Psiquiatria

Article

Aberrant Brain Activation During a Response Inhibition Task in Adolescent Eating Disorder Subtypes

James Lock, M.D., Ph.D. Amy Garrett, Ph.D. Judy Beenhakker, M.S. Allan L. Reiss, M.D.

Objective: Behavioral and personality characteristics associated with excessive inhibition and disinhibition are observed in patients with eating disorders, but neural correlates of inhibitorycontrol have not been examined in adolescents with these disorders. Method: Thirteen female adolescents with binge eating and purging behaviors (i.e., bulimia nervosa or anorexia nervosa, binge eating/purging type);14 with anorexia nervosa, restricting type; and 13 healthy comparison subjects performed a rapid, jittered event-related go/no-go task. Functional magnetic resonance images were collectedusing a 3 Tesla GE scanner and a spiral pulse sequence. A whole-brain three-group analysis of variance in SPM5 was used to identify significant activation associated with the main effect of group for the comparison of correct no-go versus go trials. The mean activation in these clusters was extracted for further comparisons in SPSS.

Results: The binge eating/purging group showed significantlygreater activation than the healthy comparison group in the bilateral precentral gyri, anterior cingulate cortex, and middle and superior temporal gyri as well as greater activation relative to both comparison and restricting type anorexia subjects in the hypothalamus and right dorsolateral prefrontal cortex. Within-group analysis found that only the restricting type anorexia group showed a positivecorrelation between the percent correct on no-go trials and activation in posterior visual and inferior parietal cortex regions. Conclusions: The present study provides preliminary evidence that during adolescence, eating disorder subtypes may be distinguishable in terms of neural correlates of inhibitory control. This distinction is consistent with differences in behavioral impulsivity in thesepatient groups. (Am J Psychiatry 2011; 168:55–64)

ehavior and personality characteristics differ among patients with eating disorders, depending on subtype. Patients with binge eating or purging behaviors, such as anorexia nervosa, binge eating/purging type, and/or bulimia nervosa, often display impulsive and disinhibited personality characteristics. In contrast, those with anorexia nervosa,restricting type (1–3), often show a restrictive and overly controlled behavioral style. Disinhibition and impulsivity related to eating behaviors are hallmarks of bulimia nervosa (4, 5). In recognition of this core feature of the disorder, the DSM-IV diagnostic description of bulimia nervosa incorporates the requirement that binge eating episodes include this disinhibited (out of control)characteristic (6). Impulsivity may extend into other areas of life in addition to binge eating or purging (2). For example, individuals with bulimia nervosa often report alcohol and drug abuse, self-harm, sexual disinhibition, and shoplifting (5). Some data suggest that the basis of cognitive and behavioral disinhibition in bulimia nervosa may be related to serotonin dysregulation (7), whileneuropsychological studies have found evidence of disinhibition at a neurocognitive level in affected
Am J Psychiatry 168:1, January 2011

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individuals. For example, relative to healthy comparison subjects, individuals with bulimia nervosa who used laxatives were observed to make more errors of commission on a go/no-go task and endorse higher ratings for impulsive behaviors on a self-report assessment(4). Similarly, cognitive research in inhibitory processing using a motor stop-signal paradigm and a motor Stroop task found that patients with restricting type anorexia displayed superior response inhibition overall, with fewer impulsive errors, than patients with the binge eating/purging type (8). Anorexia nervosa patients with binge eating/purging behaviors also made more response errors on a...