How our understanding of trauma and dissociation changed

The explanation kept changing

Dissociation has been around for a long time before psychiatry finally gave it a name. Old accounts describe people who lost time, acted without meaning to, or suddenly appeared unlike themselves. Some had pain or paralysis with no obvious injury.¹

Doctors repeatedly connected overwhelming experiences with psychological symptoms. Then later generations forgot, rejected, or reinterpreted their work, and the same ground had to be covered again. The history is full of rediscoveries!¹²

At different points, those experiences were blamed on the body, spirits, fragile nerves, heredity, weak character, fantasy, or overwhelming events. Ideas about women, children, and personal responsibility shaped who was believed and who was blamed for their own suffering.¹

Ancient and medieval accounts describe people losing speech, becoming paralysed, convulsing, forgetting what happened, or behaving in ways that seemed unlike them. Some returned to ordinary life between these episodes.¹ A modern clinician might split those accounts across dissociative, neurological, trauma-related, sleep, and other conditions.

Nijenhuis keeps coming back to the same dispute: was the person reacting to an injurious world, or did the symptoms expose something supposedly wrong with their body, character, or imagination?¹

Hysteria wasn't one illness

Historian Helen King went back to the texts behind the familiar story of hysteria. Hippocratic writers discussed illnesses associated with the womb, but later writers took a much broader diagnosis and projected it backward onto those ancient accounts.³

By the nineteenth century, hysteria covered symptoms that would now be spread across dissociative disorders, functional neurological disorder, epilepsy, trauma-related conditions, and more. Men received the diagnosis too, but the category remained heavily gendered. A woman's pain, paralysis, fear, anger, sexuality, or resistance could all be interpreted through assumptions about sensitivity, reproduction, and dependence.³

When possession explained a change in self

Some accounts of possession include changes in voice or behaviour, gaps in awareness, inner conflict, and the feeling that another force has taken control. Modern readers may recognise parts of those descriptions.¹

This doesn't necessarily mean those experiences lined up perfectly with what we know now as DID. Possession can be part of accepted religious practice, a way of expressing distress, a neurological or psychiatric condition, deliberate performance, or several of those things at once.¹

Janet asked a different question

Pierre Janet worked with patients who could lose access to a memory while its emotion or bodily response continued. He asked how an overwhelming experience could remain active without becoming part of ordinary consciousness and autobiographical memory.⁴

In Janet's account, an overwhelming experience could continue outside ordinary awareness. Sensations, actions, emotions, and memories might return through intrusions, bodily symptoms, re-enactments, or altered states.⁴

A railway accident and an argument

After railway accidents, some survivors were left with pain, fear, memory problems, paralysis, or disturbed sleep even when doctors could find no obvious physical injury. Their cases pushed one question into public view: could fright itself injure a person?¹

The answer affected who paid. If psychological injury counted as a real injury, railway companies could be held responsible. If the symptoms were dismissed as weakness or fraud, that responsibility mostly disappeared.¹

The same gap appeared in accounts of child abuse. In nineteenth-century France, forensic physician Auguste Ambroise Tardieu painstakingly documented abuse of children. The evidence existed. What often failed was connecting those experiences to later psychological suffering.¹ Knowing that harm happened and recognising what it did to a person have not always arrived together.

War changed the argument

During the First World War, soldiers developed tremors, paralysis, mutism, nightmares, memory loss, altered states, and emotional collapse. There were too many cases to dismiss as an odd weakness in one man. Military doctors still disagreed over what had been injured: the brain, the nerves, the mind, or the man's character.⁵

Ask someone to picture shell shock and they will probably picture a man returning from the trenches. Women were there too, including nurses, but they are easy to lose from that familiar image.⁵ Even among soldiers, the response depended on class, rank, and whether the military still considered a man useful. One man might be treated as injured. Another could be called a coward or accused of faking.

A century later, men are still expected to absorb danger, stay useful, and keep quiet about what it costs them. “Male disposability” is one political name for that bargain. In 2021, the global male suicide rate was more than twice the female rate.⁶ A 2025 meta-analysis linked traditional masculine norms with more self-stigma and more negative attitudes toward psychological help.⁷ Other meta-analyses have found associations between suicidal behaviour and both PTSD and dissociation.⁸⁹

PTSD entered the DSM

Post-traumatic stress disorder entered DSM-III in 1980 after years of research and advocacy involving Vietnam veterans, Holocaust survivors, survivors of sexual trauma, and others.¹⁰

PTSD made the event itself part of the diagnosis. In other words, psychiatry now had a way to describe an otherwise ordinary person as injured by what happened to them.¹⁰ Railway accidents and shell shock had raised that question long before the name PTSD existed.¹

When “multiple personality” became DID

Ideas about divided consciousness, amnesia, automatisms, hypnosis, and alternating states had circulated for decades before a modern diagnostic category was created.⁴ Multiple personality disorder entered DSM-III in 1980. It was renamed dissociative identity disorder in DSM-IV in 1994.¹¹

"Multiple Personality" suggests that several people or personalities inhabit the same body. “Dissociative identity” instead points to discontinuity within one person's identity, memory, agency, and consciousness.¹¹

The next revision kept moving in that direction. The DSM-5 work group wanted the criteria to say more clearly that amnesia can involve ordinary daily events, and that identity disruption can appear in possession form.¹²

By 2014, Dorahy and colleagues could review DID research on diagnosis, lived symptoms, prevalence, trauma, memory, neurobiology, and treatment. Many of the studies were small, and diagnostic disagreement remained. Isolated case histories were no longer carrying the whole discussion; researchers were comparing groups, testing memory, estimating prevalence, and following treatment.¹³

Footnotes13

Nijenhuis, E. R. S. (2015). The trinity of trauma: Ignorance, fragility, and control, Volumes I and II. Vandenhoeck & Ruprecht. Volume I, historical accounts of trauma, hysteria, war neurosis, and dissociation. Historical and theoretical account. The author advances a particular trauma and structural-dissociation framework, so interpretive claims are identified as his perspective. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹
Herman, J. L. (1992). Trauma and recovery: The aftermath of violence, from domestic abuse to political terror. Basic Books. Historical account of trauma recognition and its social context. Influential historical and clinical synthesis of trauma, including the recurring recognition and neglect of trauma-related suffering. ↩
King, H. (1993). Once upon a text: Hysteria from Hippocrates. In Hysteria beyond Freud (pp. 3-90). University of California Press. Historical interpretation of Hippocratic texts and later constructions of hysteria. Historical scholarship cautioning against treating ancient writings as a single continuous psychiatric diagnosis. ↩ ↩²
van der Hart, O., & Horst, R. (1989). The dissociation theory of Pierre Janet. Journal of Traumatic Stress, 2(4), 397-412. Abstract. Historical account of Janet's theory of dissociation as a response to overwhelming experience and of his concepts of memory, emotion, and psychological integration. ↩ ↩² ↩³
Loughran, T. (2013). A crisis of masculinity? Re-writing the history of shell-shock and gender in First World War Britain. History Compass, 11(9), 727-738. Abstract. Historical review of how war trauma was interpreted through gender and social context, cautioning against a single account of shell shock. ↩ ↩²
World Health Organization. (2025). Suicide worldwide in 2021: Global health estimates. p. 4, Global epidemiology of suicide. WHO estimates showing a global age-standardized suicide rate of 12.3 per 100,000 for males and 5.6 for females in 2021. ↩
Üzümçeker, E. (2025). Traditional masculinity and men's psychological help-seeking: A meta-analysis. International Journal of Psychology, 60(2), e70031. Abstract; meta-analysis of 35 samples. Meta-analysis associating stronger endorsement of traditional masculinity with more negative help-seeking attitudes and greater self-stigma. ↩
Akbar, R., Arya, V., Conroy, E., Wilcox, H. C., & Page, A. (2023). Posttraumatic stress disorder and risk of suicidal behavior: A systematic review and meta-analysis. Suicide and Life-Threatening Behavior, 53(1), 163-184. Abstract; systematic review and meta-analysis. Meta-analysis finding associations between PTSD and death by suicide, attempted suicide, and suicidal ideation. ↩
Calati, R., Bensassi, I., & Courtet, P. (2017). The link between dissociation and both suicide attempts and non-suicidal self-injury: Meta-analyses. Psychiatry Research, 251, 103-114. Abstract. Meta-analysis of 19 studies comparing suicide attempts and non-suicidal self-injury in psychiatric patients with and without dissociative disorders. ↩
National Center for PTSD. (n.d.). History of PTSD in veterans: Civil War to DSM-5. PTSD added to DSM-III in 1980; veteran, feminist, and Holocaust-survivor advocacy. VA overview of the historical development of PTSD and the research and advocacy contributing to its inclusion in DSM-III. ↩ ↩²
Young, M., Almaskati, M., Vrabtchev, S., & Kuruvilla, T. (2024). Dissociative identity disorder: A review of the diagnosis that divides. Progress in Neurology and Psychiatry, 28(2), 23-27. Diagnostic history and current DSM/ICD descriptions. Clinical review of DID's diagnostic history, classifications, controversies, and current clinical implications. ↩ ↩²
Spiegel, D., Loewenstein, R. J., Lewis-Fernandez, R., Sar, V., Simeon, D., Vermetten, E., Cardena, E., & Dell, P. F. (2011). Dissociative disorders in DSM-5. Depression and Anxiety, 28(9), 824-852. Abstract and recommendations. The DSM-5 work group's review and its recommendations to emphasize disruptive dissociation, everyday amnesia, and possession-form presentations. ↩
Dorahy, M. J., Brand, B. L., Sar, V., Kruger, C., Stavropoulos, P., Martinez-Taboas, A., Lewis-Fernandez, R., & Middleton, W. (2014). Dissociative identity disorder: An empirical overview. Australian and New Zealand Journal of Psychiatry, 48(5), 402-417. Abstract and review scope. DID-specific empirical overview that discusses accumulating evidence, ongoing controversy, and research limitations. ↩