Neuroanatomical associations with autistic characteristics in those with acute anorexia nervosa and weight-restored individuals

Common neuroanatomical regions are associated with both states of anorexia nervosa (AN) and autistic characteristics, but restoration of body mass index (BMI) has been associated with decreased presentation of autistic characteristics in some individuals with AN. This study aims to examine neuroanatomical correlates associated with autistic characteristics in those with acute anorexia nervosa (ac-AN) and those previously diagnosed with AN but whose weight has been restored (WR). In total, 183 individuals (healthy controls [HCs] = 67; n[ac-AN] = 68; n[WR] = 48) from the Brain imaging of Emotion And Cognition of adolescents with Anorexia Nervosa (BEACON) study were included, with autistic characteristics determined in both ac-AN and WR individuals (n = 116). To further examine BMI, ac-AN and WR group associations were compared. Random forest regression (RFR) models examined whether autistic characteristics and morphology of the anterior cingulate cortex (ACC), middle frontal gyrus (MFG), and orbitofrontal cortex (OFC) were able to predict future levels of social anhedonia and alexithymia. Group-wise differences were identified within the volume and surface area of the MFG and OFC, which were unrelated to BMI. Autistic characteristics were inversely associated with MFG and ACC volume, with differences in associations between ac-AN and WR groups seen in the surface area of the MFG. RFR models identified moderate-to-weak performance and found that autistic characteristics were not important predictive features in a priori and exploratory models. Findings suggest that the presence of autistic characteristics in those with ac-AN are associated with the volume of the MFG and are unrelated to BMI restoration.