CPTSD and BPD: Exploring the Research Behind My Traumatology Dissertation

Introducing a research series exploring Complex Post-Traumatic Stress Disorder, Borderline Personality Disorder, trauma-informed assessment and the implications for therapeutic practice.

Why I undertook this research

In January 2022, I submitted a literature review exploring Complex Post-Traumatic Stress Disorder (CPTSD) and Borderline Personality Disorder (BPD) as part of the dissertation requirements for my postgraduate qualification in Traumatology.

I am now revisiting that academic work and adapting it into a series of articles for my professional website. My intention is to make the research more accessible, share the questions it raised and explore its implications for trauma-informed psychological practice.

This series is based on my own academic work. The original literature review examined published research available at the time, critically considering the evidence, the differences and similarities between diagnostic presentations, and the implications for assessment and treatment.

It is important to clarify that my dissertation was submitted to meet the academic requirements of my postgraduate qualification; it was not a peer-reviewed journal publication. These articles will preserve the substance of that original work while making it more accessible to practitioners and others interested in trauma. Where appropriate, I will distinguish the original research review from subsequent developments in the evidence base.

Why CPTSD and BPD?

One of the central questions explored in my dissertation was the relationship between CPTSD and BPD. Both diagnostic presentations can involve significant emotional distress, difficulties in relationships and challenges with regulating emotions. This can create complexity when clinicians are considering how best to understand an individual’s experiences and needs.

Research has explored whether CPTSD and BPD can be distinguished from one another, including studies examining patterns of symptoms and the characteristics associated with each diagnosis. For example, Cloitre and colleagues (2014) investigated whether symptom patterns among women with histories of childhood abuse supported distinctions between PTSD, CPTSD and BPD. Subsequent research has continued to examine the similarities and differences between these presentations.

This is not simply a question of terminology. How a person’s difficulties are understood can influence assessment, formulation, therapeutic conversations and decisions about support.

The aim is not to assume that one diagnosis explains every aspect of a person’s experience, nor to suggest that the two presentations can never coexist. Rather, it is to consider what the research can tell us about their similarities, differences and complexities.

Looking beyond diagnostic labels

A trauma-informed perspective requires us to remain curious about the experiences and circumstances that may have shaped a person’s life.

The literature considered in my dissertation explored themes including trauma exposure, childhood adversity, attachment, emotional regulation and difficulties in adult relationships. These areas are relevant to understanding both CPTSD and BPD, although their presence does not automatically indicate either diagnosis.

It is important not to assume that everyone who has experienced trauma will develop the same difficulties, or that a particular childhood experience inevitably leads to a specific adult presentation. People respond to adversity in different ways, and their experiences need to be understood within their wider personal, social and developmental contexts.

For practitioners, this means balancing knowledge of diagnostic criteria with careful listening, thoughtful assessment and an appreciation of individual complexity.

What did the research reveal — and what remained uncertain?

Reviewing the literature highlighted the importance of examining not only the findings of individual studies but also how those findings were reached.

Research can differ in its diagnostic criteria, assessment instruments, participant groups and methods of analysis. These differences matter when comparing findings or considering how far conclusions can be applied to other populations and clinical settings.

For example, a study involving people recruited from a specialist clinical service may not tell us exactly the same thing as research conducted with a general population sample. Similarly, findings from one group of participants cannot automatically be generalised to everyone who experiences CPTSD or BPD.

Critical engagement with research therefore involves asking questions: What was studied? How were the diagnoses or symptoms assessed? Who took part? What conclusions are supported by the findings, and where should caution remain?

These questions were central to my engagement with the literature and remain important when considering how research informs therapeutic practice.

What will this research series explore?

Over the coming articles, I will revisit key themes from my dissertation, including:

• The development of PTSD and CPTSD as diagnostic concepts.
• The similarities and differences between CPTSD and BPD.
• The relationship between trauma, childhood adversity, attachment and emotional regulation.
• How researchers investigate diagnostic differences and symptom patterns.
• The strengths and limitations of the available evidence.
• Implications for clinical assessment, formulation and therapeutic practice.
• Questions that remain unanswered and areas where further research is needed.

The series will also provide an opportunity to reflect on how academic research can inform practice without replacing clinical judgement or the need to understand each person as an individual.

Where I discuss developments that occurred after my original dissertation was submitted, I will make that distinction clear so that readers can see what belongs to the original review and what represents later evidence or reflection.

A note about the research and references

The dissertation was my own academic literature review, bringing together and critically considering published research on CPTSD and BPD. The original studies remain the work of their respective authors, and I will reference those sources throughout this series.

The references at the end of each article will relate to the research discussed in that particular piece, rather than reproducing the entire bibliography of my dissertation every time.

My intention is to support thoughtful engagement with the evidence and to make it easier for readers who wish to explore the original research in greater depth.

Continuing the conversation

This series is intended for therapists, clinical supervisors, other practitioners and interested others who want to think more deeply about complex trauma, diagnosis and therapeutic understanding.

I hope it will offer an accessible way into the literature while retaining the critical reflection that academic research requires. Above all, I want to encourage curiosity: about what we know, what we do not yet know, and how we can use evidence responsibly in our work with people.

This article introduces a series based on my postgraduate Traumatology dissertation. The following articles will explore the research in greater depth, one theme at a time.

Lisa Harris
Psychotherapist | Clinical Supervisor | Consultant | Qualified Traumatologist

lisaharris.uk

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References

Cloitre, M., Garvert, D. W., Weiss, B., Carlson, E. B. and Bryant, R. A. (2014). Distinguishing PTSD, complex PTSD, and borderline personality disorder: A latent class analysis. European Journal of Psychotraumatology, 5, 25097. https://doi.org/10.3402/ejpt.v5.25097

Frost, R., Hyland, P., Shevlin, M. and Murphy, J. (2018). Distinguishing Complex PTSD from Borderline Personality Disorder among individuals with a history of sexual trauma: A latent class analysis. European Journal of Trauma & Dissociation, 4, 100080. https://doi.org/10.1016/j.ejtd.2018.08.004

Jowett, S., Karatzias, T., Shevlin, M. and Albert, I. (2020). Differentiating symptom profiles of ICD-11 PTSD, complex PTSD, and borderline personality disorder: A latent class analysis in a multiply traumatized sample. Personality Disorders: Theory, Research, and Treatment, 11, 36–45. https://doi.org/10.1037/per0000346