Supplementary Material for: Interoceptive and affective alterations in Body Integrity Dysphoria: An online self-reporting study

Introduction: Body Integrity Dysphoria (BID) is a rare condition in which individuals experience a long-lasting desire to achieve a specific physical disability. In this study, we tested the hypothesis of interoceptive and affective abnormalities in BID, in line with the evidence of structural and functional alteration of the interoceptive-affective neural system in these individuals. Method: Our study involved 68 participants with BID (mean age 35.6, SD 16.4). Among these participants, 47 expressed a desire for amputation, 14 desired paralysis, 3 sought sensory deprivation, and 3 desired a combination of these forms. For comparisons, we recruited a control group of 79 participants (mean age 35.2, SD 15.8). We administered assessment measures to investigate alexithymia level (TAS-20), disgust sensitivity (DS-R), interoceptive awareness (MAIA-2), and (affective and cognitive) empathy (QCAE). We also administered the Short Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) to identify psychiatric comorbidities. Subgroups with Low O-LIFE scores (BID=31; Controls=43) and subgroups with High O-LIFE scores (BID=37; Controls=36) were derived through a median-split procedure. Results: Within the BID Low O-LIFE group, we found reduced interoceptive sensibility, reduced disgust sensitivity, and increased difficulty in identifying feelings, which refers to a dimension of the alexithymia trait. Within the BID High O-LIFE group, we observed a reduced disgust sensitivity and interoceptive sensibility, accompanied by a diminished score in cognitive empathy. Conclusion: Our study suggests that BID can be associated with altered interoceptive and affective processing.