Spatial orientation constancy is impaired in anorexia nervosa.

In anorexia nervosa (AN), body distortions have been associated with parietal cortex (PC) dysfunction. The PC is also the anatomical substrate of a supramodal reference framework involved in spatial orientation constancy. Given the impaired spatial orientation constancy found in hemineglect, we sought to determine whether similar disturbances could be observed in anorexic patients. We investigated the effect of passive lateral body inclination on the tactile subjective vertical (SV). Fifty participants (25 AN patients and 25 healthy controls) were asked to manually set a rod into the vertical position under three postural conditions. For tilted conditions, we observed a significant deviation of the tactile SV towards the body. This effect was abnormally accentuated in AN patients and might be caused by higher weighting with respect to the egocentric frame of reference. Our findings reinforce the role of the PC in AN and suggest that this dysfunction affects spatial orientation constancy as well as body boundaries.