Looking At Anorexia Nervosa in a New Way

Newer global approaches search for neurobiological causes

Anorexia nervosa still has one of the highest mortality rates among psychiatric disorders, up to 4% among females and 1.3% among males (Curr Opin Psychiatry. 2021. 34:515).  Eating disorders are likely underreported and undertreated, especially in men, which can skew the statistics, leading to underestimates of mortality. Another challenge is that AN mortality rates are often calculated based on individuals in treatment, which likely gives the same effect.

Relapse is common, and no ideal treatment has been found. Two long-term follow-up studies of 22 and 30 years revealed some positive results, although 1 in 5 patients still had chronic disease after 22 years (J Clin Psychiatry. 2017. 78:184; Br J Psychiatry. 2020. 216:97). And, in the 30-year follow-up, only 64% of patients with AN had fully recovered. There were no deaths, and although some individuals had been free from an eating disorder for 10 or 20 years, late relapses did occur.

A new approach to AN and other eating disorders will use identification of suspect genes and the biology of the gut to solve some of challenges posed by AN diagnosis and treatment.

International Groups Pursue a Genetic Cause for AN

Dr. Cynthia M. Bulik, founding director of the University of North Carolina Center for Excellence for Eating Disorders, Chapel Hill, and her colleagues are working to analyze the genetics and intestinal microbiota of patients with AN (Nat. Neurosci. 2022. 25:543; Psychiatry Clin Neurosci. 2019. 73:518). They are exploring possible biologic pathways for the development and outcome of AN. The hope is that the studies will stimulate development of pharmacologic agents that will target the core biology of AN, as well as that of patients with bulimia nervosa (BN) and binge eating disorder (BED). Evaluating the complex microbiota of the gut (intestinal microbiota) underlying biological mechanisms may give new insight into extreme weight dysregulation and new “points of entry for AN treatment,” according to the authors.

The Eating Disorders Genetics Initiative, or EDGI, is an ongoing global research study on the genetics of eating disorders. The initiative is currently the largest-ever research study of genetic and environmental causes of eating disorders. The goal is to identify hundreds of genes that influence the risk of developing AN, BN, and BED. (Website: edgi@unc.edu)

Duration of illness and age as predictors of outcome

Meanwhile, valuable work using more traditional research continues. Dr. Adrian Meule and colleagues at several German hospitals are comparing the duration of illness and age as predictors of short-term treatment outcome. They recruited 902 female inpatients aged 12 to 73 with AN for the study (Eat Disord. 2022. Sept 30; 1-11. Published online ahead of print).

Patients who had AN for longer periods gained less weight, had smaller improvements in global functioning, and smaller decreases in self-reported eating disorder symptoms. However, the length of illness almost perfectly correlated with the patients’ ages. The results suggest that having AN for a longer period does indeed relate to worse short-term treatment outcome among inpatients with AN.

The authors’ findings further support that weight suppression is a robust predictor of weight gain in addition to–and in interaction with–current body weight. As weight suppression can easily be assessed at admission, the authors suggest weight suppression may help to anticipate treatment course and outcome in patients with AN (J Psychosom Res. 2022. doi: 10.1016/j.jpsychores.2022.110924).

These findings are important for how we think about “severe and enduring AN.” Efforts to link duration to outcome have been mixed, but in this large study there was some relationship between length of illness and poorer outcome.

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