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Objectives/AimsAltered interoception may be a core pathophysiological mechanism in functional neurological disorder (FND). However, there have been inconsistent findings from interoceptive accuracy paradigms, with several studies reporting no significant group differences in comparisons to controls when tested at rest/baseline. This is contrary to evidence for alterations in other interoceptive dimensions including awareness (metacognitive evaluation of interoceptive accuracy) and sensibility (self- reported sensitivity to bodily sensations) in this population. We aimed to measure interoception across several dimensions, with the prediction that individuals with FND would show reduced accuracy, awareness, and sensibility compared to controls.MethodsIndividuals with FND (n=17, 13F:4M, 10 motor symptoms, 7 motor/seizures) and healthy controls (HC, n=17, 13F:4M) completed measures of interoceptive accuracy and awareness (modified heartbeat tracking task [HTT]) and a time estimation task (TET). Participants also completed a validated scale of interoceptive sensibility (Multidimensional Assessment of Interoceptive Awareness-2, MAIA-2).ResultsThe groups were matched for age (p=.51), sex (p=1.00), and body mass index (p=.19). FND and HC groups did not differ in interoceptive accuracy (p=1.00) or awareness (p=.99), although the FND group displayed lower scores on the ‘Not- Distracting’ (p<.001, g=1.42) and ‘Trusting’ (p=.005, g=1.17) subscales of the MAIA-2, relative to controls. There was no relationship in either group between HTT and TET scores. There was a significant positive relationship between HTT accuracy and awareness (confidence) in the control group (r=.61, p=.016) but not in the FND group (r=.11, p=.69). Exploratory correlations revealed a significant positive relationship between interoceptive awareness and the ‘Self-Regulation’ subscale of the MAIA-2 in the FND group (r=.77, p=.002).ConclusionsIndividuals with FND did not differ from HCs on interoceptive accuracy or awareness, measured at rest. The lower levels of ‘Not-Distracting’ and ‘Trusting’ seen in this FND sample replicated our previous study, suggesting that there may be a separation between trait and state interoceptive awareness in FND, reinforcing the need for interoception to be considered within a multidimensional framework. The lack of relationship between interoceptive accuracy and awareness in the FND group also implies that there may be a disconnect between actual performance and subjective confidence. Our future work will explore the possibility that interoceptive impairments in FND may be state dependent, measuring these interoceptive domains with other paradigms, in larger samples, compared to both healthy and clinical controls.

Objectives/AimsBiopsychosocial perspectives have highlighted the multifactorial and diverse aetiology of functional neurological disorder (FND). We aimed to assess a range of potential predisposing, precipitating and perpetuating factors in FND, and to explore relationships between aetiological factors and current functioning or health-related quality- of-life (HRQoL).MethodsSeventeen participants with FND (motor symptoms and/or seizures) and 17 healthy controls (HCs) underwent an in-depth interview and completed validated questionnaires, including the Traumatic Experiences Checklist (TEC), Toronto Alexithymia Scale-20, Multiscale Dissociation Inventory, Somatoform Dissociation Questionnaire-20, Autistic Spectrum Quotient, Patient Health Questionnaire-9 and -15, Generalised Anxiety Disorder-7, Brief Illness Perception Questionnaire (B-IPQ), Short Form Survey-36 (SF-36) and the Work & Social Adjustment Scale.ResultsThe groups did not differ in sex (p=1.00) or age (p=.51). The most commonly reported FND symptom precipitants were physical activity/exertion (59%), stress/emotion (59%), sensory (47%) and fatigue (41%). Perceived causes of FND (B-IPQ) were physical (e.g., injury, illness, 65%), stress/emotions (53%), psychosocial trauma (47%) and work-related (29%). There was a trend towards higher rates of adverse life events (TEC) in the FND group compared to HCs (p=.06), and the FND group reported greater impact of events (p=.03). The most frequent adverse experiences in the FND group were: looking after parents/siblings as a child (41%), family problems (41%), parental divorce (41%), intense pain (41%), emotional neglect (41%), and sexual abuse (non-familial, 41%). The most common adverse experiences in HCs were: bereavement (35%) and parental divorce (41%). The FND group had higher scores for alexithymia (p=.002), somatoform dissociation (p<.001), aspects of psychological dissociation (disengagement p=.003, depersonalisation p=.001, derealisation p=.002, memory disturbance p=.01), anxiety (p<.001), depression (p<.001), and physical symptoms (p<.001). No significant differences were observed for autistic spectrum traits (p=.22) and some types of psychological dissociation (emotional constriction p=.38, identity disturbance p=.17). FND participants reported worse HRQoL than HCs in all SF-36 domains (p-values .01- <.001). Work/social functioning was impaired in the FND group relative to HCs (p<.001). Poorer work/social functioning was associated with higher depression scores (p=.016). Worse HRQoL in several domains was associated with higher somatoform dissociation and/or anxiety scores (p-values .044-.005). Lower general health HRQoL scores were associated with higher TEC total (p=.020) and impact (p=.011) scores.ConclusionsIndividuals with FND report diverse aetiological factors, including psychosocial, physical and environmental stressors. Alexithymia, dissociative tendencies, emotional distress, and physical symptom burden are also possible predisposing and/or perpetuating factors. Somatoform dissociation, anxiety and adverse experiences may be related to HRQoL in FND.

BackgroundDifferences in affective processing have previously been shown in functional neurological disorder (FND); however, the mechanistic relevance is uncertain. We tested the hypotheses that highly arousing affective stimulation would result in elevated subjective functional neurological symptoms (FNS), and this would be associated with elevated autonomic reactivity. The possible influence of cognitive detachment was also explored.MethodIndividuals diagnosed with FND (motor symptoms/seizures; n=14) and healthy controls (n=14) viewed Positive, Negative and Neutral images in blocks, while passively observing the stimuli (‘Watch’) or detaching themselves (‘Distance’). The FND group rated their primary FNS, and all participants rated subjective physical (arousal, pain, fatigue) and psychological states (positive/negative affect, dissociation), immediately after each block. Skin conductance (SC) and heart rate (HR) were monitored continuously.ResultsFNS ratings were higher after Negative compared with Positive and Neutral blocks in the FND group (p=0.002, ηp 2=0.386); however, this effect was diminished in the Distance condition relative to the Watch condition (p=0.018, ηp 2=0.267). SC and/or HR correlated with FNS ratings in the Negative-Watch and Neutral-Distance conditions (r values=0.527–0.672, p values=0.006–0.035). The groups did not differ in subjective affect or perceived arousal (p values=0.541–0.919, ηp 2=<0.001–0.015).ConclusionsEmotionally significant events may exert an influence on FNS which is related to autonomic activation rather than altered subjective affect or perceived arousal. This influence may be modulated by cognitive detachment. Further work is needed to determine the relevance and neural bases of these processes in specific FND phenotypes.