What Does the Research Say About Treatment? Exploring CPTSD and BPD

When I began exploring the relationship between Complex Post-Traumatic Stress Disorder (CPTSD) and Borderline Personality Disorder (BPD) for my postgraduate Traumatology dissertation, one question became increasingly important to me: if these conditions can overlap, how do we ensure that people receive the most appropriate therapeutic support?

Understanding the similarities and differences between diagnoses is important, but it is only part of the picture. We also need to consider what the research tells us about treatment, where the evidence remains uncertain, and why an individualised approach matters.

In this eighth article in my series exploring the research behind my dissertation, I revisit some of the treatment literature I examined in my January 2022 review.

This is a reflection on that literature rather than a comprehensive review of all the research available today.

Why does the distinction between CPTSD and BPD matter for treatment?

CPTSD and BPD can share features such as difficulties with emotional regulation, relationship challenges and distress associated with earlier experiences. However, overlapping symptoms do not necessarily mean that the underlying difficulties, treatment priorities or therapeutic needs are identical.

CPTSD includes the core symptoms of PTSD alongside difficulties with self-organisation, including emotional regulation, negative self-concept and relationships. BPD has its own diagnostic features and can present in different ways.

Some people may meet the criteria for one condition, while others may experience both or have additional mental health needs.

This matters because treatment should not be selected simply by matching a diagnosis to a particular therapy. It requires consideration of the person’s presentation, history, current difficulties, strengths, circumstances and goals.

In my dissertation, the importance of accurate assessment and personalised treatment planning emerged as a recurring theme.

Dialectical Behaviour Therapy (DBT)

Dialectical Behaviour Therapy, or DBT, was one of the prominent approaches identified in the BPD treatment literature I reviewed.

DBT was developed to support people experiencing significant emotional dysregulation and difficulties that can include self-harm and suicidal behaviours. It commonly focuses on developing skills in areas such as emotional regulation, distress tolerance, mindfulness and interpersonal effectiveness.

Storebø (2020), in a review of 75 clinical trials examining psychotherapy for BPD, identified 16 different treatment approaches. DBT and Mentalization-Based Therapy (MBT) were among the most prominent.

This illustrates the breadth of the treatment literature, while also highlighting the importance of looking beyond a therapy’s prominence to understand what outcomes have actually been demonstrated.

The findings I recorded from Neacsiu (2014) suggested that DBT could help with some difficulties, including avoidance and anger.

The broader point remains important: a treatment may help with some aspects of a person’s presentation without necessarily resolving every difficulty they experience.

Mentalization-Based Therapy (MBT)

Mentalization-Based Therapy, or MBT, was another prominent approach in the BPD treatment literature.

Mentalization broadly refers to our capacity to make sense of our own behaviour and that of other people in terms of thoughts, feelings, intentions and underlying mental states. When distress is high, this capacity can become more difficult, potentially affecting relationships and how situations are interpreted.

MBT aims to strengthen this capacity and support more reflective ways of understanding oneself and others.

The literature I reviewed also raised questions about the extent to which MBT demonstrated superiority over other forms of psychotherapy for particular outcomes, including anxiety, depression, social adjustment and relationship functioning.

I would not interpret this as evidence that MBT is ineffective. Rather, it illustrates why treatment research needs to be considered carefully: the question is not simply whether a therapy works, but for whom, for which difficulties, compared with what alternative, and over what period.

What happens when PTSD and BPD occur together?

One of the most interesting areas in my dissertation was the research exploring treatments adapted to address both BPD-related difficulties and post-traumatic stress symptoms.

This raises an important clinical question. If someone experiences significant emotional dysregulation alongside PTSD symptoms, is it sufficient to focus on one set of difficulties, or might treatment need to address both?

Combining DBT with Prolonged Exposure

Harned’s research explored an adaptation of DBT incorporating Prolonged Exposure (PE) for women experiencing both BPD and PTSD.

Prolonged Exposure is a trauma-focused treatment that involves carefully supported engagement with trauma-related memories and situations that have become associated with fear or avoidance. It requires appropriate clinical assessment, preparation and monitoring.

There was a pilot study in which DBT was combined with PE over approximately one year. The findings recorded included substantial improvement in PTSD symptoms, alongside reductions in self-injury and suicide attempts. An 80% PTSD remission figure was reported.

However, the same study indicated that the combined approach did not demonstrate an advantage over DBT alone on measures of interpersonal problems or quality of life.

These distinctions matter. The findings were promising, but a pilot study involving a particular group of participants cannot establish that the same outcomes will occur for everyone. Nor does improvement in one area necessarily mean that every aspect of a person’s life will improve to the same extent.

The research also highlighted the importance of trauma processing itself. My review noted PTSD symptoms improved when trauma processing began, rather than assuming that stabilisation alone would necessarily resolve them.

This raises questions about how clinicians can balance safety, readiness, emotional regulation and trauma-focused work in an appropriately paced treatment plan.

DBT-PTSD and other trauma-focused approaches

I also considered research into DBT-PTSD, an approach developed for people experiencing PTSD alongside significant emotional and behavioural difficulties associated with childhood trauma.

The literature I examined compared this approach with other PTSD treatments, including Cognitive Processing Therapy (CPT) and Acceptance and Commitment Therapy (ACT).

The findings recorded suggested that the treatments reduced PTSD symptoms, while DBT-PTSD was associated with improvements in additional areas, including BPD symptoms, depression and dissociation. The notes also reported lower dropout in the DBT-PTSD group.

These findings need to be interpreted in the context of the particular studies, participants and treatment protocols involved.

Nevertheless, the research illustrates an important direction in treatment development: rather than treating trauma-related symptoms and emotional dysregulation as entirely separate problems, researchers have explored approaches designed to address their interaction.

Trauma-focused treatments for CPTSD

The literature I reviewed also considered whether treatments developed for PTSD could be adapted to support people experiencing CPTSD.

Karatzias and Cloitre (2019) discussed the rationale, evidence and future directions for a modular approach to treating adults with CPTSD. Karatzias and colleagues (2019) also published a systematic review and meta-analysis examining psychological interventions for ICD-11 CPTSD symptoms.

A modular approach involves selecting and sequencing therapeutic interventions according to the person’s needs, rather than assuming that every person requires an identical programme in the same order.

For example, treatment planning may need to consider:

• PTSD symptoms, including intrusive memories, avoidance and a persistent sense of threat.
• Difficulties regulating emotions and managing distress.
• Negative beliefs about oneself, including shame or feelings of worthlessness.
• Relationship difficulties and the impact of trauma on trust and connection.
• Dissociation, safety concerns and other co-occurring difficulties.

These are not a checklist that every client must complete before treatment can begin. They are examples of areas that may be relevant to an individual assessment and treatment formulation.

The central principle is that treatment should be responsive to the person’s presentation, with interventions selected for a clear clinical purpose.

It is also important not to assume that everyone with CPTSD requires the same sequence of treatment, or that a modular approach automatically means delaying trauma-focused work. Decisions about timing and approach need to be informed by assessment, the evidence, clinical judgement and informed collaboration with the client.

What about people who experience both CPTSD and BPD?

This was one of the questions that particularly interested me during my dissertation research.

If someone meets criteria for both conditions, or experiences features associated with each, a treatment plan based on only one diagnosis may not fully address their needs.

My review discussed the possibility of integrating approaches, including DBT with trauma-focused interventions. It also identified emerging interest in combining EMDR with DBT for people experiencing PTSD alongside BPD. At the time of the literature I reviewed, this work was described as being underway; but that should not be mistaken for evidence of an established treatment outcome.

There is a difference between a promising research direction and a treatment whose effectiveness has been firmly demonstrated across different populations and settings.

The literature also suggested the need for further investigation into how approaches might be adapted for people with overlapping presentations. These questions cannot be answered simply by assuming that combining two therapies will automatically make treatment more effective.

The rationale, timing, suitability and outcomes of any combined approach need to be investigated carefully.

What does this mean for therapeutic practice?

For me, one of the most significant messages from this area of research is the importance of understanding the person behind the diagnosis.

A diagnosis can offer a useful framework, but it cannot tell us everything about a person’s experiences, coping strategies, relationships, strengths or therapeutic priorities.

A thoughtful assessment and formulation can help explore questions such as:

• What difficulties are causing the greatest distress at this point in the person’s life?
• Are trauma-related symptoms present, and how do they interact with other difficulties?
• What does the person want help with, and what are their priorities?
• What resources, relationships and coping strategies can support the therapeutic process?
• Which interventions have an appropriate evidence base for the difficulties identified?
• How will progress be reviewed, and how might the plan need to change over time?

This does not mean that treatment should be improvised or that evidence-based approaches are interchangeable. It means using evidence thoughtfully, while recognising that people do not always fit neatly into diagnostic categories or standard treatment pathways.

A trauma-informed approach also requires sensitivity to the possibility that discussing traumatic experiences may feel difficult or destabilising. Assessment and treatment need to be collaborative, appropriately paced and attentive to the person’s sense of safety and choice.

What were the limitations of the evidence I reviewed?

My dissertation was submitted in January 2022, and the evidence it considered reflected the literature available to me at that time. It should not be read as a statement of the current state of all treatment research.

Several limitations were important to keep in mind.

Different studies examined different outcomes. Improvement in PTSD symptoms, emotional regulation, self-harm, interpersonal functioning or quality of life does not necessarily mean improvement in every other area.

Some findings came from specific participant groups. Results from a pilot study or a study involving women with particular diagnoses may not transfer directly to all clients.

Co-occurring diagnoses complicate treatment research. People may experience overlapping symptoms and additional difficulties, making it challenging to determine which intervention contributed to which outcome.

The evidence base was developing. Some approaches were being adapted or combined, and further research was needed to establish their effectiveness, suitability and longer-term outcomes.

These limitations do not make the research unhelpful. They remind us to be precise about what the evidence supports, what remains uncertain and where further investigation is needed.

My reflections as a Traumatologist

Looking back at the literature I reviewed for my dissertation, I was struck by the importance of moving beyond a simple question of whether CPTSD and BPD are the same or different.

The distinction matters, but so does the question of how our understanding of these conditions influences the support people receive.

The treatment literature suggested that long established approaches for BPD, including DBT and MBT, have an important place in the field. Research into trauma-focused interventions and adapted or combined approaches also raised questions about how treatment might better address co-occurring PTSD, CPTSD and BPD-related difficulties.

However, I would not conclude that one therapy is universally best, or that a diagnosis alone determines the right treatment.

What stood out to me was the need for accurate assessment by an appropriate professional, a careful clinical formulation and an individualised plan informed by evidence and the person’s own priorities.

Research can guide us, challenge assumptions and help us develop better approaches. It cannot remove the need to listen carefully to the person sitting in front of us.

For me, this is where research and trauma-informed practice meet: in the ongoing effort to understand a person’s difficulties without reducing them to a label, and to offer support that is thoughtful, appropriate and responsive to their needs.

In the next article, I will explore what we still do not know about CPTSD and BPD, including the gaps in the research and the questions that remain important for clinicians and researchers.

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Further reading

• Harned MS (1), Gallop RJ, Valenstein-Mah HR. What changes when? The course of improvement during a stage-based treatment for suicidal and self-injuring women with borderline personality disorder and PTSD. Psychother Res. 2018;28(5):761–75. https://doi.org/10.1080/10503307.2016.1252865. 
• Harned MS (3), Korslund KE, Linehan MM. A pilot randomized controlled trial of dialectical behavior therapy with and without the dialectical behavior therapy prolonged exposure protocol for suicidal and self-injuring women with borderline personality disorder and PTSD. Behav Res Ther. 2014;55:7–17. https://doi.org/10.1016/j.brat.2014.01.008. 
• Harned MS (2), Wilks CR, Schmidt SC, Coyle TN. Improving functional outcomes in women with borderline personality disorder and PTSD by changing PTSD severity and post-traumatic cognitions. Behav Res Ther. 2018;103:53–61. https://doi.org/10.1016/j.brat.2018.02.002. 
• Harned, M.S., Rizvi, S.L., Linehan, M.M., 2010. Impact of co-occurring posttraumatic stress disorder on suicidal women with borderline personality disorder. Am. J. Psychiatry 167, 1210–1217. https://doi.org/10.1176/appi.ajp.2010.09081213.  
• Karatzias, T. and Cloitre, M. (2019). Treating adults with complex posttraumatic stress disorder using a modular approach to treatment: rationale, evidence, and directions for future research. Journal of Traumatic Stress, 32(6), 870–876. https://doi.org/10.1002/jts.22457
• Karatzias, T. et al. (2019). Psychological interventions for ICD-11 complex PTSD symptoms: systematic review and meta-analysis. Psychological Medicine, 49(11), 1761–1775. https://doi.org/10.1017/S0033291719000436
• Neacsiu AD, Lungu A, Harned MS, Rizvi SL, Linehan MM. Impact of dialectical behavior therapy versus community treatment by experts on emotional experience, expression, and acceptance in borderline personality disorder. Behav Res Ther. 2014;53:47–54. https://doi.org/10.1016/j.brat.2013.12.004. 
• Storebo OJ, Stoffers-Winterling JM, Vollm BA, Kongerslev MT, Mattivi JT, Jorgensen MS, et al. Psychological therapies for people with borderline personality disorder. Cochrane Database Syst Rev. 2020;5:CD012955. https://doi.org/10.1002/14651858.CD012955.pub2. 

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