Altered interoceptive sensibility alongside intact cardiac interoceptive accuracy and insight: A case-control study in functional seizures and functional motor symptoms

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.