rTMS and Body Shape Perception (STIMOREX)

Anorexia nervosa (AN) is a frequent, potentially life-threatening eating disorder characterized by a resistance to maintaining body weight at or above a minimally normal weight for age and height, an intense fear of weight gain or being "fat" even though underweight, a loss of menstrual periods in girls and women post-puberty and a disturbance in the experience of body weight or shape. Body weight and shape dissatisfaction is linked to the development, maintenance and relapse of AN. Neuroimaging studies have shown that the inferior parietal cortex is involved in body image perception and less activated in patients with AN compared with healthy subjects. Repetitive transcranial magnetic stimulation (rTMS) is used to modulate cortical excitability, and particularly to increase excitability with high-frequency rTMS. The aim of this study was to investigate the effect of "excitatory" high-frequency rTMS over the "hypoactive" inferior parietal cortex of 54 patients with AN.

This randomized, double-blind, placebo-controlled study will compare effective rTMS (2000 ten-Hz stimulations per session, applied at 90% of the resting motor threshold, with 10 sessions in two weeks) versus placebo rTMS.

Assessments will be performed before rTMS and after the last rTMS session (immediately after, at 15 days and three months). The principal criteria for judgement is a body image satisfaction scale (Boby Shape Questionnaire, BSQ-34). The secondary criteria for judgement are eating behaviour scales (Eating Attitude Test, EAT-40; Bulimia test, BULIT and Eating Disorders Inventory, EDI-2), the Hamilton depression rating scale and Hamilton anxiety rating scale, a quality of life scale (Short-Form Health Survey, SF-36), a body composition analysis using a Dual-energy X-ray absorptiometry and the alpha-MSH autoantibodies levels (biomarker for eating disorders recently described).

Inferior parietal cortex rTMS could not only improve body image perception, but also help in the treatment of eating disorders, allowing weight gain with a decreased anxiety and improving patients' quality of life. Also positive results could have direct therapeutic implications with the possibility to complete regular rTMS sessions, or to implant extradural electrodes for chronic parietal cortex stimulation.