Exploring three levels of interoception in people with functional motor disorders

Introduction: A three-level model of interoception has recently been defined. We aim to study the interoceptive processing in individuals with functional motor disorder (FMD). Methods: Twenty-two patients with FMD were compared to 23 healthy controls. They underwent a protocol measuring different levels of interoception including: accuracy (a heart-beat tracking task), awareness (participant's confidence level) and sensibility (the Body Awareness Questionnaire-BAQ). Depression, anxiety and alexithymia were assessed by means of validated clinical scales. Results: The FMD group showed a lower cardiac interoceptive accuracy and sensibility than healthy controls but they did not differ in terms of awareness (p = 0.03 and 0.005 respectively). They were aware of their poor performance in the accuracy task. Cardiac interoceptive accuracy positively correlated with the BAQ sub-scales "Predict Body Reaction" (r = 0.49, p = 0.001) and "Sleep-Wake Cycle" (r = 0.52, p < 0.001). A mediation analysis showed a significant indirect effect of group on cardiac interoceptive accuracy through BAQ "Predict Body Reaction" (b = -2.95, 95% BCa CI[-7.2;-0.2]). The direct effect of group on "Predict Body Reaction" was still significant (b = - 6.95, p = 0.02, 95% CI[-13.18;-0.73]). Conclusions: People with FMD have impaired cardiac interoceptive accuracy and sensibility but no difference in metacognitive interoception compared to healthy controls.