1. Heterogeneity in PTSD symptomatology
My first line of research examines diversity in symptom presentations and profiles which differentially influence the course of PTSD, diagnostic estimates, comorbidity patterns, response to treatment, and the specificity/non-specificity of PTSD's different symptom clusters. Utilizing factor analysis, a methodology that assesses symptom heterogeneity and identifies the optimal PTSD symptom cluster groupings, my research demonstrates DSM-IV PTSD symptoms are best represented by 4 or 5 symptom clusters, rather than the traditional 3 DSM-IV clusters. Such results provide support for the revised DSM-5 4-factor structure for PTSD. Using DSM-5 PTSD criteria, my research also supports a 7-factor Hybrid model separating PTSD's negative alterations in mood and cognitions cluster into positive and negative affect factors, and PTSD's arousal cluster into externalizing behaviors, anxious arousal, and dysphoric arousal factors, while retaining PTSD's intrusion and avoidance clusters. Relevant to transdiagnostic protocols, my research has shown that PTSD's numbing/dysphoria symptoms are non-specific to PTSD, accounting for PTSD's relation with other distress disorders. Identification of the optimal symptom cluster representation comprised of PTSD-specific symptoms is critical for a valid and reliable diagnostic assessment, and to enhance effective interventions.
My work also identifies subgroups of individuals with differing symptom type and/or severity. Using latent class/profile analysis that account for heterogeneity in the population, my research has supported the construct validity of 3 or 4 subgroups of individuals that mainly differ in symptom severity. These subgroups have differential relations with psychopathology and demographic variables, providing the opportunity for researchers (and ultimately clinicians) to address common risk factors and mental health outcomes within groups. Further, I have also found support for a depression subtype of PTSD; members of this subgroup have higher PTSD and depression severity compared to other subgroups. Results of such studies provide evidence for PTSD and depression as distress disorders representing part of a common reaction to trauma, a largely debated topic in the field. This work highlights the importance of acknowledging and integrating the moderating influence of PTSD-based subgroups in research and clinical work.
2. Heterogeneity in traumatic experiences
My second line of research examines the nature and count of traumatic experiences in relation to psychopathology, and the construct validity of subgroups of individuals based on their pattern of endorsed traumatic experiences. Not all traumatic experiences are equal in potency and effect, which could possibly influence the choice and outcomes of intervention. The most prominent manuscript in this area includes a published systematic review on lifespan polytraumatization patterns, which supports the importance of considering patterns and types of multiple traumatic experiences in relation to different post-trauma mental health outcomes. I have additionally examined the relation of different types of military-related traumatic experiences to psychopathology (Litz et al., 2018), the nature and relation of polytraumatization patterns to post-trauma mental health (Contractor, et al., 2018), and the relation between the count of traumatic experiences and psychopathology (Gerber et al., 2018).
3. Mechanisms of PTSD's comorbidity with depression
My third line of research investigates the specific symptom dimensions and transdiagnostic constructs driving the comorbid relationship between PTSD and mood disorders; these mechanisms are rarely investigated despite PTSD being most commonly comorbid with mood disorders. I have found that primarily somatic rather than non-somatic depression may be accounting for depression's relation with PTSD. Consistently, my research indicates that PTSD's dysphoria symptoms (overlapping with some mood/cognition symptoms in DSM-5) may account for PTSD's comorbidity with depression. Beyond implications for transdiagnostic assessments and interventions, my research adds to the debate on non-specific PTSD symptoms responsible for PTSD's comorbidity with distress disorders, and on what constitutes the primary and essential symptoms of PTSD to be retained in diagnostic manuals.
This line of research also examines the role of transdiagnostic constructs that may account for PTSD's relation with depression. A co-authored published study indicates that repetitive (intrusive and involuntary thoughts) and anticipatory rumination (perseveration over future events) moderate the relationship between depression and PTSD symptoms. Thus, rumination seems to be an influencing factor in the PTSD-depression relationship; current trauma-focused interventions have not adequately addressed this factor. Another transdiagnostic factor underlying the relations between PTSD and depression is difficulties retrieving specific positive memories; such difficulties are common to PTSD and depression. One of my manuscripts discusses the role and significance in addressing positive memories in PTSD treatment, drawing from similar interventions used to treat depression.
4. Mechanisms of PTSD's comorbidity with impulsive risky behaviors
My fourth line of research investigates specific PTSD symptom dimensions and transdiagnostic constructs (e.g., impulsivity facets) driving the relation between PTSD and risky behaviors, such as substance use. Findings indicate that compared to other impulsivity facets, a tendency to act impulsively when experiencing intense negative affect strongly relates to PTSD severity and mediates the relation between PTSD severity and addictive behaviors (i.e., smartphone use). My research has indicated the possible functional role of impulsivity in coping with PTSD-related anger, further highlighting an emotional regulation function of impulsive behaviors in relation to PTSD severity. Thus, my research supports targeting impulsivity, particularly emotional regulation of negative affect in trauma treatment. Parallel to this research endeavor, I am currently developing and validating a brief and yet clinically sensitive measure of post-trauma risky behaviors aligned with DSM-5 "risky behaviors" criteria.
Substance use as a potential risky behavior is highly comorbid with PTSD. My research examining PTSD-substance use relations demonstrates that PTSD's dysphoria moderates the relations between alcohol use and PTSD's intrusion symptoms. Beyond supporting the self-medication theory, such results have treatment implications; primarily they inform specific treatment targets (e.g., dysphoria) in comorbid PTSD-substance use treatment. Further, results again highlight the distress-laden nature of PTSD's dysphoria. I am in the process of collecting longitudinal data from a treatment-seeking community sample to investigate the longitudinal relations between PTSD and alcohol use.
5. Cultural influences on PTSD's symptomatology
My fifth line of research examines the intersection between cultural factors and PTSD symptomatology. I have highlighted the relations between culture and trauma through peer-reviewed publications, as well as through the International Society for Traumatic Stress Studies newsletter articles. To assess the influence of cultural factors on PTSD's symptomatology, I examined latent-level PTSD-distress relations in children/adolescents exposed to terrorist attacks in India. Results indicated that PTSD's dysphoria factor did not represent PTSD's "non-specific" distress among Indian youth. Surprisingly, PTSD's dysphoria symptoms related to depressive rather than somatic distress, consistent with Western literature. This study was the first attempt to analyze PTSD's factor structure in this culture, and highlighted the need to assess comorbid depression following trauma exposure in India. Currently, I am examining military mental health in India through a UNT funded study. Results of the study will highlight patterns of traumatic experiences and mental health in this population, and can possibly inform Indian mental health initiatives and reforms. Further, I also examine the stability of the construct of PTSD across cultural groups; this is a statistical and conceptual requirement before examining any between-group symptomatic differences. My published study indicated that the PTSD construct is stable across racial and ethnic groups in the US, laying the foundation to investigate other clinically relevant cultural factors beyond racial/ethnic status.