Questioning the structural validity of trauma-related dissociative disorders: The latent structure of pathological dissociation across diagnostic groups.

Background: Models of trauma-related dissociation rely on two conflicting assumptions: dissociation as a single transdiagnostic severity continuum versus dissociative disorders as categorically distinct from PTSD. Neither has been tested at the level of symptom organization across diagnostic contexts. We investigated whether pathological dissociation retains its internal structure across psychiatric populations or reorganizes specifically in trauma-related conditions. Methods: We analyzed cross-sectional data from 1,475 psychiatric inpatients: dissociative disorders (n=388); PTSD without dissociative disorders (n=861); and other diagnoses, predominantly depressive disorders (n=226). Measurement invariance (MI) testing and multi-group exploratory factor analysis were applied to the Dissociative Experiences Scale-Taxon (DES-T). Results: MI was rejected (scaled Δχ²(14) = 33.96, p = .002). In general psychiatric patients, dissociation formed a single dimension. In trauma-related conditions, it separated into three partially independent components: depersonalisation/derealisation, amnesia, and identity dissociation. This organization was nearly identical across PTSD and dissociative disorder groups. These groups differed primarily in childhood trauma severity and dissociative symptoms, while maintaining comparable PTSD symptom burden. Conclusions: Dissociation is not a universal severity continuum. Instead, trauma exposure is associated with a qualitative reorganisation into separable clinical domains shared by PTSD and dissociative disorders. Diagnostic boundaries between these conditions may reflect different severity levels of shared trauma-related processes rather than distinct pathologies. Current treatment pathways excluding highly dissociative patients from trauma-focused therapy lack empirical justification and require reconsideration.