Abstract
Exposure to a traumatic event is a significant predictor for the development of posttraumatic stress disorder (PTSD) and depression. Identification of specific risk factors for PTSD and depression after trauma exposure has been challenging due to comorbid and heterogeneous presentations of these conditions. Pre-existing research demonstrates reduced cortisol response (hypocortisolism) in chronic PTSD and an exaggerated cortisol response (hypercortisolism) in depression. The current longitudinal study examined cortisol response following a traumatic injury as a potential biomarker for deciphering specific risk for PTSD, depression, and PTSD depression comorbidity. Saliva samples for cortisol assay (post-injury cortisol) were collected from 172 trauma survivors during post-trauma hospitalization. Six months after the injury these participants completed the CAPS-5 measure for PTSD. Symptom severity scores for PTSD and dysphoria (akin to depression) were calculated from CAPS-5 measure following the two-factor PTSD model. Cluster analytic models revealed four distinct subgroups of individuals in the sample: Resilient (minimal PTSD and dysphoria symptoms; 57%), Dysphoric (mild symptoms of dysphoria; 15%), High comorbid (high symptoms of PTSD and dysphoria; 21%) and Severe comorbid (severe symptoms of PTSD and dysphoria; 7%). The Severe comorbid subgroup was associated with significantly lower post-injury cortisol compared to the Resilient and Dysphoric subgroups, but not from the High comorbid subgroup. Individuals in the Dysphoria subgroup exhibited significantly higher postinjury cortisol compared to all the other subgroups. The High and Severe comorbid subgroups were only differentiated by pre-injury psychiatric diagnosis with greater premorbid psychiatric history in the Severe group. Findings identify the pertinent role of post-trauma cortisol as an early risk-marker for the development of depression and severe comorbid PTSD-depression symptomology in trauma survivors. Implications are discussed.