Reflections on my Dissertation: What the Research Taught Me About CPTSD and BPD

When I began my postgraduate Traumatology dissertation, I wanted to explore a question that continues to interest me: Is Complex Post-Traumatic Stress Disorder (CPTSD) equivalent to Borderline Personality Disorder (BPD), and are there differences in the treatment of PTSD, CPTSD and BPD?

My literature review, submitted in January 2022, brought together research exploring diagnostic differences, childhood adversity, attachment, emotional regulation, assessment and treatment.

Working through that literature challenged me to look beyond individual research findings and consider the wider picture. What were researchers agreeing about? Where did findings differ? What remained uncertain? And, importantly, what might these questions mean for therapeutic practice?

In this final article in my series, I reflect on what the research taught me and why these questions continue to matter to me as a Traumatologist.

1. Similarities do not mean that diagnoses are interchangeable

One of the central themes in my dissertation was the relationship between CPTSD and BPD.

The literature I reviewed highlighted areas of overlap, including emotional dysregulation, relationship difficulties and associations with childhood adversity. However, it also supported the importance of recognising differences between trauma-related disorders and BPD.

CPTSD, as defined in ICD-11, includes the core symptoms of PTSD alongside disturbances in self-organisation involving emotional regulation, self-concept and relationships. BPD has its own diagnostic features and may occur with PTSD or CPTSD.

This distinction matters because overlapping symptoms do not necessarily indicate the same underlying difficulties or therapeutic needs.

My review reinforced the importance of careful assessment rather than assuming that one diagnosis explains everything a person experiences.

It also reminded me that diagnostic categories are frameworks for understanding patterns of difficulty. They are not complete descriptions of the individuals who receive them.

2. The importance of childhood experiences, attachment and context

Another theme that stood out was the relationship between childhood adversity and later mental health difficulties.

The literature I examined explored childhood maltreatment, neglect, disrupted attachment relationships and repeated victimisation in relation to CPTSD and BPD.

These experiences can be important when developing an understanding of someone’s history, emotional responses and relationships. However, they should not be treated as a simple explanation for every difficulty or as a guarantee of a particular diagnosis.

Not everyone who experiences adversity develops CPTSD or BPD, and people’s responses to difficult experiences vary.

I became particularly interested in how early experiences might help us understand the different ways emotional dysregulation can present, and how attachment and relational experiences might inform assessment and treatment planning.

This remains an area in which further research is needed.

For therapeutic practice, the message I took from the literature was the importance of exploring relevant history sensitively and considering the wider context of a person’s life, without reducing their current difficulties to their past.

3. Assessment needs to be thorough, thoughtful and individualised

One of the clearest conclusions I reached in my dissertation was the importance of accurate assessment with an appropriately trained professional.

When someone presents with difficulties associated with BPD, it may be important to consider whether PTSD or CPTSD symptoms are also present. Equally, clinicians need to remain open to other explanations, co-occurring conditions and the possibility that a person’s presentation does not fit neatly into one diagnostic category.

The research I reviewed highlighted the development of assessment tools, including the International Trauma Questionnaire (ITQ), alongside the need for greater consistency in assessment procedures.

However, assessment is not simply about administering a questionnaire or matching symptoms to a set of criteria.

It involves listening, asking appropriate questions, understanding the person’s circumstances and considering how different experiences and difficulties may relate to one another.

Exploring trauma history can be sensitive. It needs to be approached with care, appropriate pacing and attention to the person’s sense of safety and choice.

For me, the value of assessment lies in helping us develop a more meaningful understanding of the individual, rather than simply assigning a label.

4. Treatment needs to reflect the person’s presentation

The treatment literature was another important part of my dissertation.

I reviewed research into approaches including Dialectical Behaviour Therapy (DBT), Mentalization-Based Therapy (MBT), trauma-focused interventions and approaches adapted to address overlapping difficulties.

The literature suggested that established treatments for BPD have an important place in the field, while research into CPTSD and co-occurring PTSD and BPD was exploring how existing interventions might be adapted or combined.

What interested me was the question of how a more detailed understanding of diagnostic differences might inform treatment planning going forward.

Someone experiencing predominantly PTSD or CPTSD symptoms may have different priorities from someone whose current difficulties include significant emotional dysregulation, self-harm or relationship instability. Some people may experience a combination of these difficulties.

A diagnosis alone cannot determine the most appropriate treatment. Well informed Clinical decisions need to take account of assessment, the evidence available, the person’s circumstances and their own goals.

My review also highlighted the need for further research into treatment outcomes for people experiencing co-occurring conditions.

The evidence available to me in January 2022 did not justify concluding that one therapy is universally best for everyone with CPTSD or BPD.

Instead, it reinforced the importance of individualised, evidence-informed treatment planning.

5. Research teaches us to recognise uncertainty

Perhaps one of the most valuable aspects of completing the literature review was learning to look critically at the research itself.

It is tempting to read a study’s findings and treat them as definitive. However, research needs to be considered in context.

Studies may use different diagnostic criteria, assessment methods, participant groups and definitions of trauma. Some findings come from small or specific samples, and improvements in one outcome do not necessarily mean improvements in every area of a person’s life.

The literature I reviewed was also developing. Researchers were exploring diagnostic distinctions, proposed developmental frameworks and treatments adapted from existing approaches.

This meant that some questions could not be answered conclusively from the available evidence.

I came to appreciate that acknowledging uncertainty is an important part of responsible research and practice. It allows us to recognise what the evidence supports without claiming more than it can tell us.

It also helps us identify where further research could make a meaningful difference.

6. The questions that remain important

I identified several areas where further investigation could strengthen our understanding of CPTSD and BPD.

These included:

• Diagnostic differentiation: identifying factors that help distinguish CPTSD from BPD while recognising that the conditions may co-occur.
• Assessment: developing clearer and more consistent procedures for assessing trauma-related disorders and personality difficulties.
• Developmental experiences: exploring how childhood adversity, attachment and other factors relate to later presentations without assuming a direct or inevitable pathway.
• Treatment: developing and evaluating interventions that respond to different presentations, including co-occurring conditions.
• Individual differences: examining how wider circumstances, relationships and personal factors may influence experiences and outcomes.

These questions were important in the literature I reviewed, but they should not be taken as a complete account of the research priorities that exist today.

My dissertation was submitted in January 2022. Research has continued since then, and a current assessment of the evidence would need to examine more recent publications.

Nevertheless, the questions I identified helped me appreciate how research develops: one study may clarify an aspect of a problem while opening up new questions that require further exploration.

7. What the research means to me as a Traumatologist

For me, this dissertation was not simply an exercise in comparing two diagnoses.

It was an opportunity to examine how our understanding of trauma, emotional regulation, relationships and diagnostic categories can influence the way we think about therapeutic support.

The literature reinforced the importance of recognising the possible impact of trauma without assuming that trauma explains every difficulty. It highlighted the need to distinguish between overlapping conditions while remaining alert to co-occurrence. It also demonstrated the value of continuing to evaluate treatment approaches rather than assuming that established practices answer every question.

Most importantly, it strengthened my interest in emotional regulation, trauma-informed assessment and individualised treatment planning.

A person’s presentation needs to be understood within the context of their history, relationships, current circumstances, strengths and needs. Their diagnosis may contribute to that understanding, but it should not replace it.

I believe we need to remain willing to ask questions, consider alternative explanations and recognise the limits of our knowledge.

This is not about abandoning diagnostic frameworks or evidence-based practice. It is about using them thoughtfully, with the person rather than the label at the centre of our work.

Bringing the series together

Across this ten-part series, I have explored the development of CPTSD as a diagnosis, its similarities and differences with BPD, the role of childhood adversity and attachment, the challenges of research and assessment, treatment approaches and the questions that remain unanswered.

The literature I reviewed supported the importance of distinguishing CPTSD and BPD rather than treating them as equivalent. It also highlighted the complexity of overlapping symptoms and co-occurring conditions, and the need for accurate assessment and individualised treatment.

There are still important questions to explore, and the evidence continues to develop.

My dissertation was a snapshot of the research available to me at a particular point in time. Returning to its themes through this series has provided an opportunity to reflect on what I learned, explain some of the questions that interested me, and consider why these issues remain relevant to trauma-informed practice, with interested others.

For me, the lasting message is this: research can help us understand patterns, develop better interventions and challenge assumptions, but it must never replace our curiosity about the individual.

People deserve to be understood in all their complexity, with care that is thoughtful, appropriately informed by evidence and responsive to their individual needs.

Thank you for following this series and taking the time to explore these questions with me.

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About this series

This ten-part series draws on my postgraduate Traumatology dissertation literature review, submitted in January 2022. It is intended to share reflections on the research I examined and its relevance to trauma-informed therapeutic practice. It is not a peer-reviewed journal publication or a comprehensive review of research published since 2022.

Lisa Harris
Psychotherapist | Clinical Supervisor | Consultant | Qualified Traumatologist
lisaharris.uk