Abstracts

Rationale: The relationships between baseline neuropsychiatric factors and clinical outcome in patients with functional neurological disorder (FND) remain poorly understood. Using a transdiagnostic approach to motor FND, which includes patients with psychogenic non-epileptic seizures (PNES, a.k.a. dissociative seizures), functional movement disorders (FMD), and functional weakness, this pilot prospective study investigated links between predisposing vulnerabilities (risk factors) and clinical outcome. Methods: 34 patients with motor FND (including 15 individuals with PNES) participating in a subspecialty FND Clinic prospectively completed baseline and 6-month follow-up psychometric questionnaires. Univariate screening tests followed by multivariate linear regression analyses were used to investigate neuropsychiatric predictors of 6-month clinical outcome in patients with motor FND. Results: In univariate analyses, individual differences in baseline secure attachment traits (Relationship Scales Questionnaire) and depression (Beck Depression Inventory-II) positively correlated with improved Patient Health Questionnaire-15 (PHQ-15) scores. In a multivariate linear regression analysis adjusting for the interval time between baseline and follow-up data collection, baseline secure attachment (standardized beta=0.46; p=0.009) and depression (standardized beta=0.51; p=0.003) scores independently predicted improvements in PHQ-15 scores across the spectrum of motor FND. 37% of the data variance was explained by the model. In additional analyses, patients with a diagnosis of PNES compared to individuals with other motor FND subtypes showed a trend (p=0.05) towards being negatively associated with 6-month physical health outcomes as measured by the Short Form Health Survey-36. Conclusions: This pilot study provides preliminary evidence that secure attachment and comorbid depression are potential positive prognostic factors for patients participating in the standard of care within a subspecialty FND clinic that integrates neurological and psychiatric approaches. We also show that patients with PNES may have a modestly worse physical health prognosis compared to other motor FND subtypes. Future large-scale, multi-site longitudinal studies are needed to comprehensively investigate neuropsychiatric predictors of treatment response across the spectrum of motor FND, including patients with PNES, functional movement disorders and functional limb weakness.  Funding: D.L.P. was funded by the Sidney R. Baer Jr. Foundation and the MGH Physician-Scientist Development Award.