Co-occurrence of dissociation and anxiety and depressive disorders in adults: a scoping review.

Background: Dissociation, including depersonalization, derealization, dissociative identity disorder or dissociation in the context of functional neurological disorder, is classically associated with trauma-related disorders but is increasingly reported in anxiety and depressive disorders. Despite growing evidence linking dissociation to affective symptom severity, functional impairment, and treatment outcomes, its role in anxiety and depression remains insufficiently synthesized. Objective: This scoping review aimed to map the extent, nature, and characteristics of dissociation in adults with anxiety and depressive symptoms, with a focus on conceptualization, assessment methods, prevalence, and clinical correlates. Methods: Using Joanna Briggs Institute methodology and PRISMA-ScR guidelines, PubMed and Scopus were searched from inception to January 2025. Studies assessing dissociation in adults with anxiety and/or depressive symptoms using validated instruments or clinical interviews were included. Data were charted and synthesized thematically. Results: A total of 300 studies were included. Of these, 49 studies focused on depersonalization-derealization phenomena, 11 studies examined dissociative identity disorder or complex dissociative disorders, 139 studies investigated functional neurological disorders, and 101 studies addressed mixed or transdiagnostic dissociative phenomena. Across anxiety and depressive disorders, dissociative symptoms were common and dimensionally distributed across clinical samples, with severity varying by diagnosis, setting, and assessment method. In depersonalization-focused studies, approximately 41-43% of patients met criteria for at least one anxiety disorder, and comorbid depression was reported in 62% to 84.8% of clinical series. In functional neurological disorder populations, dissociative symptoms- most commonly assessed with the DES- were elevated in approximately 30-60% of patients and were strongly associated with comorbid anxiety and depression. In FND sample, anxiety and depressive symptoms were highly prevalent, affecting approximately one-third to two-thirds of patients. Across diagnostic categories, higher dissociation was consistently associated with greater symptom severity, increased functional impairment, higher rates of suicidality, and poorer treatment outcomes. Conclusions: This scoping review demonstrates that dissociation is a frequent and clinically relevant feature of anxiety and depressive disorders, extending beyond traditional dissociative diagnoses and intersecting with functional neurological symptoms. The findings support transdiagnostic and dimensional models of psychopathology, in which dissociation reflects stress-related disturbances in self-experience and emotional processing. Routine assessment of dissociative symptoms in anxiety and depression may enhance clinical characterization and inform more targeted interventions. Future research should prioritize longitudinal and mechanistic studies to clarify causal pathways and treatment implications. Systematic Review Registration: https://osf.io/hnjpb/, identifier hnjpb.