CPTSD and BPD: Assessment, Formulation and the Individual Behind the Diagnosis

Why understanding the person matters as much as understanding the symptoms

How do we move from identifying symptoms to developing an understanding of the person experiencing them?

This was an important question within my postgraduate Traumatology dissertation. Although the literature I reviewed explored similarities and differences between Complex Post-Traumatic Stress Disorder (CPTSD) and Borderline Personality Disorder (BPD), it also highlighted the importance of careful assessment and individualised treatment planning.

When symptoms overlap, it can be tempting to focus on diagnostic categories alone. Yet understanding a person’s history, current difficulties, relationships and ways of managing distress may provide a much richer picture.

In this seventh article in my research series, I explore what the literature suggested about assessment and formulation, and why these processes matter within trauma-informed therapeutic practice.

Why does assessment matter?

A diagnosis can provide a useful framework for understanding psychological difficulties, but it does not capture the entirety of someone’s experience.

CPTSD and BPD can share features involving emotional regulation, self-perception and relationships. However, research discussed in my dissertation suggested that they can also present with different patterns of symptoms.

This creates an important clinical question: how can practitioners recognise overlapping features while remaining attentive to the distinctions that may be relevant to treatment?

My review highlighted the value of assessing for CPTSD symptoms when someone presents with difficulties associated with BPD. This does not mean assuming that trauma explains every presentation, or that one diagnosis should replace another. It means remaining open to the possibility that more than one formulation may need to be considered.

Looking beyond a symptom checklist

The literature reviewed for my dissertation encouraged consideration of several aspects of a person’s experience, including:

• Trauma history: where relevant and appropriate, exploring experiences of abuse, neglect, repeated victimisation or other significant adversity.
• Attachment and relationships: considering patterns of trust, closeness, relational detachment and fear of abandonment.
• Emotional regulation: exploring how distress develops, how it is experienced and the ways the person responds to it.
• Self-perception: considering persistent shame, negative beliefs about oneself, identity difficulties and feelings of worthlessness.
• Current circumstances: recognising the influence of relationships, family experiences, socioeconomic factors and other contextual influences.

These areas are not a diagnostic checklist, and none should be interpreted in isolation. Their value lies in helping develop a more complete understanding of the person’s presentation.

Understanding the chronology of experience

One of the themes in my dissertation was the potential value of understanding the chronology of a person’s experiences.

Exploring when difficulties began, how they developed and how they relate to significant experiences may help clinicians build a clearer formulation.

For example, it may be useful to understand whether someone experiences persistent feelings of threat, avoidance or relational detachment, alongside difficulties with self-worth and emotional regulation. It may also be important to explore patterns of intense emotional responses, fear of abandonment, impulsivity or instability in relationships.

The purpose is not to retrospectively assign a diagnosis to every experience. Rather, it is to understand how the person’s difficulties fit together and whether the proposed formulation adequately accounts for what they are experiencing now.

A person’s history can offer valuable context, but it cannot establish a diagnosis by itself.

Assessment needs to be handled sensitively

My literature review also acknowledged that exploring traumatic experiences can be difficult.

Detailed questions about childhood abuse, neglect or repeated victimisation may evoke distress, particularly if the person has not previously discussed these experiences in a therapeutic setting.

A trauma-informed approach therefore needs to consider not only what information might be relevant, but also how and when it is explored.

This includes attending to safety, pacing, consent and the person’s readiness to discuss difficult material. Assessment should not become an exercise in obtaining a complete trauma history at the expense of the therapeutic relationship or the person’s emotional well-being.

Sometimes it may be appropriate to gather information gradually, returning to particular areas when the person feels sufficiently supported. The aim is to develop understanding collaboratively, without pressure or judgement.

What role do assessment tools play?

The research considered in my dissertation discussed the development of tools designed to support the assessment of PTSD and CPTSD.

The International Trauma Questionnaire (ITQ), for example, was developed to assess the ICD-11 symptoms of PTSD and CPTSD. Other structured interviews and questionnaires can support the assessment of personality disorder features.

These tools can provide useful information, but they have limitations. A screening measure is not a substitute for a comprehensive clinical assessment, and results need to be interpreted in context.

Where CPTSD and BPD are both being considered, it is particularly important to avoid relying on a single questionnaire or isolated symptom to settle a complex diagnostic question.

Assessment tools are best understood as part of a wider process that includes clinical judgement, the person’s account of their experiences and consideration of alternative or co-occurring explanations.

From assessment to formulation

Assessment gathers information. Formulation helps make sense of it.

A formulation brings together the person’s experiences, current difficulties, strengths, coping strategies and circumstances to develop an individualised understanding of what may be contributing to their distress.

In the context of CPTSD and BPD, this may involve considering the relationship between trauma exposure, emotional regulation, self-perception and interpersonal difficulties, while remaining open to other relevant factors.

A formulation should not be a fixed explanation imposed on someone. It is a working understanding that can be explored, discussed and revised as new information emerges.

This distinction matters because two people with the same diagnosis may have very different histories, priorities and support needs.

Equally, two people with similar experiences may develop different patterns of difficulty. A formulation allows space for these differences rather than assuming that a diagnostic label explains everything.

Why does formulation matter for treatment?

The literature reviewed for my dissertation suggested that accurate assessment could help inform more appropriate, individualised treatment planning.

Different presentations may require different therapeutic priorities. For example, treatment planning may need to consider trauma-related symptoms, difficulties with emotional regulation, relationship patterns, self-harm risk or other significant concerns.

Where CPTSD and BPD co-occur, the picture may be more complex still. A clinician may need to consider how different difficulties interact and how treatment can respond to them in a coordinated way.

This does not mean that a diagnosis automatically determines a particular therapy. Decisions about treatment need to take account of the individual’s presentation, preferences, goals, circumstances, risks and the available evidence.

The central point is that treatment should be informed by a thoughtful understanding of the person, rather than selected solely on the basis of a label.

A trauma-informed approach without assumptions

Trauma-informed practice requires sensitivity to the possible effects of trauma, but it also requires care not to assume that every difficulty is trauma-related.

Not everyone with BPD has a history of childhood trauma, and not everyone who experiences trauma develops CPTSD or BPD.

A person’s experiences should be taken seriously without being forced into a particular explanatory framework.

For me, this is where careful assessment and formulation become especially important. They provide an opportunity to explore the individual’s experience, recognise uncertainty and develop a shared understanding that can guide appropriate support.

The aim is neither to reduce someone to a diagnosis nor to explain everything through trauma. It is to remain attentive to the whole person.

Reflections from my Traumatology dissertation

When I submitted my literature review in January 2022, I was particularly interested in whether a clearer understanding of CPTSD and BPD could support more accurate assessment and more individualised therapeutic planning.

The literature suggested that diagnostic distinctions could be clinically relevant, while also highlighting the overlap between symptoms and the limitations of the available evidence.

For me, one of the most important conclusions was the need to combine research knowledge with careful clinical thinking. Understanding diagnostic criteria matters, but so does understanding how a person’s difficulties developed, how they experience them and what they need from therapy.

This article reflects the literature considered in my original dissertation rather than a comprehensive review of research published since 2022.

In the next article, I will explore the treatment approaches discussed in my review, including what the literature suggested about adapting interventions when PTSD, CPTSD and BPD symptoms overlap.

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

References

Cloitre, M., et al. (2014). Distinguishing PTSD, Complex PTSD, and Borderline Personality Disorder: A latent class analysis. European Journal of Psychotraumatology, 5(1). https://doi.org/10.3402/ejpt.v5.25097

Ford, J. D., & Courtois, C. A. (2014). Complex PTSD, affect dysregulation, and borderline personality disorder. Borderline Personality Disorder and Emotion Dysregulation, 1, 9. https://doi.org/10.1186/2051-6673-1-9

World Health Organization. (2018). International Classification of Diseases, 11th Revision (ICD-11).