Studies have reported elevated rates of dissociative symptoms and comorbid dissociative disorders in functional neurological disorder (FND); however, a comprehensive review is lacking.

To systematically review the severity of dissociative symptoms and prevalence of comorbid dissociative disorders in FND and summarise their biological and clinical associations.

We searched Embase, PsycInfo and MEDLINE up to June 2021, combining terms for FND and dissociation. Studies were eligible if reporting dissociative symptom scores or rates of comorbid dissociative disorder in FND samples. Risk of bias was appraised using modified Newcastle–Ottawa criteria. The findings were synthesised qualitatively and dissociative symptom scores were included in a meta-analysis (PROSPERO CRD42020173263).

Seventy-five studies were eligible (FND n = 3940; control n = 3073), most commonly prospective case–control studies (k = 54). Dissociative disorders were frequently comorbid in FND. Psychoform dissociation was elevated in FND compared with healthy (g = 0.90, 95% CI 0.66–1.14, I2 = 70%) and neurological controls (g = 0.56, 95% CI 0.19–0.92, I2 = 67%). Greater psychoform dissociation was observed in FND samples with seizure symptoms versus healthy controls (g = 0.94, 95% CI 0.65–1.22, I2 = 42%) and FND samples with motor symptoms (g = 0.40, 95% CI −0.18 to 1.00, I2 = 54%). Somatoform dissociation was elevated in FND versus healthy controls (g = 1.80, 95% CI 1.25–2.34, I2 = 75%). Dissociation in FND was associated with more severe functional symptoms, worse quality of life and brain alterations.

Our findings highlight the potential clinical utility of assessing patients with FND for dissociative symptomatology. However, fewer studies investigated FND samples with motor symptoms and heterogeneity between studies and risk of bias were high. Rigorous investigation of the prevalence, features and mechanistic relevance of dissociation in FND is needed.

The dissociative disorders are characterized by a disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior.

We present the case of a 22-year-old patient, who has been following up for just over a year. The patient refers that two people inhabit her body, talk to each other, exchange opinions and both have control over the body, one giving the turn to the other depending on the circumstances. To this is added delusional symptoms of grandeur and sensorial-perceptual symptoms. In turn, depressive symptoms have appeared that have led the patient to have several suicide attempts throughout the follow-up time.

During this time, the patient has required hospital admission on two occasions due to the autolytic ideation. Treatment with neuroleptics and antidepressants has been established that have helped control delusions and thoughts of death, but not the dissociative clinic.

Dissociative Identity disorder 300.14 (F44.81)

The different symptoms presented by the patient, as well as the social and occupational deterioration that he presents, make this an extremely complicated case, both in diagnosis and in treatment. Dissociative identity disorder has been very controversial, changing its diagnostic criteria over time. More studies are needed and perhaps future research can give us more clues about this disorder.

No significant relationships.

Dissociative seizures (DS) are classified as dissociative convulsions within the group of dissociative disorders. Although they share many features with epileptic seizures (ES), they are not a consequence of abnormal brain discharges and may be related to psychogenic causes. DS represent a common diagnostic and are often confounded with ES.

The aim of this study is to review the current evidence about the differential diagnosis between DS and ES.

We conducted a non-sytematic review on the topic, using Pubmed/Medline database.

Studies emphasize a correct diagnosis before treatment of seizures. DS and ES respond differently to anticonvulsant medication and early or incorrect prescription of can even exacerbate DS. Clinical features and a neuropsychiatric history can also help. The presence of a dissociative “stigmata”, such as unexplained sensory loss, may support a non-epileptic diagnosis. EEG videorecording method is the gold standard diagnosis for DS, however often displays rhythmic movement artifacts that may resemble seizure activity and confound the interpretation. The absence of ictal EEG discharges characteristic of epilepsy is a sign of DS. However, this may not be true for some partial ES, particularly those from temporal lobes, whom also tend to report shorter duration of seizures, whereas patients with DPD often describe experiences lasting for hours or longer.

Distinguish DS from ES can be challenging. However, there are features that can help in the differential diagnosis. A correct diagnosis is essential for an adequate therapeutic approach, better prognosis, reduction of medical costs and also a referral to the right medical specialty.

No significant relationships.

Memory function is at the core of the psychopathology of dissociative identity disorder (DID), but little is known about its psychobiological correlates.

This study aims to investigate whether memory function in DID differs between dissociative identity states

Behavioural data and neural activation patterns were assessed in 92 sessions during an n-back working memory task. Participants were people with genuine diagnosed DID (n = 14), DID-simulating controls (n = 16) and a paired control group (post-traumatic stress disorder (n = 16), healthy controls (n = 16)). Both DID groups participated as authentic or simulated neutral and trauma-related identity states. Reaction times and errors of omission were analysed with repeated measures ANOVA. Working memory neural activation (main working memory and linear load) was investigated for effects of identity state, participant group and their interaction.

Identity state-dependent behavioural performance and neural activation was found. DID simulators made fewer errors of omission than those with genuine DID. Regarding the prefrontal parietal network, main working memory in the left frontal pole and ventrolateral prefrontal cortex (Brodmann area 44) was activated in all three simulated neutral states, and in trauma-related identity states of DID simulators, but not those with genuine DID or post-traumatic stress disorder; for linear load, trauma-related identity states of those with genuine DID did not engage the parietal regions.

Behavioural performance and neural activation patterns related to working memory in DID are dependent on the dissociative identities involved. The narrowed consciousness of trauma-related identity states, with a proneness to re-experiencing traumatising events, may relate to poorer working memory functioning.

It is unclear whether people with post-traumatic stress disorder (PTSD) and symptoms of complex PTSD due to childhood abuse need a treatment approach different from approaches in the PTSD treatment guidelines.

To determine whether a phase-based approach is more effective than an immediate trauma-focused approach in people with childhood-trauma related PTSD (Netherlands Trial Registry no.: NTR5991).

Adults with PTSD following childhood abuse were randomly assigned to either a phase-based treatment condition (8 sessions of Skills Training in Affect and Interpersonal Regulation (STAIR), followed by 16 sessions of eye-movement desensitisation and reprocessing (EMDR) therapy; n = 57) or an immediately trauma-focused treatment condition (16 sessions of EMDR therapy; n = 64). Participants were assessed for symptoms of PTSD and complex PTSD, and other forms of psychopathology before, during and after treatment and at 3- and 6-month follow-ups.

Data were analysed with linear mixed models. No significant differences between the two treatments on any variable at post-treatment or follow-up were found. Post-treatment, 68.8% no longer met PTSD diagnostic criteria. Self-reported PTSD symptoms significantly decreased for both STAIR–EMDR therapy (d = 0.93) and EMDR therapy (d = 1.54) from pre- to post-treatment assessment, without significant difference between the two conditions. No differences in drop-out rates between the conditions were found (STAIR–EMDR 22.8% v. EMDR 17.2%). No study-related adverse events occurred.

This study provides compelling support for the use of EMDR therapy alone for the treatment of PTSD due to childhood abuse as opposed to needing any preparatory intervention.

A large amount of literature surrounds the differences between dissociative neurological symptom disorder with non-epileptic seizures (DNSD-S) and epilepsy.

To explore the research gap on phenotypic differences between DNSD-S and other psychiatric disorders.

We conducted a case–control study of 1860 patients (620 patients with DNSD-S and 1240 controls with other psychiatric disorders) seen at the South London and Maudsley Hospital NHS Trust between 2007 and 2019.

Compared with the controls, the patients with DNSD-S were more likely to be female (76 v. 47%, P < 0.001), of White ethnicity (77 v. 60%, P < 0.001), married (34 v. 14%, P < 0.001) and living in areas of lower socioeconomic status (−3.79, 95% CI −2.62 to −4.96, P < 0.001). Two peaks for age at diagnosis were observed for DNSD-S: the early 20s and late 40s. After 31 years of age, men's chance of being diagnosed with DNSD-S increased from 19 to 28% (P = 0.009). People with DNSD-S presented more commonly with a history of a neurological episodic or paroxysmal disorder (OR = 12, 95% CI 7.82–20.26), another dissociative disorder (OR = 10, 95% CI 1.64– 65.95) or unclassified signs or symptoms (OR = 4, 95% CI 2.61–6.43). Neither anxiety, depression nor other somatoform disorders predicted subsequent diagnosis of DNSD-S, and controls had a larger proportion of preceding psychiatric diagnoses than patients with DNSD-S (65 v. 49%, P < 0.001).

This is the first study comparing demographic and phenotypic correlates of patients with DNSD-S against a large cohort of psychiatric patients. These data will inform development and drive service needs in psychiatry for people with DNSD-S.

It is clinically imperative to better understand the relationship between trauma, auditory hallucinations and dissociation. The personal narrative of trauma has enormous significance for each individual and is also important for the clinician, who must use this information to decide on a diagnosis and treatment approach.

To better understand whether dissociation contributes in a significant way to hallucinations in individuals with and without trauma histories.

Three groups of participants with auditory hallucinations were recruited, with diagnoses of: schizophrenia (without trauma) (n = 18), post-traumatic stress disorder (PTSD, n = 27) and comorbid schizophrenia and PTSD (SCZ+PTSD), n = 26). Clinician-administered measures included the PTSD Symptoms Scale Interview (PSSI-5), the Clinician-Administered Dissociative States Scale (CADSS) and the Psychotic Symptom Rating Scales (PSYRATS).

Dissociative symptoms were significantly higher in participants with trauma histories (PTSD and SCZ+PTSD groups) and significantly correlated with hallucinations in trauma-exposed participants, but not in participants with schizophrenia (without trauma history). Hallucination severity was correlated with the CADSS amnesia subscale score, but depersonalisation and derealisation were not.

Dissociation may be a mechanism in trauma-exposed individuals who hear voices, but it does not explain all hallucinatory experiences. The SCZ+PTSD group were in an intermediary position between schizophrenia and PTSD on dissociative and hallucination measures. The PTSD and SCZ+PTSD groups experienced dissociative phenomena much more frequently than the schizophrenia group, with a significant trend towards the amnesia subtype of dissociation.

Many patients with post-traumatic stress disorder (PTSD) experience dissociative symptoms. The question of whether these dissociative symptoms negatively influence the effectiveness of psychotherapy for PTSD is unresolved.

To determine the influence of dissociative symptoms on psychotherapy outcome in PTSD.

We conducted a systematic search in Cochrane, Embase, PILOTS, PsycINFO, PubMed and Web of Science for relevant clinical trials. A random-effects meta-analysis examined the impact of dissociation on psychotherapy outcome in PTSD (pre-registered at Prospero CRD42018086575).

Twenty-one trials (of which nine were randomised controlled trials) with 1714 patients were included. Pre-treatment dissociation was not related to treatment effectiveness in patients with PTSD (Pearson's correlation coefficient 0.04, 95% CI −0.04 to 0.13). Between-study heterogeneity was high but was not explained by moderators such as trauma focus of the psychotherapy or risk of bias score. There was no indication for publication bias.

We found no evidence that dissociation moderates the effectiveness of psychotherapy for PTSD. The quality of some of the included studies was relatively low, emphasising the need for high-quality clinical trials in patients with PTSD. The results suggest that pre-treatment dissociation does not determine psychotherapy outcome in PTSD.

None.