Functional MRI (fMRI) revealed that the self-regulatory processes are impaired in women with bulimia nervosa, likely because of their failure to engage frontostriatal circuits appropriately, according to a report in the January issue of Archives of General Psychiatry.
Bulimia nervosa (BN) often begins in the adolescent or young adult years, according to background information in the article. “Primarily affecting girls and women, it is characterized by recurrent episodes of binge eating followed by self-induced vomiting or another compensatory behavior to avoid weight gain,” the authors wrote. “These episodes of binge eating are associated with a severe sense of loss of control.”
Rachel Marsh, PhD, and colleagues at Columbia University and the New York State Psychiatric Institute in New York City, compared the performance on the task of 20 women with BN with that of 20 healthy women, who served as controls. Participants performed the task while undergoing fMRI.
Patients with BN responded more impulsively and made more errors on the task than did healthy controls; patients with the most severe symptoms made the most errors. During correct responding on incongruent trials, patients failed to activate frontostriatal circuits to the same degree as healthy controls in the left inferolateral prefrontal cortex (Brodmann area [BA] 45), bilateral inferior frontal gyrus (BA 44), lenticular and caudate nuclei, and anterior cingulate cortex (BA 24/32). Patients activated the dorsal anterior cingulate cortex (BA 32) more when making errors than when responding correctly.
In contrast, healthy participants activated the anterior cingulate cortex more during correct than incorrect responses, and they activated the striatum more when responding incorrectly, likely reflecting an automatic response tendency that, in the absence of concomitant anterior cingulate cortex activity, produced incorrect responses.
“These group differences in performance and patterns of brain activity suggest that individuals with bulimia nervosa do not activate frontostriatal circuits appropriately, perhaps contributing to impulsive responses to conflict stimuli that normally require both frontostriatal activation and the exercise of self-regulatory control to generate a correct response,” the authors concluded. “We speculate that this inability to engage frontostriatal systems also contributes to their inability to regulate binge-type eating and other impulsive behaviors.”
To expand on this hypothesis, they noted that future studies should also include impulsive individuals who have healthy weights and eating behaviors, adolescents close to the time that BN develops and patients with varying severity of symptoms.
The study was supported in part by grants from the National Institute of Mental Health, by a grant from the National Alliance for Research on Schizophrenia and Depression and by funding from the Sackler Institute for Developmental Psychobiology, Columbia University.