Dysfunction of response inhibition in eating disorders.

INTRODUCTION Response inhibition in eating disorders (ED) has been studied using methods such as Go/No-go tasks and cognitive conflict tasks, but the results have been inconsistent with regard to the presence or absence of impaired response inhibition in ED. This may be due to variation across the studies in the characteristics of the tasks and in the degree of underweight of ED participants. METHOD We investigated the presence or absence of impaired response inhibition in an ED patient group, including many severe cases (body mass index <15 kg/m(2)), by comparing the interference effect of ED patients and healthy participants with an arrow-space interference task as the cognitive conflict task. RESULTS There was a significant interference effect on response time in healthy participants and ED patients, with no significant intergroup difference in response times. However, the interference effect on error rate was significantly greater in ED patients than healthy participants. There was no significant difference in this trend across different ED subtypes (restricting type anorexia nervosa, binge-eating/purging type anorexia nervosa, and eating disorder not otherwise specified). CONCLUSIONS Attentional control such as focused attention and sustained attention are preserved in ED patients, but there appears to be dysfunction of response inhibition. This might be the basis of poor impulse control in the eating behavior of ED patients.