Dissociative disorders — DID, OSDD and dissociative symptoms

What dissociation is

Everyone dissociates a little: you drive a stretch of road and cannot recall it, you disappear into a book. In a dissociative disorder it is not a moment but a structure. Awareness, memory, identity, the sense of one's body and the control of it — which normally hold together — have come apart, because at some point that was the only way to hold on.

It almost always follows feelings that could not be borne: usually repeated, serious harm early in life, with no one to turn to. The child could not get away, so it went away inside. That is a remarkable capacity. It becomes a problem when it keeps running long after the danger has passed.

We are licensed psychologists in Frederiksberg, central Copenhagen, and we offer the same treatment online, in English, anywhere in Denmark.

The diagnoses — ICD-10 F44 and ICD-11

In the Danish system the dissociative disorders are coded under F44 (DF44), "dissociative and conversion disorders", in ICD-10. We treat all of them:

• F44.0 Dissociative amnesia and F44.1 dissociative fugue.
• F44.2 Dissociative stupor, F44.3 trance and possession states.
• F44.4 Dissociative motor disorder — paralysis, weakness, tremor or gait disturbance with no neurological cause.
• F44.5 Dissociative convulsions — seizures that look like epilepsy but are not (PNES, functional seizures).
• F44.6 Dissociative anaesthesia and sensory loss — numbness, loss of vision, hearing or voice.
• F44.7 Mixed dissociative disorders.
• F44.8 Other dissociative disorders, including F44.81 dissociative identity disorder (DID) and what DSM-5 calls OSDD (ICD-11: 6B65, partial dissociative identity disorder).
• Depersonalisation–derealisation disorder (F48.1 in ICD-10, 6B66 in ICD-11).

F44.4–F44.7 are what ICD-11 calls dissociative neurological symptom disorder (6B60) and DSM-5 calls conversion disorder / functional neurological disorder (FND). They have their own page: functional neurological disorder — conversion, dissociative seizures and paralysis. It is the same mechanism as the other dissociative disorders, with the body as its site.

What we see most often

• Dissociative identity disorder (DID) — two or more distinct ways of being oneself, each with its own way of thinking, feeling and remembering, and gaps in memory between them. Many live with it for years without knowing what it is.
• OSDD (other specified dissociative disorder) — resembles DID, but without full amnesia, or without such sharply separated parts. It is the most common form, and the most often missed.
• Depersonalisation and derealisation — watching yourself from outside, feeling like a robot, or the world seeming behind glass, foggy, unreal. Often with a quiet terror of going mad. You are not.
• Dissociative amnesia — gaps in memory, explained away as "I'm just scatterbrained".
• Dissociative seizures, paralysis and sensory loss — see functional neurological disorder.
• Dissociation as part of complex PTSD — switching off in conversation, losing time, going blank.

Why it is so often missed

The average person with DID has been in the system for many years before anyone makes the right diagnosis. In the meantime it is called depression, anxiety, borderline, bipolar — and the treatment does not work, because it is aimed beside the target. Many have been told they are "treatment-resistant". They are not. They have not had the right treatment.

Part of the reason is that dissociation is built not to be seen. It hides from others and from the person. Switches between parts are often subtle, and the gaps in memory are explained away.

What could not be felt — the ISTDP understanding of dissociation

We work with Intensive Short-Term Dynamic Psychotherapy (ISTDP) as developed and researched by Allan Abbass, professor at Dalhousie University, Canada, with whom Simon Secher trained. ISTDP has a precise account of why dissociation arises — and, more importantly, of what makes it stop.

The core is simple. When a child is hurt by the people it depends on, feelings arise that have no room: rage at the person one loves; grief for what is lost; guilt about the rage. Those feelings cannot be felt without threatening the attachment, so they are repressed — and in place of the feeling comes anxiety. In Abbass's model that is not a metaphor. Unconscious anxiety takes particular pathways in the body, and dissociation is one of them:

• In some, anxiety goes to the striated muscles: tension, sighing, restless hands. Most can bear that.
• In others it goes to the smooth muscles: gut, airways, migraine, blood pressure.
• In some it goes to the cognitive–perceptual field: thinking stops, vision blurs, sound fades, you are "not there" — that is dissociation. Above a certain threshold the system simply disconnects, because the feeling on its way is too dangerous to feel.
• And it can go to motor control as conversion: a leg that will not carry, a hand that shakes, a seizure. See functional neurological disorder.

This means dissociation is not something to be talked out of or distracted from. It is a signal: right now we are approaching a feeling the system does not have the capacity for. Treatment is therefore to build that capacity — step by step, in the session, while it happens — so that feelings can gradually be felt without the body disconnecting. When they can, dissociation loses its function. It stops because it is no longer needed.

The effect of short-term dynamic therapy for conditions in which feelings become bodily symptoms is documented in several meta-analyses; see the references below.

How we work

Treatment of dissociative disorders is phased. That is the international standard, and there is a good reason for it: go straight to the trauma material before there is anything to stand on, and it gets worse, not better.

1. Stabilisation and safety. First everyday life: sleep, safety, being able to feel your body without disappearing, noticing the switches. We get to know your system. In ISTDP this is called building capacity: feeling a little more, a little longer, without disconnecting.
2. Cooperation inside. We do not work to make parts disappear. We work so that they stop being at war. Every part has had a job, and that job must be acknowledged before anything can change.
3. The feelings and the trauma. Only when there is capacity for it, and in doses that can be borne. We follow the anxiety closely — in the body, as we talk — and adjust before the system shuts down. Where it helps, we add EMDR.
4. Integration. For some that means parts merging. For others, living together with far less conflict and without memory loss. We do not decide the goal. You do — and your system does.

REAC neuromodulation as a supplement

As a supplement to psychotherapy we offer REAC neuromodulation — a gentle, non-invasive regulation of the nervous system, which we are the only clinic in Denmark to provide. A nervous system that has lived on alert for years disconnects more easily. REAC aims to lower that baseline, so there is more to work with in the sessions: more capacity, less switching off. Psychotherapy is the treatment; REAC supports it, and we do not offer it on its own.

What to expect

A longer course than for most other conditions. We say it plainly: it is not eight sessions. It is months, often longer. In return it is a course where we know what we are doing — we do not go too fast, and we do not go around.

And you set the pace. If a part of you is not ready for something, you are not ready for it. We respect that, not as a courtesy, but because that is how the treatment works.

Research

• Abbass A, Town J, Driessen E (2012). Intensive Short-Term Dynamic Psychotherapy: A Systematic Review and Meta-analysis of Outcome Research. Harvard Review of Psychiatry, 20(2), 97–108. doi.org/10.3109/10673229.2012.677347
• Abbass A, Kisely S, Kroenke K (2009). Short-term psychodynamic psychotherapy for somatic disorders: systematic review and meta-analysis of clinical trials. Psychotherapy and Psychosomatics, 78(5), 265–274. doi.org/10.1159/000228247
• Abbass A, Town J, Holmes H, Luyten P, Cooper A, Russell L, Lumley MA, et al. (2020). Short-Term Psychodynamic Psychotherapy for Functional Somatic Disorders: A Meta-Analysis of Randomized Controlled Trials. Psychotherapy and Psychosomatics, 89(6), 363–370. doi.org/10.1159/000507738
• Abbass A, Lumley MA, Town J, Holmes H, Luyten P, Cooper A, Russell L, et al. (2021). Short-term psychodynamic psychotherapy for functional somatic disorders: A systematic review and meta-analysis of within-treatment effects. Journal of Psychosomatic Research, 145, 110473. doi.org/10.1016/j.jpsychores.2021.110473
• Russell LA, Abbass AA, Allder SJ, Kisely S, Pohlmann-Eden B, Town JM (2016). A pilot study of reduction in healthcare costs following the application of intensive short-term dynamic psychotherapy for psychogenic nonepileptic seizures. Epilepsy & Behavior, 63, 17–19. doi.org/10.1016/j.yebeh.2016.07.017
• Malda-Castillo J, Howell B, Russell L, Town J, Abbass A, Perez-Algorta G, Valavanis S (2023). Intensive Short-Term Dynamic Psychotherapy (ISTDP) associated with healthcare reductions in patients with functional seizures. Epilepsy & Behavior, 141, 109147. doi.org/10.1016/j.yebeh.2023.109147
• Abbass A, Haghiri B (2025). Intensive Short-Term Dynamic Psychotherapy for Functional Somatic Disorders: A Scoping Review. Clinical Neuropsychiatry, 22(2), 111–120. doi.org/10.36131/cnfioritieditore20250201

Full reference list with DOIs: research and references (in Danish).