How PTSD and CPTSD Became Distinct Diagnoses

Exploring the development of post-traumatic stress diagnoses, the recognition of complex trauma, and the research behind the distinction.

Understanding the history of PTSD

To understand why Complex Post-Traumatic Stress Disorder (CPTSD) is now recognised as distinct from Post-Traumatic Stress Disorder (PTSD), it helps to look at how our understanding of trauma-related difficulties has developed.

PTSD was formally introduced into the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) in 1980 (American Psychiatric Association, 1980). This was an important step in recognising the psychological impact of traumatic experiences within a formal diagnostic framework.

However, researchers and clinicians continued to observe that some people who experienced prolonged, repeated or particularly severe trauma presented with difficulties that appeared to extend beyond the symptoms traditionally associated with PTSD.

For some individuals, the effects of trauma seemed to reach into their sense of identity, their ability to regulate emotions and their capacity to feel safe in relationships. These observations contributed to growing discussion about whether the existing diagnostic categories adequately captured the range of responses to traumatic experiences.

From PTSD to the concept of complex trauma

During the 1990s, the concept of Disorders of Extreme Stress Not Otherwise Specified (DESNOS) was used in discussions about the broader and more pervasive difficulties that could follow severe or prolonged trauma.

This work contributed to an important question: could the effects of complex trauma be fully understood through the existing PTSD diagnosis, or was a more differentiated approach needed?

The distinction matters because trauma exposure does not produce one uniform response. A person may experience intrusive memories, avoidance and a heightened sense of threat, while also struggling with persistent shame, a damaged sense of self, difficulties managing emotions or problems feeling secure in relationships.

These difficulties may overlap, but they are not necessarily identical. Researchers began examining whether particular patterns of symptoms could be distinguished and whether those patterns could inform assessment and treatment.

This was not simply a debate about terminology. It concerned how psychological difficulties following trauma could be described accurately and understood in clinical practice.

Why was CPTSD not added to DSM-5?

The fifth edition of the DSM, published in 2013, revised the diagnostic criteria for PTSD. However, it did not establish CPTSD as a separate diagnosis. Instead, it included an expanded PTSD symptom framework (American Psychiatric Association, 2013).

This difference between diagnostic systems is important. The DSM and the International Classification of Diseases (ICD) are separate classification systems, and their approaches to trauma-related diagnoses have not been identical.

Jones and Cureton (2014) and Brewin and colleagues (2017) discussed concerns about whether the DSM-5 presentation of PTSD adequately represented the range of post-traumatic conditions described in the research.

The question was not whether PTSD was a valid or useful diagnosis. Rather, it was whether one diagnostic category could adequately capture the different ways in which people might be affected by traumatic experiences.

My dissertation explored this debate as part of the wider question of how CPTSD could be distinguished from PTSD and, subsequently, from Borderline Personality Disorder (BPD).

The introduction of CPTSD in ICD-11

A significant development came with the eleventh revision of the International Classification of Diseases (ICD-11), published by the World Health Organization.

ICD-11 recognises PTSD and CPTSD as distinct diagnoses (World Health Organization, 2018). This distinction reflects research suggesting that, although the conditions share important features, CPTSD involves additional difficulties beyond the core symptoms of PTSD.

Under the ICD-11 framework, PTSD centres on three broad areas:

• Re-experiencing the traumatic event in the present.
• Avoidance of reminders associated with the trauma.
• A persistent sense of current threat.

CPTSD includes the core features of PTSD alongside additional difficulties described as disturbances in self-organisation (DSO). These involve three further areas:

• Affect regulation: difficulties managing emotional responses.
• Negative self-concept: persistent beliefs about oneself as diminished, defeated or worthless, often accompanied by shame or guilt.
• Difficulties in relationships: problems sustaining relationships or feeling emotionally close to others.

In other words, a diagnosis of CPTSD includes the core PTSD features as well as clinically significant difficulties in these additional areas.

This framework offers a way of recognising that the effects of trauma may extend beyond fear-based responses and affect how a person experiences themselves, their emotions and their relationships.

It is important, however, not to assume that everyone who experiences prolonged trauma will develop CPTSD, or that these difficulties are exclusive to this diagnosis. Assessment requires consideration of the relevant diagnostic criteria and the person’s individual presentation.

What did the research contribute?

The distinction between PTSD and CPTSD did not emerge from a single study. It developed through a wider body of research examining symptom patterns and whether different profiles of post-traumatic difficulties could be identified.

Cloitre and colleagues (2013), Elklit and colleagues (2014), and Knefel and Lueger-Schuster (2013) reported findings that supported distinctions between PTSD and CPTSD in the populations they studied.

Across this research, two broad patterns were identified. One involved higher levels of core PTSD symptoms without the same level of additional difficulties in self-organisation. The other involved PTSD symptoms alongside greater difficulties with emotional regulation, self-concept and relationships.

These findings supported the argument that CPTSD could be meaningfully distinguished from PTSD, rather than being understood only as a more severe version of the same presentation.

However, research findings need to be interpreted carefully. Studies differ in their participants, assessment methods and analytical approaches. Evidence supporting a distinction between two diagnostic profiles does not mean that every individual will fit neatly into one category or that there is no overlap with other psychological difficulties.

The development of diagnostic categories is an ongoing process, informed by research, clinical observation and debate about how best to describe people’s experiences.

Why does this distinction matter in therapeutic practice?

For practitioners, the distinction between PTSD and CPTSD can offer a broader framework for understanding the impact of trauma.

Where PTSD criteria alone may not capture the full extent of a person’s difficulties, the CPTSD framework draws attention to emotional regulation, persistent negative beliefs about the self and problems with relationships, alongside the core symptoms of PTSD.

This can help inform assessment and clinical formulation. It may also support conversations about the different areas in which a person is experiencing difficulties, rather than focusing exclusively on traumatic memories or fear responses.

At the same time, diagnostic labels should not replace individual understanding. Two people with the same diagnosis may have very different histories, strengths, needs and ways of coping. A trauma-informed approach involves remaining curious about these differences and avoiding assumptions based solely on a diagnostic category.

It is also important to distinguish between identifying a diagnosis and deciding on appropriate treatment. The diagnostic framework can contribute to understanding a person’s presentation, but treatment decisions require a wider assessment of their circumstances, needs, preferences and clinical context.

Where does BPD fit into this discussion?

The recognition of CPTSD as distinct from PTSD also contributed to further questions about its relationship with BPD.

Some features associated with CPTSD and BPD overlap, including difficulties with emotional regulation, negative self-perception and relationships. This can make differential assessment complex, particularly when someone has experienced significant or prolonged trauma.

However, the distinction between PTSD and CPTSD is not the same as the distinction between CPTSD and BPD. Each question requires its own careful consideration of diagnostic criteria and research evidence.

This is the subject of a later article in this series, where I will explore the similarities and differences between CPTSD and BPD in more detail.

Continuing the research conversation

The development of CPTSD as a distinct diagnosis represents an important change in how trauma-related difficulties can be understood and classified.

My original dissertation examined this development as part of a wider review of the relationship between CPTSD and BPD. Revisiting the literature offers an opportunity to consider how diagnostic thinking has evolved, what the research supports, and where complexity remains.

This article reflects the literature reviewed for my dissertation, submitted in January 2022. It is not a comprehensive account of every subsequent development in diagnostic research; later evidence and changes will be identified separately where relevant.

In the next article, I will explore the similarities and differences between CPTSD and BPD, considering why these presentations can overlap and what the research suggests about distinguishing them.

Lisa Harris
Psychotherapist | Clinical Supervisor | Consultant | Qualified Traumatologist

lisaharris.uk

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References

American Psychiatric Association. (1980). Diagnostic and Statistical Manual of Mental Disorders (3rd ed.). American Psychiatric Association.

American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). American Psychiatric Association.

Brewin, C. R., Cloitre, M., Hyland, P., Shevlin, M., Maercker, A., Bryant, R. A., Humayun, A., Jones, L. M., Kagee, A., Rousseau, C., Somasundaram, D., Suzuki, Y., Wessely, S., van Ommeren, M. and Reed, G. M. (2017). A review of current evidence regarding the ICD-11 proposals for diagnosing PTSD and complex PTSD. Clinical Psychology Review, 58, 1–15. https://doi.org/10.1016/j.cpr.2017.09.001

Cloitre, M., Garvert, D. W., Brewin, C. R., Bryant, R. A. and Maercker, A. (2013). Evidence for proposed ICD-11 PTSD and complex PTSD: A latent profile analysis. European Journal of Psychotraumatology, 4, 20706. https://doi.org/10.3402/ejpt.v4i0.20706

Elklit, A., Hyland, P. and Shevlin, M. (2014). Evidence of symptom profiles consistent with posttraumatic stress disorder and complex posttraumatic stress disorder in different trauma samples. European Journal of Psychotraumatology, 5, 24221. https://doi.org/10.3402/ejpt.v5.24221

Jones, L. K. and Cureton, J. L. (2014). Trauma redefined in the DSM-5: Rationale and implications for counseling practice. The Professional Counselor, 4(3), 257–271. https://doi.org/10.15241/lkj.4.3.257

Knefel, M. and Lueger-Schuster, B. (2013). An evaluation of ICD-11 PTSD and complex PTSD criteria in a sample of adult survivors of childhood institutional abuse. European Journal of Psychotraumatology, 4, 22608. https://doi.org/10.3402/ejpt.v4i0.22608

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