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Pleasure of losing weight, not fear of gaining weight may explain anorexia nervosa

Anorexia nervosa may be associated with pleasure of losing weight, rather than the fear of gaining weight, according to recent findings.

“Recent studies support the idea that [anorexia nervosa] could be the consequence of aberrant reward processing and, combined with exaggerated control, could involve neural circuits implicated in reward processing and compulsivity,” the researchers wrote. “Altered patterns of brain activity associated with emotional and reward processing tasks, related to more or less specific stimuli of the illness, have provided important information about the mechanisms underlying [anorexia nervosa] symptoms.”

To assess the rewarding emotional response to starvation among individuals with eating disorders, researchers measured frequency and amplitude of skin conductance response among 71 females with anorexia nervosa and 20 healthy controls when viewing images of underweight, normal weight and overweight individuals.

Participants with anorexia nervosa exhibited more positive feelings during processing of underweight stimuli and more negative feelings for normal and overweight stimuli.

Skin conductance response indicated a group effect (P < .007), with an overall higher frequency of response among participants with anorexia nervosa.

Skin conductance response was more frequent during processing of underweight stimuli, compared with normal and overweight stimuli.

The Met allele of the BDNF gene was not more common in participants with anorexia nervosa, compared with controls. However, it was associated with an increased frequency of skin conductance response to cues for starvation (P = .008).

“A higher positive value of starvation, rather than more negative value of overweight, might more accurately define patients with [anorexia nervosa]. The Met allele of the BDNF gene could partly mediate the observed higher reward value of starvation in [anorexia nervosa] patients. Disturbed processes of emotional and reward response to starvation may thus promote strategies for maintaining pathological behaviors in patients with [anorexia nervosa],” the researchers concluded. – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.