Exploring Lobar Gray Matter Volume in Women with Current and Lifetime Anorexia Nervosa and Atypical Anorexia Nervosa

Atypical anorexia nervosa (AT-AN) is a variant of anorexia nervosa (AN) where individuals remain at or above a BMI of 18.5 kg/m^2 despite restriction. Our recent research suggests lower gray matter volume (GMV) in frontal, temporal, and parietal areas in adolescents with AN and AT-AN compared to healthy controls. However, past analyses were limited, focusing only on acute weight presentation. This study investigates differences in GMV between females with AN and AT-AN, considering both acute and historic weights.
Structural MRI data from 67 females (14-35y) were processed using Freesurfer to extract GMV of lobes and cortical regions of interest (ROI). Subjects were diagnosed with current AN or AT-AN based on DSM-V-TR criteria. A lifetime diagnosis was created to re-classify individuals into lifetime AN or AT-AN based on self-reported lifetime BMI. Primary analyses used linear mixed effect models to compare group differences in lobar GMV, with secondary ROI analyses conducted for significant lobes.
BMI was significantly lower in current (p<0.01) and lifetime (p<0.01) AN vs AT-AN. Primary analyses revealed significantly lower GMV in the frontal lobe in AN vs AT-AN for current (FDR=0.04) and lifetime (FDR=0.04) groups. ROI-based analyses within the frontal lobe were not significant. We observed lower GMV in the frontal lobe of individuals with AN vs AT-AN for current and lifetime diagnoses. This suggests frontal lobe deficits may be unique to AN and sensitive to low-weight status, implying the potential relevance of executive functions in the disorder. These neurobiological alterations should be further explored through prospective longitudinal analyses.