Post-traumatic stress disorder (PTSD), complex PTSD (CPTSD), and borderline personality disorder (BPD) exhibit significant symptom overlap . Evaluating underlying psychological processes (i.e.motion regulation [ER] dissociative experiences, and traumatic experiences (TEs) may offer clearer diagnostic differentiation.

We adopted a mechanism-oriented approach to identify configurations of ER strategies, dissociative experiences, and lifespan TEs. Multivariate comparisons were conducted in a convenience community sample ( N  = 347) screened for PTSD, CPTSD, and BPD, controlling for BPD criteria counts due to high comorbidity.

The sample comprised probable CPTSD with ( N  = 20) and without BPD ( N  = 8), PTSD + BPD ( N  = 37), PTSD ( N  = 18), BPD ( N  = 83), and controls with no self-report diagnoses ( N  = 181). CPTSD (with and without BPD) was distinctly differentiated by more severe childhood TEs, particularly physical abuse, neglect, and sexual abuse. ER strategies and dissociation experiences represented dimensions transversal across groups in terms of severity. Accounting for the effects of BPD psychopathology, significant differences were detected between the CPTSD + BPD and BPD groups. "

The findings suggest shared difficulties and selective differences in developmental trauma, ER, and dissociative experiences across probable diagnostic profiles. Intriguingly, CPTSD could be distinguished from PTSD and BPD by the severity of specific developmental TEs, experiential avoidance, dissociation, and a lower capacity for cognitive reappraisal. However, the results for CPTSD without BPD require replication in larger samples. Our findings may enhance clinical formulation and support more targeted, process-focused interventions