Aetiological Factors in Functional Seizures and Functional Motor Symptoms:Shared and Distinct Features

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. <br/>Methods: Two hundred participants (FS=50, FMS=50, individuals with anxiety and/or depression [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). <br/>Results: Participants with FS more frequently reported traumatic/adverse events and psychopathology (e.g., dissociation, PTSD) 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 to CCs/HCs. Greater current, threatening illness-related beliefs/cognitions were disclosed in FS/FMS compared to CCs. Negative associations between HRQoL, cognitive-behavioural responses, and traumatic/adverse events were also seen in FS/FMS. <br/>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.