Neuroscience of dissociation reveals that dissociation isn’t something “going wrong” in the brain, it’s something trying to keep you safe. Dissociation and trauma are closely linked, especially when the mind has no other way to escape overwhelming fear or stress.
In extreme cases, this survival response can shape identity itself, as seen in dissociative identity disorder, reminding us that dissociation begins as protection, not pathology.
Dissociation is often referred to as a defense mechanism, but like the way our pulse is a function of our heart, dissociation is a normal function in our brain. Modern neuroscience has shed light on the biological processes behind dissociation, down from single neurotransmitters all the way to complex networks of brain regions communicating together.
Dissociation allows the mind to stay flexible and adaptive, navigating what to keep in awareness and what to set to the side for a more appropriate time. Dissociation also allows the brain to protect itself from overwhelming emotions and experiences by distancing them from consciousness.
Dissociation can become problematic when it the mind learns to rely on it too much, leaving individuals feeling disconnected from themselves, others and the world. For some people who have experienced trauma, dissociation becomes the preferred defense mechanism; in the face of overwhelming fear and double binds, dissociation became the escape when there was no escape.
Related: What Is Dissociation And How It Is Related To Trauma
Types of Dissociative Experiences
Dissociation is always the same in that something is being kept away from conscious awareness, but it can be experienced in many different ways. Classically symptomatic dissociation, sometimes called “Capital D Dissociation”, is more easily defined and readily noticeable to patients.
Relational dissociation or “lower case d dissociation” occurs in someone’s relationship to themselves or another person, and is much more subtle but just as impactful.
Symptomatic “Capital D” Dissociation
1. Derealization
An experience where the external world feels unreal, distant, or dream-like. People describe seeing things as flat, foggy, or artificial, as if perceived through glass. The environment is seen but not felt. This state is often triggered by acute stress or trauma, serving as a protective reduction of emotional intensity at the cost of vitality and connection.
2. Depersonalization
An experience of detachment from one’s own body, actions, or inner experience. People often look in a mirror and know they are seeing themselves but feel like they are looking at a stranger. Patients of mine report feeling like some sort of machine moving through the world autonomously.
3. Amnesia
Dissociative amnesia is the inability to recall personal information, usually loss of memory for a traumatic experience, that can’t be explained by ordinary forgetfulness. The failure might be in retrieval of stored memories due to dampened connectivity between certain brain regions.
In the case of trauma, the memory may never have forms in the first place. In moments of intense fear the surge of cortisol and adrenaline can overwhelm and shut down the brains memory centers.
4. Dissociative Fugue
A fugue state is characterized by sudden travel away from one’s usual surroundings and partial or complete loss of personal identity. During the episode, individuals may take on a new identity and later have no recollection of the experience. Fugue episodes often follow severe trauma or stress and resolve spontaneously.
5. Transient Global Amnesia
Sudden acute stress has been known, rarely, to cause a complete shut down of the memory function for up to and no more than 24 hours. People cannot remember the past or make any new memories for more than the last 30-60 seconds.
In the beginning the individual is actually quite distressed and frequently asking for orientation followed by a calmer period of complete amnesia. When the episode resolves memory function is fully restored.
6. Identity Fragmentation
This refers to a breakdown in the normally integrated sense of self, leading to the feeling of being a different person in different situations.
7. Dissociative Identity Disorder
At the extreme, distinct identities with their own memories and personality traits develop. Commonly called ‘alters’, each identity their own name and idiosyncrasies like different accents or handwriting. The original self does not have memory for alters, but in some cases the alters are aware of each other and may even find ways to communicate with each other.
DID most commonly develops in response to sexual abuse before age 7.
Relational “lower case d” Dissociation
Psychoanalyst Philip Bromberg deepened our understanding of dissociation by moving it out of symptomatic experiences and into the realm of identity. He elaborated that what we experience as ourself is not singular but composed of multiple self-states, each with its own organization of affect, memory, and perception.
Under ordinary conditions, these self-states flow into one another fluidly and one does not even notice the switching. Trauma can cause self states to become so incompatible with each other that communication between them can collapse and identify becomes fragmented.
Emotional responses can become inconsistent or vary widely based on context. It can also result in little ‘lacunae’ or islands of dissociation where a memory is forgotten in one context but remembered in another.
The Underlying Neuroscience of Dissociation
Although the brain is a single organ, it is composed of many highly specialized regions that are anatomically and physiologically different from each other. Each of these specialized brain regions work both in parallel and serial patterns to create the complexity needed to manage being human.
Dissociation is mediated by specific brain regions involved in emotional processing, cognition, memory storage and sensory experience.
Individual Brain Regions Involved in Dissociation
1. Prefrontal Cortex (PFC): Logic and Cognition
The prefrontal cortex, located right behind your forehead, helps you rationalize experiences and stay grounded in the present. During dissociation, the PFC’s activity decreases, making it harder to think clearly leading to confusion and disorientation. It becomes harder to make sense of your place in the world.
2. Amygdala: The Brain’s Fear Center
The amygdala, your brain’s system for marking intense emotions, reacts strongly to danger and labels what is dangerous to keep you on guard the next time you approach it. During dissociation, its activity can swing between extremes.
Reminders of traumatic experiences (triggers) can lead to hyper activation of the amygdala and potentially even flashbacks. In depersonalization or derealization, the amygdala is under active, dulling emotions and creating detachment. These shifts in amygdala activity highlight why dissociation can feel so different depending on the context.
Related: Structural Dissociation: How Complex Trauma Causes A Split In Our Being
3. Hippocampus: The Memory Hub
The hippocampus, essential for storing and recalling memories, malfunctions during dissociation. Cortisol and adrenaline can impair it’s normal functioning causing fragmented memories of traumatic events or potential amnesia.
4. Parietal Lobe: The Body in Space
The parietal lobe integrates sensory information, especially physical touch, to create a sense of your body in space. It helps you know where you end and the world begins. During dissociation, activity in the parietal lobe becomes disrupted blurring the boundary between self and environment, producing the eerie feelings of physical disconnection from the body or the world (or both).
5. Insula: Awareness of Bodily Sensations
The insula, buried deep within the folds of the cortex, links internal bodily sensations like heart beat and breathing into conscious awareness. In dissociation, the insula’s activity decreases, severing the ability to use your body to understand your emotional state. Individuals with borderline personality disorder are also likely to have poor interoceptive capacities.
Key Neurotransmitter Systems Regulating Dissociation
1. Glutamate and GABA: Systems in Balance
Glutamate excites brain cells but allowing an influx of positively charged Sodium ions into neurons; GABA calms down brain cells by stimulating the influx of negatively charged Chloride ions. Imbalances in glutamate and GABA signaling can lead to broader dysregulation in any brain region, with systems either over active or under active.
2. Cortisol and Adrenaline: Fight, Flight, Freeze and Fawn
Cortisol and adrenaline, hormone released by the adrenal glands, activates the body in the face of danger. It increases heart rate, blood pressure and a sense of alternates. Dissociation may cause the brain to either flood with cortisol or suppress it entirely, impairing your ability to process stress or trauma effectively.
Long term over-activation can cause a chronic state hyper-vigilance, anxiety and social behaviors like ‘fawning’ that are meant to preserve interpersonal safety.
3. The Opioid System: Natural Painkillers
The brain’s internal opioid system, which helps dull pain, can activate during dissociation. This helps explain the numbness and lack of physical or emotional sensation often reported by individuals experiencing dissociation.
Applying the Science to Specific Symptoms
The different types of dissociation have specific biological blueprints. Brain imaging studies reveal that the different symptoms are a manifestation of neural specific patterns and adaptations to trauma.
1. Derealization
Functional MRI studies show reduced activity in the amygdala and insula, alongside heightened activity in visual processing areas. Visual perception is heightened but emotional meaning is lost.
2. Depersonalization
Decreased communication between the prefrontal cortex and emotional processing centers cuts off awareness to feelings; increased activity in parietal lobe leads to hyper-awareness of the self. The decoupling leads to an eerie experience of self-consciousness without embodied emotional experience.
3. Amnesia
Under extreme stress, cortisol and adrenaline surges disrupt the hippocampus. The amygdala’s activity becomes disorganized and the emotional labeling of memories goes awry. The result is the conscious mind being unable to interact with or properly form memories.
4. Identity Fragmentation
Disruptions in communication between the prefrontal cortex and insula impair self awareness. Emotional expression, body language, and thinking patterns shift more easily between different context because the conscious mind can no longer regulate them.
Integrating Biology Into Treatment and Recovery
We can leverage biology into targeted and more highly effective treatments for trauma and dissociation. The goal is to normalize connections and communication across brain regions to restore a balanced way of adapting to the world.
Refined Psychotherapy
A trusting and safe relationship with a therapist teaches the body that social interactions don’t have to be fearful. The amygdala no longer needs to be in overdrive detecting threat, the hippocampus is no longer thrown off balance by stress hormones.
Techniques that emphasize grounding, body awareness, and relational repair directly strengthen these circuits. Trauma-focused approaches such as EMDR, AEDP, and insight oriented work work all help the hippocampus and amygdala lower the emotional intensity of traumatic memories, giving them less power.
Targeted Medications
Mood stabilizers like lamotrigine may reduce excessive glutamate activity, addressing the excitatory-inhibitory imbalance in the brain. SSRIs like Zoloft and Lexapro can normalize activity in the PFC and amygdala, helping regulate emotions.
Ketamine, which modulates glutamate at the NMDA receptor (which has to do with learning on an individual neuron level), has shown some promise in trauma work.
Related: What Is Dissociative Identity Disorder (DID): Symptoms and Treatment
Recovery from dissociation is a biological event, the brain re-learns safety and allows systems to fall back into balance. This doesn’t replace the human experience, it expands it. The work is done through experience and personal connection.
Written by Jason Shimiaie, M.D.
Originally Published on Substack
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