AN INTERNATIONAL ENIGMA Eating Disorders Working Group analysis has identified structural brain morphometric features linked to bulimia nervosa, revealing that reduced nucleus accumbens volume and reduced temporal cortical surface area distinguish affected individuals from healthy controls.
Bulimia nervosa ranks second among eating disorders in prevalence and disease burden, yet reliable brain morphometric features associated with the disorder have remained elusive. Progress has been limited by neuroimaging studies with inconsistent findings across small samples.
Researchers conducted a case-control study using three-dimensional T1-weighted MRI and clinical data from thirteen international sites comprising seventeen cohorts within the ENIGMA Eating Disorders Working Group. Data were analysed between February 2022 and October 2025.
The sample included 786 female participants: 369 with bulimia nervosa and 417 healthy controls, with a mean age of 23.6 years (range, 12.0 to 53.6). Regional cortical thickness, surface area, and subcortical volumes were extracted using standardised ENIGMA pipelines.
Compared with controls, participants with bulimia nervosa had lower nucleus accumbens volume (Cohen d, -0.20; 95% CI, -0.34 to -0.06), lower surface area of the superior temporal cortex (d, -0.26; 95% CI, -0.41 to -0.12), and lower surface area of the transverse temporal cortex (d, -0.24; 95% CI, -0.38 to -0.10). No significant group differences in cortical thickness were observed.
Most differences remained significant after adjustment for BMI, illness duration, depressive symptoms, psychotropic medication use, and purging behaviour.
Binge-eating frequency was associated with lower surface area across several regions, including the superior temporal cortex, insula, and orbitofrontal cortex (r range, -0.20 to -0.14), while total compensatory behaviours showed no significant anatomical associations.
These findings have identified localised structural brain alterations, primarily in cortical surface area, that are associated with bulimia nervosa, offering some of the first reliable brain morphometric features for the disorder.
The results implicate reward, cognitive control, interoceptive, and social cognition circuits in its pathophysiology, advancing neurobiological models of a condition whose brain basis has remained poorly characterised. Further research is needed to clarify these features’ causal role and diagnostic potential.
Reference
Berner LA et al. Structural brain correlates of bulimia nervosa diagnosis and symptom severity: a coordinated ENIGMA eating disorders working group analysis. JAMA Psychiatry. 2026;DOI:10.1001/jamapsychiatry.2026.2842
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