The validity of the fifth and the 10th Body Mass Index percentile as weight cut-offs for anorexia nervosa in adolescence: No evidence from quantitative and network investigation of psychopathology.

OBJECTIVE: Although the fifth Body Mass Index (BMI) percentile is the Diagnostic and Statistic Manual of Mental Disorders -5 weight cut-off criterion to diagnose anorexia nervosa (AN) in children and adolescents, its validity has not been proved, and the 10th percentile value is often applied. We aimed to investigate the diagnostic validity of these weight cut-offs. METHOD: We compared general and eating-disorder (ED) specific psychopathology in 380 adolescents with AN or atypical AN. They were grouped first with respect to the fifth BMI percentile and then with respect to the 10th BMI percentile and differences between groups were analysed. Network analyses on psychopathological symptoms were also conducted. RESULTS: Adolescents with BMI above the fifth and the 10th percentile reported more severe ED specific symptomatology compared to those with BMI below these cut-offs. No significant differences emerged between groups neither in general psychopathology nor in the network structure of psychopathology. CONCLUSIONS: The fifth BMI percentile does not discriminate psychopathology severity in adolescents with AN. From the psychopathology perspective, our findings suggest that adolescents with atypical AN deserve the same clinical and research attention as those with full AN. Future studies are needed to identify a more accurate definition of underweight in adolescents.

Ghrelin response to hedonic eating in underweight and short-term weight restored patients with anorexia nervosa.

Recently, anorexia nervosa (AN) has been conceptualized as a reward-related disorder, and alterations in brain reward processes have been documented in both acute and recovered AN patients. However, the role of endogenous biochemical mediators, such as ghrelin, in the modulation of reward processes has been poorly investigated in this eating disorder. Hedonic eating, that is the consumption of food exclusively for pleasure and not to maintain energy homeostasis, is a useful paradigm to investigate the physiology of food-related reward. Therefore, we assessed the response of peripheral ghrelin to hedonic eating in 7 underweight and 7 recently weight-restored AN patients and compared it to that of previously studied healthy controls. We found that in satiated underweight patients with AN plasma ghrelin levels progressively decreased after the exposure and the consumption of both the favorite and unfavorite food whereas in satiated weight-restored AN patients and satiated healthy controls plasma ghrelin concentrations significantly increased after the exposure to the favorite food and after eating it, but decreased after the unfavorite food. These results suggest a derangement in the ghrelin modulation of food-related pleasurable and rewarding feelings, which might sustain the reduced motivation toward food intake of acute AN patients.