Susannah Pick

Background: Affective hyperarousal and dissociation are possible mechanisms underlying symptom occurrence in functional neurological disorder (FND), although evidence is limited by retrospective and cross-sectional measurement. We aimed to examine these mechanisms in everyday life with digital remote monitoring technologies in functional seizures (FS) and functional motor symptoms (FMS).Methods: Smartphone-based ecological momentary assessment (EMA) tracked subjective functional neurological symptoms (FNS), subjectively significant daily events, affect, dissociation, and subjective arousal six times daily over 14 days, alongside wearable heartrate monitoring (Fitbit Charge 5). Participants were aged 18-65 years with FS (n=45) or FMS (n=48). Healthy (HC, n=45) and clinical controls with anxiety/depressive disorders (CC=47) were included for comparison. We used linear mixed-effects models to compare groups and to interrogate concurrent and time-lagged temporal relationships between variables. Results: FS and FMS groups reported elevated dissociation across the 14 days compared to CC/HC (p≤0.01), including depersonalisation, derealisation, and amnesia (p<0.05). Reduced event-related pleasantness was also reported by FS/FMS/CC groups compared to HC (p<0.05). At the day- and momentary-levels, dissociation was the most robust correlate and/or temporal predictor of FNS severity in the FS/FMS groups (p=0.02-<0.001), withstanding correction for confounds. Event-related stress/pleasantness ratings, negative affect, and subjective arousal significantly predicted FNS severity in some models.Conclusions: Dissociation is a distinguishing feature in FS/FMS and a prominent correlate and momentary temporal predictor of FNS severity in both groups, indicating a possible shared mechanism. Future studies should examine the neurobiological basis of dissociation-FNS interactions and explore interventions that enhance management of dissociative states in this population.

Background: Dissociative identity disorder (DID) is associated with frequent psychiatric comorbidity. Its complex and overlapping symptom profile can complicate recognition of both DID and co-occurring psychiatric conditions, contributing to diagnostic uncertainty. Evidence regarding psychiatric comorbidity is limited and prevalence estimates vary across studies. Aims: This meta-analysis aimed to examine the prevalence of psychiatric comorbidities in DID and factors associated with variation in prevalence estimates. Methods: Eligible studies were identified through PubMed, Scopus, Embase, PsycINFO, and MEDLINE from 1980 to 25 April 2026 (PROSPERO, no. CRD420261335819). Studies reporting psychiatric comorbidity in adults with DID were independently screened by two reviewers. Risk of bias was assessed. Random-effects meta-analyses using logit-transformed prevalence estimates were conducted. Meta-regressions examined moderators, whilst influence and sensitivity analyses assessed robustness. Certainty was evaluated using the GRADE approach. Results: Twenty-four studies ( N = 858) contributed to the meta-analysis across 23 psychiatric comorbidities. Among individuals with DID, posttraumatic stress disorder had the highest pooled prevalence (87.44%, 95% CI 71.79–94.96), followed by major depressive disorder (62.64%, 95% CI 33.45–84.84), and borderline personality disorder (47.05%, 95% CI 34.21–60.32). Substantial heterogeneity was noted across most estimates. Meta-regressions identified significant associations with participant characteristics, recruitment, study quality, and diagnostic method. Risk of bias and certainty of evidence were heterogenous. Conclusions: Psychiatric comorbidity in DID is substantial and spans multiple diagnostic categories, although considerable heterogeneity and methodological variation limit confidence in prevalence estimates. Standardised diagnostic assessment, more representative sampling, and longitudinal research are needed to clarify the extent and clinical significance of comorbidity in DID.

Functional neurological disorder (FND) is characterized by involuntary, distressing neurological symptoms that are distinguishable from other neurological diagnoses in presentation, aetiology and mechanisms. Significant disability, impaired quality-of-life and substantial healthcare resource utilization often result from the disorder, yet its underlying mechanisms have not been proven empirically. Importantly, long-term clinical trajectories and predictive markers have been understudied in FND cohorts. Inadequate funding of large-scale mechanistic and longitudinal research, methodological limitations and the absence of standardized outcome measures necessitate development of innovative solutions. Digital remote monitoring technologies (dRMTs), which have been shown to be valuable across a range of other neurological and psychiatric disorders, may have substantial potential to address these research challenges in FND, yet this potential is currently unrealized. We propose that dRMTs could be harnessed to monitor subjective and/or objective functional neurological and associated symptoms, mechanistic variables and important outcome domains, with excellent temporal precision, flexibility and external validity. These methods could allow precise characterization of both short- and long-term fluctuations in FND symptoms, the influences on them and their impact on patients. Such data would strengthen mechanistic models, improve outcome prediction and facilitate personalized FND clinical management in this underserved population. This article is part of the discussion meeting issue ‘Digital healthcare for the management of functional neurological disorders’.

Accumulating evidence suggests alterations in neurocognitive, affective, interoceptive and autonomic processing in functional neurological disorder (FND), yet interventions targeting these processes remain underexplored. This study investigated the possible immediate and longer-term effects of a somatic yoga intervention on cognitive control, emotion regulation, state dissociation and affect, autonomic arousal, and interoceptive processing in FND. Twenty-three adults with FND completed six weeks of somatic yoga (N=12) or six weeks of a music-based relaxation control (N=11). At baseline, post-single session, and post-six weeks, participants completed laboratory measures of sustained attention, response inhibition, interoception, emotion regulation, and state dissociation and affect. Electrocardiography and galvanic skin conductance were recorded throughout. Linear mixed effects models assessed potential change on day one, immediately pre/post a single session, and from day 1 to the end of the six-week programme. After one session, stop signal reaction time, negative affect, and heartrate decreased in both groups (Δ=.69-.75). After one session and at six weeks, improved sustained attention, elevated positive affect, and reduced dissociation were seen in both groups, with a larger magnitude of change in yoga (Δ=.50-1.10). The yoga group exhibited fewer direction errors on the response inhibition task and shorter response times on the sustained attention task, with the opposite seen in the music group (Δ=.50-1.17). Both in the short- and longer-term, somatic yoga might lead to adaptive changes in attention and executive functioning, arousal, state affect and dissociation.

Background: Functional neurological disorder (FND) is characterised by disabling motor, sensory and/or seizure symptoms. Contemporary models highlight the possible involvement of altered affective and autonomic regulation and interoceptive processing in FND. However, accessible, mechanism-informed interventions remain limited. Aims: This study sought to examine the feasibility, acceptability and possible benefits of tailored somatic yoga for people with FND, aiming to directly target altered emotional and bodily regulation in this group. Method: This single-site, two-arm randomised feasibility trial allocated adults with FND to 6 weeks of either somatic yoga (weekly remote sessions plus home practice manual) or a music-based relaxation control. Feasibility outcomes included recruitment, retention, adherence and acceptability. Secondary outcomes, assessed at baseline, week 3, week 6 and 3-month follow-up, included FND symptom burden, psychological symptoms (anxiety, depression, dissociation), general functioning, health-related quality-of-life, interoceptive awareness and autonomic symptoms. Results: Seventy-six enquiries were received. Thirty participants consented (100%), 27 were randomised (90%), 23 commenced the trial (77%) and 21 completed it (70%). Recruitment and retention targets were met, with 100% retention in the yoga arm. Adherence was high across both groups, although digital logging of home practice posed usability challenges. Exploratory analyses indicated large effect sizes for self-reported FND symptom improvement and interoceptive awareness in the yoga group, with effects sustained at follow-up. Conclusions: Individually delivered somatic yoga was found to be feasible, acceptable and safe for people with FND. Our results also suggest potential benefits of somatic yoga for FND symptom improvement and interoceptive awareness, supporting progression to a fully powered trial.

Background: Functional seizures (FS) and functional motor symptoms (FMS), subtypes of functional neurological disorder, may involve shared and distinct predisposing, precipitating, perpetuating and triggering (PPPT) factors. This study investigated potential self-reported PPPT factors in FS and FMS separately. Methods: 200 participants (FS=50, FMS=50, individuals with anxiety and/or depression (clinical controls [CC]=50, healthy controls [HC]=50) completed an in-depth medical history interview and online questionnaires to assess potential aetiological factors including traumatic/adverse life events, alexithymia, autistic traits, psychological and physical symptoms, illness perceptions, cognitive-behavioural responses and outcome measures of general functioning and health-related quality of life (HRQoL). Results: Participants with FS more frequently reported traumatic/adverse events and psychopathology (eg, dissociation, posttraumatic stress disorder) as possible illness causes/precipitating factors and sensory symptom triggers, relative to FMS and/or CCs. In contrast, participants with FMS endorsed physical illness causes/precipitating factors and physical activity and emotion-related symptom triggers more frequently than FS and/or CCs. Physical and dissociative symptoms were elevated, alongside reductions in HRQoL and general functioning in FS/FMS compared with CCs/HCs. Greater current, threatening illness-related beliefs/cognitions were disclosed in FS/FMS compared with CCs. Negative associations between HRQoL, cognitive-behavioural responses and traumatic/adverse events were also seen in FS/FMS. Conclusions: Traumatic events and psychopathology may be more prominently involved in the development/maintenance of FS and physical illness/injury, physical functioning and alexithymia may be more central to FMS. Unhelpful illness-related beliefs and impacts on HRQoL and general functioning are shared between these subtypes. The results of this study provide insight into potential unique and overlapping characteristics of FS/FMS, with implications for treatment.

Introduction: Evidence suggests that dissociation may play a role in the manifestation of functional neurological disorder (FND). Dissociative experiences are frequently reported in FND, yet their dynamic associations with affective and physiological states remain underexplored. This pilot study aimed to examine dissociative symptoms in daily life in FND, to identify predictors of dissociation using ecological momentary assessment (EMA) combined with wearable heart-rate monitoring. Methods: Seventeen individuals with FND (functional seizures/motor symptoms) and seventeen age- and gender-matched healthy controls completed EMA via pseudorandom smartphone prompts eight times daily for one week. This was a secondary analysis of data from a pilot case-control intensive longitudinal observation study. Dissociation (depersonalisation, derealisation, amnesia), negative affect, and subjective arousal were assessed using items modified from validated scales, while heart-rate was continuously recorded via Fitbit devices. Multilevel modelling was conducted to examine between-group differences, and momentary associations between predictors (negative affect, subjective arousal, heart-rate) and dissociative symptoms within the FND group. Time-lagged analyses explored temporal relationships between the predictors and dissociative symptoms. Results: The FND group reported significantly higher dissociative symptoms across the week compared to controls; amnesia (F(1,34)=13.09, p <.001), depersonalisation (F(1, 34)=7.35, p = .010), and derealisation (F(1, 34)=8.31, p = .007), these differences withstood correction for anxiety, but not for depression. Negative affect ( p-values =p-values =p-values = 0.01-0.006, β= 0.078-0.091) were each significant concurrent predictors of all three dissociative symptom types. In combined models, negative affect and subjective arousal remained robust predictors across all symptom domains, whereas heart-rate lost significance. Time-lagged analyses did not yield significant associations. Conclusion: Individuals with FND self-reported elevated dissociative symptoms in daily life compared to healthy controls; however, these significant differences did not remain when controlling for depression. Dissociation was consistently associated with subjective arousal and negative affect, but not heart-rate, underscoring the importance of subjective emotional states over physiological influences on self-reported dissociative symptom variability. The absence of temporal effects highlights the transient nature of dissociation in FND. These findings support the possibility of conceptualising FND through a dissociative lens and emphasise the need for larger longitudinal studies to clarify underlying mechanisms.

Previous research has indicated possible implications for altered interoceptive processing in functional neurological disorder. This study investigated dimensions of interoception in functional seizures (FS, n=50) and functional motor symptoms (FMS, n=50) relative to healthy (HC, n=50) and clinical controls with anxiety disorders/depression (CC, n=50), before and after a physiological autonomic arousal induction (isometric hand-grip). Measures of cardiac interoceptive accuracy and insight (heartbeat tracking task [HTT] with confidence ratings) and in-the-moment ratings of functional neurological symptoms (FNS) were completed pre/post-arousal induction. Baseline interoceptive sensibility (Multidimensional Assessment of Interoceptive Awareness-2) was altered in FS/FMS relative to HC/CC (ps<.004, η2>.07) across ‘Not-Distracting,’ ‘Not-Worrying,’ ‘Attention-Regulation,’ ‘Self- Regulation,’ and ‘Trusting’ subscales. There were no baseline group differences in interoceptive accuracy, confidence, or insight (ps>.13, η2<.05) and no change in FNS (FS/FMS), interoceptive accuracy, or confidence (all groups) post-arousal induction. This study replicates reports of altered interoceptive sensibility alongside intact interoceptive accuracy in FND.

Background: Cognitive symptoms are common in functional neurological disorder (FND), yet evidence of impaired neurocognitive test performance is variable. We aimed to assess self-reported cognitive symptoms, neurocognitive test performance, and metacognitive confidence in patients with functional seizures (FS) and functional motor symptoms (FMS). Methods: Participants with FS (n = 50) and FMS (n = 50) were compared to age- and gender-matched healthy controls (HC, n = 50), and clinical controls with depression and/or anxiety disorders (CC, n = 50). The Cambridge Neuropsychological Test Automated Battery was used to examine response speed, working memory, executive functions, and social–emotional processing, with subjective confidence rated for each test. Intellectual functioning, performance validity, and self-reported cognitive symptoms were also assessed. Results: The FND groups reported elevated cognitive symptoms compared to HC and CC (p-values<0.001). Impaired performance was demonstrated in both FND groups on tests of sustained attention (p-values = 0.03- < 0.001) and set-shifting (p-values = 0.01–0.001). Performance validity was comparable between groups (p = 0.64). The FND groups reported reduced post-diction confidence for sustained attention (p < 0.001). Executive performance deficits correlated with reduced test-specific confidence in FS/FMS (p-values = 0.02- < 0.001). In FMS, post-diction confidence for sustained attention performance correlated negatively with cognitive symptoms (p = 0.002). Cognitive symptoms were associated with psychological/physical symptom load, quality-of-life, and/or general functioning in FND and CC groups (p-values = 0.04- < 0.001). Conclusions: Patients with FS and FMS displayed localized deficits on tests of executive functioning, with reduced domain-specific metacognitive confidence, alongside significant cognitive symptoms. These neurocognitive features were associated with poorer clinical status, warranting interventions targeting cognitive control and/or cognitive symptoms in everyday life.

Introduction: Evidence suggests that dissociation may play a role in the manifestation of functional neurological disorder (FND). Dissociative experiences are frequently reported in FND, yet their dynamic associations with affective and physiological states remain underexplored. This study aimed to examine dissociative symptoms in daily life in FND, to identify predictors of dissociation using ecological momentary assessment (EMA) combined with wearable heart-rate monitoring.Methods: Seventeen individuals with FND (functional seizures/motor symptoms) and seventeen age- and gender-matched healthy controls completed EMA via pseudorandom smartphone prompts eight times daily for one week. Dissociation (depersonalisation, derealisation, amnesia), negative affect, and subjective arousal were assessed using items modified from validated scales, while heart-rate was continuously recorded via Fitbit devices. Data were aggregated at week-level for between-group comparisons and analysed using Mann-Whitney U tests. Multilevel modelling was conducted to examine momentary associations between predictors (negative affect, subjective arousal, heart-rate) and dissociative symptoms within the FND group. Time-lagged analyses explored temporal relationships between the predictors and dissociative symptoms.Results: The FND group reported significantly higher dissociative symptoms across the week compared to controls: amnesia (U=63, p=0.004), depersonalisation (U=63.5, p=0.004), and derealisation (U=84, p=0.034). Effect sizes were moderate-large for amnesia and depersonalisation (r=0.56), and small-moderate for derealisation (r=0.42). Negative affect (p-values=<0.001, β=0.094-0.111), subjective arousal (p-values=<0.001, β=0.102-0.124), and heart-rate (p-values=0.01-0.006, β= 0.078-0.091) were each significant concurrent predictors of all three dissociative symptom types. In combined models, negative affect and subjective arousal remained robust predictors across all symptom domains, whereas heart-rate lost significance. Time-lagged analyses did not yield significant associations.Conclusion: Individuals with FND report elevated dissociative symptoms compared to healthy controls. Dissociation was consistently associated with subjective arousal and negative affect, but not heart-rate, underscoring the importance of subjective emotional states over physiological influences on dissociative symptom variability. The absence of temporal effects highlights the transient nature of dissociation in FND. These findings support conceptualising FND through a dissociative lens and emphasise the need for larger longitudinal studies to clarify mechanisms and inform tailored interventions.