Affective evaluation of body images in anorexia nervosa

Anorexia nervosa is characterized by fear of weight gain. This is reflected in amygdala activation during confrontation with distorted photographs of oneself simulating weight gain. In contrast, photographs of emaciated women induce startle attenuation, suggesting a positive valuation of extreme slimness. To combine these findings, we applied an affective startle modulation paradigm containing photos of the participants simulating weight gain and photos simulating weight loss. We assessed eye-blink startle responses via EMG in 20 women with anorexia nervosa (AN; mean age = 25 years; mean BMI = 23) and 20 healthy control women (HC; mean age = 25 years; mean BMI = 23). We were able to replicate affective startle modulation of standard positive, negative, and neutral pictures, except for an absence of startle attenuation for positive pictures in AN. Body images did not modulate the startle response in either group. This was in contrast to the subjective ratings, in which the AN group indicated negative valence and high arousal for distorted body images. The body photographs used in our study emphasized general body shape and it appears that this was not threatening to AN patients. Photos highlighting body details might produce different results. Considering that body image exposure, a frequently used intervention tool for AN, aims at fear reduction through habituation, it is essential to determine which aspects of the body actually elicit fear responses to maximize therapy outcome.