Trauma, PTSD and complex PTSD
: an analysis of the “Children and Young People’s Mental Health in Northern Ireland Survey”

Student thesis: Doctoral Thesis


The 11th version of the International Classification of Diseases (ICD-11; WHO, 2018) includes posttraumatic stress disorder (PTSD) and complex PTSD (CPTSD) as trauma-related diagnoses. Despite there being extensive investigations of the epidemiology and construct validity of ICD-11 PTSD and CPTSD among adult populations, such research is noticeably lacking within the youth context. This thesis aimed to address this gap through evaluating the integrity of the ICD-11 descriptions of PTSD and CPTSD based on a series of linked studies using data from a large sample of children and adolescents (hereafter referred to as “young people”) from Northern Ireland. Section one of the thesis (Chapters 2 and 3) aimed to evidence the construct validity of PTSD and CPTSD, as well as the determine the prevalence, risk factors, and psychopathological comorbidities associated with both disorders. Section two of the thesis (Chapter 4) aimed to determine the prevalence, patterns, and correlates of childhood trauma. Section three of the thesis (Chapters 5 and 6) sought to broaden the scope from a purely “deficit-based” approach to also considering how benevolent childhood experiences (BCEs) may promote resilience despite negative early life events. Finally, Section four of the thesis (Chapter 7) aimed to identify predictors of PTSD and
CPTSD symptom levels.

Data for the present thesis was derived from the Northern Ireland Youth Wellbeing Prevalence Survey (NI-YWS), the first ever national survey of child and youth mental health in NI. Various advanced analytic techniques were used throughout to address the objectives of the thesis. For Section one of the thesis, a systematic review was first conducted to summarise and synthesize evidence from factor analytic and mixture modelling studies that have investigated the construct validity of ICD-11 PTSD and CPTSD as measured by the International Trauma Questionnaire (ITQ) (Chapter 2). This review highlighted how factor analytic studies consistently identified two symptom structures that reflected the ICD-11 descriptions of PTSD and CPTSD. Moreover, mixture modelling studies consistently identified subgroups of individuals with symptom profiles reflecting the ICD-11 distinction between PTSD and CPTSD. Following this, a type of latent variable modelling technique called factor mixture modelling (FMM) was deployed to evaluate the latent dimensional structure and the conceptual distinctiveness of PTSD and CPTSD as measured by the ITQ-CA among trauma-exposed young people (n = 507) (Chapter 3). Findings supported the ICD-11 conceptualization of PTSD and CPTSD as representing distinct diagnostic constructs among young people. This study also revealed that CPTSD was more prevalent than PTSD among young people, and identified special educational needs (SEN) as representing a novel risk factor of CPTSD and both trauma type and quantity of traumatic exposure as being highly influential in determining a young person’s post-traumatic symptom profile. CPTSD was shown to represent a more comorbid and debilitating condition than PTSD. Section 2 (Chapter 4) of the thesis took a step back from trauma-related psychopathology to understand the epidemiology of childhood trauma exposure among NI youths (n= 1,293). Findings demonstrated that CT exposure was relatively common while latent class analysis (LCA identified three distinct classes with similar patterns of childhood trauma exposure including ‘low-exposure’, ‘moderate-exposure: community-victimization’, and ‘high-exposure: sexual trauma’). Family receiving government benefits and experiences of out-of-home care were found to characterize the most severe class.

Shifting the perspective in Section three of the thesis, findings demonstrated how the majority of NI youth reported having multiple benevolent childhood experiences and that being female, living with both biological parents, having a parent with at least five years post-primary education, and living in areas with lower deprivation were associated with higher levels of BCEs. Moreover, confirmatory factor analytic findings revealed that benevolent childhood experiences represented a distinct range of childhood experiences from adverse childhood experiences, while latent profile analysis results identified different classes of young people with similar average levels of benevolent and adverse childhood experiences. These classes included ‘low BCEs low ACEs’, ‘high BCEs low ACEs’, and ‘high BCEs high ACEs’. Young people in the ‘high BCEs high ACEs’ class were at increased risk of meeting the criteria for probable diagnosis of PTSD, while those in both the ‘low BCEs low ACEs’ and ‘high BCEs high ACEs’ classes were at increased risk of meeting the criteria for probable diagnosis of CPTSD. The final section of the thesis (Chapter 7) adopted a machine learning approach referred to as decision tree modelling and found that trauma and psychopathological comorbidities played a key role in driving PTSD and CPTSD symptom levels. Overall, findings from the present thesis provide support for the integrity of the ICD-11 descriptions of PTSD and CPTSD in the youth context. This thesis provides novel insights into the prevalence, construct validity, risk factors, protective factors, and psychopathological comorbidities associated with PTSD and CPTSD in the youth population of Northern Ireland. Extensive consideration of the clinical, policy, and research implications of the findings are included throughout.
Date of AwardJun 2023
Original languageEnglish
SponsorsDepartment for the Economy
SupervisorJamie Murphy (Supervisor), Mark Shevlin (Supervisor), Orla Mc Bride (Supervisor) & Lisa Bunting (Supervisor)


  • PTSD
  • Complex PTSD
  • ICD-11
  • Young people
  • Trauma
  • Northern Ireland
  • Resilience

Cite this