Keeping the Body in Mind

One of the most relevant clinical symptoms of AN for the cognitive psychologist is the strong distortion of the mental representation of the body [1]. Patients suffering from AN (most of whom are young women) often report feeling fatter and larger than they really are. Even though a slight (<5%) overestimation bias is found in healthy women, the phenomenon is significantly exaggerated in patients suffering from AN [2]. Even when the patient reaches a very low actual body weight, she is never satisfied and still considers herself to be fatter or larger than her internal standard. This illusion is particularly impressive because it persists when the patient looks at her own image in a mirror or crucial in AN because this impairment could counteract the benefits of therapy by increasing the obsessive will to lose weight and thus maintaining restrictive eating behaviours [3]. Even though most of the studies to date have emphasized the presence of a disrupted conscious body image in AN, few authors have suggested the involvement of a body schema distortion in this condition [4,5]. The body schema can be defined as a dynamic sensorimotor representation of the body that initiates and guides actions. It is elicited by actionregardless of whether the latter is imagined, anticipated or executed [6,7]. To test the involvement of the body schema in AN, Guardia et al. [8,9] studied a body ‐scaled action ‐anticipation task in which female patients suffering from AN and healthy control participants had to judge whether or not an aperture was wide enough for them to pass through. The anticipation of body-scaled action was severely impaired in patients with AN; they considered that they could not pass through the aperture, even when it was wide enough. Hence, the patients with AN behaved as if their body was larger than in reality. This observation suggested that body schema disturbance is a core feature of AN. The rapid, massive weight loss in AN may be responsible for the mental overestimation of the body schema [10]. The patient may feel that she is locked into the body she had before the disease. Other spatial tasks involving the body schema seem to be also affected. Guardia et al. [11] investigated the effect of passive lateral body inclination on the tactile Subjective Vertical (SV). Fifty participants (25 patients with AN and 25 healthy controls) were asked to manually set a rod into the vertical position under three postural conditions. Under the tilted condition, a significant, abnormal deviation of the tactile SV towards the body was evidenced in the patients with AN. This effect was confirmed in a visual SV task [12] and may have been caused by higher weighting with respect to the egocentric frame of reference. Taken as a whole, these results suggest that body size overestimation in AN is not solely due to psycho-affective factors but also involves impaired neural processing of body dimensions in the parietal networks known to subserve the emergence of body schema. Novel therapies based on both physical exercise and virtual reality [13,14] should focus on the body in general and updating the emaciated body’s new boundaries in particular.