Women with bulimia nervosa appear to respond more impulsively during psychological testing than those without eating disorders, and brain scans show differences in areas responsible for regulating behavior, according to a report in the January issue of Archives of General Psychiatry.
Bulimia nervosa 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 write. "These episodes of binge eating are associated with a severe sense of loss of control."
Certain pathways between nerve cells known as frontostriatal circuits help individuals control their own voluntary behaviors, the authors note. These functions are tested during the performance of the Simon Spatial Incompatibility task, in which participants must indicate the direction an arrow is pointing regardless of where it appears on a screen. The task is easier when the arrow direction matches the side of the screen, but more difficult when, for instance, an arrow that points leftward appears on the right side of the screen. Ignoring the side of the screen to focus on the arrow direction requires regulating behavior by fighting the tendency to respond automatically and resolving conflicting messages.
Rachel Marsh, Ph.D., and colleagues at Columbia University and the New York State Psychiatric Institute, New York, compared the performance on the task of 20 women with bulimia nervosa with that of 20 healthy women who served as controls. Participants performed the task while undergoing functional magnetic resonance imaging (fMRI).