A genetic polymorphism was targeted in a French study.
Reprinted from Eating Disorders Review
July/August Volume 27, Number 4
Researchers at INSERM (the French Institute of Health and Medicine), Descartes University, and Sainte Anne Hospital, Paris, have published a paper supporting the idea that the main emotion that drives weight loss in anorexia nervosa (AN) isn’t fear of fat, one of the three main criteria for a diagnosis of AN. Instead, the driving force is pleasure at losing weight, according to the authors (Transl Psychiatry. 2016; 6:e829).
The researchers used a skin conductance test, which measures perspiration rate when exposed to various images, in a group of 70 patients with AN and 70 healthy controls. Seventy female AN patients viewed images of people who were of normal weight, underweight, or overweight. When the patients viewed images of normal weight or overweight persons, their reactions were the same as those reported in a control group. However, when they viewed images of thin individuals, they had enhanced responses versus those of the healthy control subjects.
The French scientists then assessed the role of the Val66Met BDNF polymorphism as a potential intermediate factor (also see earlier article, “Neurobiological Clues to Anorexia Nervosa”). This polymorphism occurred at similar rates in the AN and normal controls, but elevated skin conductance was more common in the group with the val66met allele. The authors concluded that the val66met allele of the BDNF gene may be related to the rewarding value of restriction in patients with AN.