Some authors suggest that Anorexia Nervosa (AN) could be considered as part of the Obsessive Compulsive Spectrum. Obsessive-compulsive disorder (OCD) might be best characterized in terms of failures in cognitive and behavioral inhibitory functions. Impairments in intentionally inhibiting simple motor actions (Response Inhibition) have been demonstrated in these patients but no studies were conducted in AN patients.

The aim of this study was to evaluate Response Inhibition (RI) in patients with Obsessive Compulsive Disorder (OCD), patients with Anorexia Nervosa (AN) and Healthy Controls (HC).

29 HC, 17 patients with OCD and 15 patients with AN were recruited. Stop Signal Task (SST) selected from Cambridge Neuropsychological Test Automated Battery (CANTAB) was administered to all participants. SST is based on the Logan's theory and it gives an index of Response Inhibition, called Stop Signal Reaction Time (SSRT).

A significant difference in SSRT between HC and the clinical groups was found. No differences in SSRT and number of “Direction Errors” were found between OCD and AN groups. No gender influence on the SST performance was found.OCD group showed slower reaction times to the main task than AN and HC.

Results from neuropsychological assessment have shown a deficit in the Response Inhibition in OCD and AN patients, in line with our hypothesis. Findings supports evidences in literature about OCD patients, but it represents a pioneer result in the contest of AN patients.