Women with bulimia nervosa (BN), when compared with healthy women, showed different patterns of brain activity while doing a task that required self-regulation. This abnormality may underlie binge eating and other impulsive behaviors that occur with the eating disorder, according to an article published in the January 2009 issue of the Archives of General Psychiatry.
In the first study of its kind, Rachel Marsh, Ph.D., Columbia University, and colleagues assessed self-regulatory brain processes in women with BN without using disorder-specific cues, such as pictures of food.
In this study, 20 women with BN and 20 healthy controls viewed a series of arrows presented on a computer screen. Their task was to identify the direction in which the arrows were pointing while the researchers observed their brain activity using functional magnetic resonance imaging (fMRI).
People generally complete such tasks easily when the direction of the arrow matches the side of the screen it is on—an arrow on the left side pointing to the left—but respond more slowly and with more errors when the two do not match. In such cases, healthy adults activate self-regulatory processes in the brain to prevent automatic responses and to focus greater attention on resolving the conflicting information.
Results of the Study
Women with BN tended to be more impulsive during the task, responding faster and making more mistakes when presented with conflicting information, compared with healthy controls.
Patterns in brain activity also differed between the two groups. Even when they answered correctly to conflicting information, women with BN generally did not show as much activity in brain areas involved in self-regulation as healthy controls did. Women with the most severe cases of the disorder showed the least amount of self-regulatory brain activity and made the most errors on the task.
Altered patterns of brain activity may underlie impaired self-regulation and impulse control problems in women with BN. These findings increase the understanding of causes of binge eating and other impulsive behaviors associated with BN and may help researchers to develop better targeted treatments.
The researchers are currently conducting further studies on brain functioning in teens with BN, which would offer a closer look at the beginnings of the illness. They also recommend studying people in remission from an eating disorder. Comparison studies with impulsive people who have healthy weight and eating habits could also provide more information about which patterns of brain activity are most directly related to eating disorders.
fMRI data showing self-regulatory brain activity in healthy controls (left) and women with BN (right). Red areas show increases in activity while answering correctly when given conflicting information. Blue areas show increases in activity while answering correctly when given matching information. In both cases, women with BN showed less activity than healthy controls.
These differences in brain activity patterns may account for problems with impulse control and similar behaviors related to BN.