With our understanding of DID and complex dissociative disorders (CDDs) growing more over the last few decades, we feel it is imperative to discuss why the Structural Dissociation Model (SDM, a specific form of the formerly commonplace trauma model used to understand and explain how an individual could develop DID) fell out of favour. Such a decision was made due to observations of the SDM still being used to explain the formation of DID and other dissociative disorders — the phenomenon bearing resemblance to people from prior generations previously referring to DID as MPD even decades after the disorder’s change in name and understanding in the DSM-IV.
The trauma model assumes early childhood severe trauma and the development of dissociative symptoms are directly related, particularly in individuals with a hereditary predisposition to dissociation. Dissociative reactions are seen as a learned coping mechanism for surviving long-term childhood traumatisation in the model. It is believed such a coping mechanism allows a person to cope with the fear, pain, and cognitive dissonance which arose from the traumatic experiences, often caused by someone the person was dependent on (e.g. a parent or caretaker, a relative, an authority figure) as a child. The SDM, grounded in this trauma framework, posits that developmental trauma disrupts the child’s capacity to integrate emotional, cognitive, and somatosensory experiences, resulting in a fragmented sense of self — i.e. a “structural” division of the personality into multiple compartmentalised (split up) parts, of which there is inter-identity dissociative amnesia: Memory gaps from when another identity assumed control of behaviour. In this model, emotionally vulnerable parts who retain the memories of traumatic experiences and remain fixated on the past are called “emotional personalities (EPs)”. EPs retain the affective states and survival mechanisms linked to the traumatic experiences. Conversely, parts that remain unaware (amnesic) of the traumatic events due to psychological compartmentalisation are called “apparently normal personalities”. These parts tend to take care of most obligations and duties in daily life.
However, neurobiological research presented to claim identification of a biomarker for dissociative amnesia has been criticised for several reasons. For instance, a common criticism towards this research is its index for dissociative amnesia is based solely on subjective self-report measures instead of cognitive memory tasks, and it was unclear whether the results were specific to DID or also evident for other comorbid disorders. Not to mention the unreliable identification of biomarkers for dissociative symptoms, and considerable variation of implicated brain regions across studies. Lastly, the reversible nature of dissociative amnesia seems incongruent with structural brain abnormalities.
Additionally, findings from fundamental empirical research on inter-identity amnesia and further cognitive identity functioning have established insights important to the conceptualisation and treatment of DID. Instead of assuming the presence of a structural “division of the personality”, research from the 2000s and onwards where objective tasks were used to measure inter-identity amnesia has repeatedly shown this assumption is incorrect. Transfer of knowledge between identities was found in episodic (short-term), semantic (long-term), autobiographical, and procedural (unconscious long-term) memory, as well as neutral, self-relevant, and trauma-related information. Not to mention, DID has been shown to be related to impairments in subjective self-clarity, but not differences in the self-concept structure when more objective cognitive tasks are used.
These reasons, alongside certain other alternative explanations constructed to justify the empirical findings that support this model, make the trauma and SDM model less apt and accurate at explaining the formation of DID in individuals compared to other posited, more recent models such as the schema mode model developed by Young et al.
Really goes to show public education on DID among laypersons lags behind that of research to a somewhat worrying degree. DID education and further research surely has a very long way to go. - 🧠
