Behavioral Responses to Uncertainty in Weight-Restored Anorexia Nervosa – Preliminary Results

Impaired decision-making under conditions of uncertainty seems to contribute to theexpression and maintenance of anorexia nervosa (AN), but it is not clear whether thisimpairment is a disease state that would remit with treatment, or a persisting trait inpatients with AN. To examine this question, a longitudinal study was conducted in12 female inpatients with AN (age M = 22.2, SE = 1.36), before (Time-1) and afterreaching a body mass index of >17.5 kg/m2 (Time-2). Intolerance of uncertainty (IU)was assessed via a decision-making task, the wheel of fortune (WOF). Weight gain atTime-2 was accompanied with significant changes in uncertainty-related performancecompared to Time-1 [(Time Uncertainty), p < 0.05]. At Time-1, reaction times (RTs)varied in function of uncertainty, while at Time-2, uncertainty did not modulate RTs.These findings support a change in decision-making under uncertainty with successfulweight-rehabilitation in AN. While IU was present in underweight patients, it becamenon-significant after weight restoration

Lifetime Weight Characteristics of Adult Inpatients With Severe Anorexia Nervosa: Maximal Lifetime BMI Predicts Treatment Outcome

Background: The body mass index is a key predictor of treatment outcome in patients with anorexia nervosa. In adolescents, higher premorbid BMI is a strong predictor of a favorable treatment outcome. It is unclear whether this relationship holds true for adults with anorexia nervosa. Here, we examine adult patients with AN and investigate the lowest and highest lifetime BMI and weight suppression as predisposing factors for treatment outcome. Methods: We included 107 patients aged 17-56 with anorexia nervosa and tracked their BMI from admission to inpatient treatment, through discharge, to follow-up at 1-6 years. Illness history, including lowest and highest lifetime BMI were assessed prior to admission. We used multiple linear regression models with minimal or maximal lifetime BMI or weight suppression at admission as independent variables to predict BMI at admission, discharge and follow-up, while controlling for patients' age, sex, and duration of illness. Results: Low minimal BMI had a negative influence on the weight at admission, which in turn resulted in a lower BMI at discharge. Higher maximal BMI had a substantial positive influence on BMI at discharge and follow-up. Weight suppression was highly correlated with maximal BMI and showed similar effects to maximal BMI. Conclusion: Our findings strongly support a relationship between low minimal lifetime BMI and lower BMI at admission, and between higher maximal lifetime BMI or weight suppression and a positive treatment outcome, even years after discharge. Overall, maximal BMI emerged as the most important factor in predicting the weight course in adults with AN. Keywords: anorexia nervosa; hospitalization; treatment outcome; weight characteristics; weight suppression

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. Keywords: BMI; Cortical thickness; MRI; Subcortical volume; Surface are