The study, published in January's edition of the Archives of General Psychiatry, included 20 women with bulimia and 20 women without bulimia. The women's ages and BMI were similar in both groups.
Each woman had her brain scanned using functional magnetic resonance imaging (fMRI) while she took a brain function test. In the test, arrows pointing to the left or right popped up on the right or left side of a screen, and the women had to press a button to indicate the arrow's direction.
That task is easier when the arrow's direction matches its position on the screen (such as a left-pointing arrow on the left side of the screen) than when there's a conflict (for instance, the left-pointing arrow on the right side of the screen).
In the test, the arrows come and go quickly; participants' scores are based on accuracy and speed.
The women with bulimia nervosa did worse on the test, particularly because they were more impulsive and inaccurate when the arrow's direction didn't match its screen location. And the women with the most severe bulimia symptoms had the least success on the test.
The brain scans showed that the bulimic women had less activity in brain areas involved in self-regulation.
The reasons for the different brain activity patterns aren't clear. The researchers, who included Rachel Marsh, PhD, of Columbia University and the New York State Psychiatric Institute, speculate that problems with the brain chemicals serotonin and dopamine may be involved.
Because the women who took part in the study were in their mid-20s on average, it's not clear if the findings apply to younger bulimia patients or men with bulimia.