Brain Structure in Acutely Underweight and Partially Weight-Restored Individuals With Anorexia Nervosa: A Coordinated Analysis by the ENIGMA Eating Disorders Working Group.

BACKGROUND: The pattern of structural brain abnormalities in anorexia nervosa (AN) is still not well understood. While several studies report substantial deficits in gray matter volume and cortical thickness in acutely underweight patients, others find no differences, or even increases in patients compared with healthy control subjects. Recent weight regain before scanning may explain some of this heterogeneity. To clarify the extent, magnitude, and dependencies of gray matter changes in AN, we conducted a prospective, coordinated meta-analysis of multicenter neuroimaging data. METHODS: We analyzed T1-weighted structural magnetic resonance imaging scans assessed with standardized methods from 685 female patients with AN and 963 female healthy control subjects across 22 sites worldwide. In addition to a case-control comparison, we conducted a 3-group analysis comparing healthy control subjects with acutely underweight AN patients (n = 466) and partially weight-restored patients in treatment (n = 251). RESULTS: In AN, reductions in cortical thickness, subcortical volumes, and, to a lesser extent, cortical surface area were sizable (Cohen's d up to 0.95), widespread, and colocalized with hub regions. Highlighting the effects of undernutrition, these deficits were associated with lower body mass index in the AN sample and were less pronounced in partially weight-restored patients. CONCLUSIONS: The effect sizes observed for cortical thickness deficits in acute AN are the largest of any psychiatric disorder investigated in the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Consortium to date. These results confirm the importance of considering weight loss and renutrition in biomedical research on AN and underscore the importance of treatment engagement to prevent potentially long-lasting structural brain changes in this population.

Axis-I comorbidity is linked to prospective instability of diagnoses within eating disorders.

BACKGROUND: Eating disorders (ED) are classified into Anorexia Nervosa, Bulimia Nervosa, and eating disorder not otherwise specified. Prospectively, the diagnostic instability within ED is high, but it is not clear which factors may account for this instability. So far, there is no evidence of whether psychiatric comorbidity may play a role in ED diagnostic crossover. We sought to determine possible influences of comorbidities of axis I and II on diagnostic crossover within ED. METHODS: Longitudinal data of 192 female patients were collected. All patients had a diagnosis of a current ED at study entry (baseline, T0). Diagnoses were re-established both 12 months (T1) and 30 months (T2) after T0. Comorbid psychiatric diagnoses were grouped into axis I and axis II according to DSM-IV. RESULTS: Patients with instable ED diagnoses had lifetime axis-I comorbidity more frequently than patients with stable ED diagnoses (χ2 = 4.74, df = 1, p < 0.05). Post-hoc exploratory tests suggested that the effect was mainly driven by affective disorders like major depression. There was no difference for axis-II comorbidity between stable and instable diagnostic profiles. CONCLUSIONS: Following previous reports of diagnostic crossover in ED, the present investigation points to an influence of a life-time psychiatric comorbidity, in particular of axis I, on follow-up diagnoses of ED. Comorbid affective disorders like major depression might facilitate a switching between clinical phenotypes. The understanding of mechanisms and causes of the symptoms fluctuation will be subject of future studies.