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

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Abstract
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.