Abstract
BACKGROUND: A previous case series showed that Nocebo Hypothesis Cognitive Behavioral Therapy (NH-CBT) is a promising treatment for Functional Neurological Symptom Disorder (FNSD). OBJECTIVES: To further evaluate the potential efficacy of NH-CBT in participants with FNSD (motor type). METHODS: This phase IIb pilot, randomized, parallel group trial compared the efficacy of NH-CBT (n = 20) with an active control condition (n = 19). Self-report scales of motor and other physical symptoms, psychological variables, and blinded assessor ratings of participants' mobility were administered at baseline, and at 8- and 16-week follow-ups. The primary outcome and endpoint of this trial was the Physical Functioning scale of the Short Form-36 Health Questionnaire (SF-36 PF) at the end of treatment. RESULTS: Regarding the primary endpoint (SF-36 at the end of treatment), we did not identify a significant between-group effect (d = 0.21, 95% CI: -0.42-0.84). Significant between-group effects in favor of NH-CBT were identified for several secondary outcomes (motor symptoms: d = 0.67, 95% CI: 0.02-1.32; mobility: d = 0.70, 95% CI: 0.05-1.35; symptom perception "concern": d = 0.66, 95% CI: 0.01-1.31). Changes in outcomes within the NH-CBT group showed large effects (d > 0.80) for the primary outcome (SF-36 PF) and the majority of secondary measures post-treatment. A significantly greater proportion of NH-CBT (85%) than control participants (47%) showed full recovery of motor symptoms (P = 0.013). CONCLUSIONS: NH-CBT resulted in large within-group effects on the primary outcome as well as the majority of secondary measures in the NH-CBT group and a greater proportion of fully recovered participants compared with an active control treatment. These promising findings warrant a definitive trial. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.