Negative evaluations of the own body, body shape, or body weight and the associated body dissatisfaction have a negative influence on quality of life and self-esteem and are one of the most important risk factors for the development of eating disorders. People with bulimia nervosa are seriously affected by this body dissatisfaction. Because their self-evaluation is largely determined by their body shape or weight, they strive for a perfect body. This disorder is mainly diagnosed in women. Body image disturbances are a core feature of bulimia nervosa; body dissatisfaction is however also common in women without eating disorders. Research shows that body-related fears can be decreased by the repetitive confrontation with the own body; however, in many cases body dissatisfaction is still high, even after body confrontation. For this reason, current psychotherapeutic interventions have to focus more on the mechanisms contributing to the maintenance of body dissatisfaction in bulimia nervosa. Furthermore, also women with high body dissatisfaction who do not suffer from an eating disorder could benefit from this kind of intervention by learning to accept themselves and their body and thus become more satisfied.

Transcranial direct current stimulation (tDCS) is a non-invasive method, which allows us to influence the activity of the cerebral cortex. Experimental studies in humans have shown that tDCS can improve cognitive control and information processing, i.e. attention, but also memory functions. This is relevant for the current study since many studies in the domain of body dissatisfaction could show that attentional processes play a major role in the processing of body image.

The main objective of this study is to investigate the effects of tDCS on the emotional processing of the own body. To this aim, a group of women with a diagnosis of bulimia nervosa will be compared to a group of women without this diagnosis by use of a combined eye-tracking and electroencephalogram (EEG) paradigm, as well as a near infrared spectroscopy (NIRS) paradigm. Following, only participants with bulimia nervosa or with strong body dissatisfaction are offered a training of 12 sessions, where they are repeatedly confronted with pictures of their own body; at the same time, participants receive either active or sham tDCS. After the last training session, emotional processing of the body image will be assessed once more through experimental paradigms. Body dissatisfaction is assessed through questionnaires, before the experimental paradigms, after the training sessions, and at 4-week and 3-months follow up.

Women with and without bulimia nervosa are needed for participation in this study.