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How does DID/OSDD develop?


The theory of structural dissociation assumes that no one is born with an integrated personality. Instead, every person is born with different parts of themselves called ego states that are tied directly to needs. Over time, these ego states will naturally integrate into one seamless and coherent personality, generally by the age of about 7-9. 

However, childhood trauma will disrupt this process of integration. Ego states cannot merge and integrate due to conflicting needs, trauma responses, trauma memories, or learned actions due to trauma. A coherent sense of self cannot seamlessly form when the child is safe in one moment and in fight/flight/freeze/fawn the next, putting their body in survival mode. 

Depending on the degree to which the ego states cannot integrate, this can result in various disorders. For example, it can result in PTSD, c-PTSD, or BPD, or if it gets to the point where amnesiac barriers get built between the ego states to protect them from the knowledge of what’s happening to one another, it can result in DID.

Layman Terms Definition

Have you ever seen a little kid feel melancholy or bittersweet? Probably not! No, they’re usually happy, sad, hungry, tired, angry – the extremes. That’s because – according to the theory of structural dissociation – every one starts separate. Yeah, happy and sad can talk to each other, but they aren’t there at the same time. It’s one and then the other. 

Around 7-9 years old, those parts start naturally melding together.  The kid can feel complex emotions, so they aren’t so all-or-nothing anymore – it’s a natural part of development, right? Well, trauma kind of messes with that. 


Let’s say a child lives with her mom and her mom has a boyfriend who stays with them on the weekends. On the weekends, that boyfriend sexually abuses that child. And she knows her mom knows. This goes on for months, or even years, and she mentally can’t get through the week knowing what she will have to deal with on the weekend. She can’t talk to her mom and feels she can’t speak to anyone else – she’s a kid and doesn’t know what to do.

Her brain is still young, and her ego states (happy, sad, mad, scared) are still separate.  She develops structural amnesia so that she just forgets the weekend. And the part of her that experiences the weekend might just forget the week. They both live their own lives. Now one girl can get through the week and be a happy child without knowing about the trauma happening every weekend. Her brain has sectioned the weekend part away because that’s the abused and scared part. She doesn’t have communication with that part anymore. She has DID.  Now that she has developed that coping mechanism,  further trauma may cause her to split again.  She can produce more sectioned-off parts to deal with other traumatic things for the rest of her life because her brain learned that this works. That’s structural dissociation.

Core Theory

Core theory is the theory that there is one ‘original’ or ‘main’ personality. There are other alters who split off from that core. If there were to be a final fusion of a system – viewed through core theory – they would fuse back to be that core once more, just with more memories and understanding, and perhaps a few shifted traits from the alters who fused, but the core personality is generally seen as dominant in the sense that it will be withstanding throughout the system’s life. 

Core theory is less used nowadays, with structural dissociation being the leading theory in the field. That being said, with some systems identifying with a core, some people struggle with validating those alters if you still believe in the theory of structural dissociation. Firstly, identity should be respected and if that’s how their system identifies just respect them – it doesn’t matter your views outside. However, there’s also a reason some systems could identify more with a core while they still were formed through structural dissociation.

If a system went through their trauma after the majority of their ego states had already merged – they may have had what was an almost fully-formed identity with only one or two ego states left to merge when they ended up forming DID/OSDD. If that’s the case, they may have formed more of what might feel like a ‘core’ – rather than a system who had all their ego states separate still when they formed DID and therefore started out much more fractured. This is of course just a theory, but for systems out there who are struggling with feeling like they have a core but also believing in the theory of structural dissociation, this could potentially be an explanation. 

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