Lower region‐specific gray matter volume in females with atypical anorexia nervosa and anorexia nervosa

Abstract

ObjectiveFew studies have focused on brain structure in atypical anorexia nervosa (atypical AN). This study investigates differences in gray matter volume (GMV) between females with anorexia nervosa (AN) and atypical AN, and healthy controls (HC).MethodStructural magnetic resonance imaging data were acquired for 37 AN, 23 atypical AN, and 41 HC female participants. Freesurfer was used to extract GMV, cortical thickness, and surface area for six brain lobes and associated cortical regions of interest (ROI). Primary analyses employed linear mixed‐effects models to compare group differences in lobar GMV, followed by secondary analyses on ROIs within significant lobes. We also explored relationships between cortical gray matter and both body mass index (BMI) and symptom severity.ResultsOur primary analyses revealed significant lower GMV in frontal, temporal and parietal areas (FDR < .05) in AN and atypical AN when compared to HC. Lobar GMV comparisons were non‐significant between atypical AN and AN. The parietal lobe exhibited the greatest proportion of affected cortical ROIs in both AN versus HC and atypical AN versus HC. BMI, but not symptom severity, was found to be associated with cortical GMV in the parietal, frontal, temporal, and cingulate lobes. No significant differences were observed in cortical thickness or surface area.DiscussionWe observed lower GMV in frontal, temporal, and parietal areas, when compared to HC, but no differences between AN and atypical AN. This indicates potentially overlapping structural phenotypes between these disorders and evidence of brain changes among those who are not below the clinical underweight threshold.Public significanceDespite individuals with atypical anorexia nervosa presenting above the clinical weight threshold, lower cortical gray matter volume was observed in partial, temporal, and frontal cortices, compared to healthy individuals. No significant differences were found in cortical gray matter volume between anorexia nervosa and atypical anorexia nervosa. This underscores the importance of continuing to assess and target weight gain in clinical care, even for those who are presenting above the low‐weight clinical criteria.

A refined rodent model of anorexia nervosa: Simulating state‐specific effects of caloric restriction and weight restoration

“…Moreover, this relative difference in bodyweights is more representative of clinical AN. For example, in ABA models, AN rodents are often ~35%–45% smaller compared to control animals (Scharner & Stengel, 2021 ), whereas in clinical studies the difference between healthy controls and those with AN typically ranges from 20% to 30% (Keeler et al., 2024 ; Kerruish et al., 2002 ; Lyall et al., 2024 ). Importantly, none of our animals required euthanasia due to excessive weight loss, low body condition score, or dramatic changes in behavior.…”

Time to revisit the definition of atypical anorexia nervosa

“…Despite not being underweight, individuals with atypical AN can also develop structural brain changes similar to those seen in AN. Using structural magnetic imaging, Lyall et al (2024) found that gray matter volumes in the frontal, temporal, and parietal areas were lower than healthy controls in both atypical AN and AN, with no significant differences between atypical AN and AN. In a large cohort of adults hospitalized for medical instability, Gibson et al (2024) found that both weight suppression and recent weight loss were predictive of some of the physiological changes of malnutrition, but low BMI better predicted medical complications than either weight suppression or recent weight loss.…”