Anorexia Nervosa: difficulties in body schema representation and motor imagery.

Anorexia nervosa (AN) is a psychiatric disorder where the physical appearance becomes the priority of the person, which shows a strong fear of becoming fat and a distortion of the real body size. Recent investigations have shown that AN is not only a disease related to body image, spatial and motor navigation can also be impaired due to body schema alterations. In the present study, we were focused on studying the body schema, which is the unconscious mental representation of an action. We measure it with tests that are related with the mental simulation of a movement, and we wanted to observe if this mental simulation would be altered considering the body schema of patients suffering from AN. The sample consisted of 52 patients with AN and 62 healthy controls (HC). All participants completed two implicit motor imagery tests, the Mental Rotation with both 3D objects and human figures and the Perspective-taking/Spatial Orientation, and three explicit motor imagery tests, the Test of Ability in Movement Imagery (TAMI), the Mental Chronometry test, and the Vividness of Movement Imagery Questionnaire. It was found that patients with AN show an impairment in the ability to mentally imagine body movements, have greater difficulties in imagining the vividness of a movement when they are asked to use the kinesthetic or internal perspective, have worse accuracy in mentally rotating human figures, and displayed more difficulties than HC in assuming a different visuospatial perspective. Nevertheless, patients with AN and HC show similar results in mentally rotating 3D objects. The obtained results indicate that patients suffering from AN show an alteration in the ability to mentally represent movements.