Researchers within the ENIGMA Eating Disorders Working Group published a case-control study identifying structural brain features linked to bulimia nervosa, finding that affected individuals exhibit reduced nucleus accumbens volume and reduced temporal cortical surface area compared to healthy controls. Led by LA Berner and colleagues, the analysis utilized three-dimensional T1-weighted MRI scans and clinical data from seventeen cohorts across thirteen international sites, with findings published in JAMA Psychiatry.
MRI Analysis Across Seventeen International Cohorts
The study analyzed data gathered between February 2022 and October 2025. Investigators examined a sample of 786 female participants, which included 369 individuals diagnosed with bulimia nervosa and 417 healthy controls. Participants had a mean age of 23.6 years, spanning an age range from 12.0 to 53.6 years. Standardised ENIGMA pipelines were used to extract regional cortical thickness, surface area, and subcortical volumes from the imaging data.
Bulimia nervosa ranks second among eating disorders in prevalence and disease burden. Historically, reliable brain morphometric features associated with the disorder remained elusive due to neuroimaging studies that produced inconsistent findings across small sample sizes. By pooling data across seventeen cohorts, the ENIGMA Eating Disorders Working Group sought to overcome past sample size limitations.
Reduced Nucleus Accumbens and Temporal Cortex Differences
The analysis revealed specific anatomical differences between participants with bulimia nervosa and healthy controls. Individuals with the disorder showed lower nucleus accumbens volume, represented by a Cohen d of -0.20 with a 95% confidence interval ranging from -0.34 to -0.06. Researchers also observed a lower surface area in the superior temporal cortex (d, -0.26; 95% CI, -0.41 to -0.12) and the transverse temporal cortex (d, -0.24; 95% CI, -0.38 to -0.10).
The study found no significant group differences in cortical thickness. Most of the identified anatomical differences remained statistically significant even after researchers adjusted for body mass index (BMI), illness duration, depressive symptoms, psychotropic medication use, and purging behavior.
Symptom Severity and Cortical Surface Area Associations
Binge-eating frequency demonstrated specific anatomical correlates within the data. Higher binge-eating frequency was associated with lower surface area across several regions, including the superior temporal cortex, the insula, and the orbitofrontal cortex, with correlation coefficients ranging from -0.20 to -0.14. Conversely, total compensatory behaviors showed no significant anatomical associations.
These localized structural alterations implicate several neural circuits in the pathophysiology of bulimia nervosa, including reward, cognitive control, interoceptive, and social cognition circuits. The findings advance existing neurobiological models for a condition that has historically lacked clear neuroimaging characterization. Further research is necessary to establish the causal role of these structural features and determine their potential diagnostic utility.