30 Dissociation and its biological and clinical correlates in functional neurological disorder: a systematic review and meta-analysis
Bibliographic record
Abstract
Objectives/Aims Dissociation is a potential mechanism in FND. Although scientific studies report elevated rates of dissociative symptoms in FND, a systematic assessment of the biological and clinical correlates of dissociation in FND is lacking. We aimed to systematically review the current evidence describing dissociative symptoms and disorders in functional neurological disorder (FND), and additionally conduct a meta-analysis of dissociative symptom severity in FND. We also aimed to synthesise the existing data on biological and clinical correlates of dissociation in FND. Methods We systematically searched Embase, PsycINFO, and Medline, combining terms for FND and dissociation. Studies were eligible for inclusion if reporting on dissociative symptom scale scores or rates of dissociative disorder in FND samples. Studies were appraised for methodological quality using modified Newcastle-Ottawa criteria. Findings pertaining to dissociative symptoms or disorders, as well as biological and clinical correlates of dissociation in FND samples, were synthesised qualitatively. Dissociative symptom scores were included in a meta-analysis using random and mixed effects models. Results Two-thousand and eighty-eight records were screened and seventy-nine studies were included in the final review. Dissociative symptoms were elevated in FND. The meta-analysis demonstrated a significant elevation in dissociation in FND samples relative to neurological and healthy controls, but not psychiatric controls. Dissociative disorders were frequently co-morbid in FND samples. Psychoform (cognitive) dissociation was more prominent in FND-seizures, whereas somatoform (physical) dissociation tended to be more prominent in FND-motor symptom samples. Dissociation was associated with FND symptom severity or frequency, general psychopathology, and reduced quality of life. Biological correlates of elevated dissociation included structural and functional brain alterations in regions that have previously been implicated in FND, such as the anterior cingulate cortex. Conclusions Dissociative symptoms and disorders are common in FND, and different FND subgroups appear to endorse varying degrees of psychoform or somatoform dissociation. Presence of dissociative symptoms in FND is associated with adverse clinical features; there is therefore a clinical need to assess patients with FND for dissociative symptomatology and to address these symptoms during treatment. Future research should examine dissociation further in different FND subgroups, using measures that distinguish between different types of dissociation, alongside measures of underlying pathophysiology.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.016 | 0.036 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.017 | 0.036 |
| Bibliometrics | 0.009 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".