Abnormal Brain Regulation Linked to Bulimia

The mystery of how and why bulimia nervosa occurs has yet to be unraveled. Although it can develop at any age, it most often occurs during the late teen years and affects roughly 8 out of 100 women at some time during their lives, making it far more prominent among women than men.

There are strong suspicions among experts that bulimia nervosa may have a genetic association and prior research has suggested that lows levels of serotonin may be involved. The condition is often accompanied by other mental health problems such as obsessive-compulsive disorder, depression, and anxiety.

Bulimia nervosa is characterized by binge eating followed by purging episodes, employing such methods such as vomiting and ingesting laxatives. Researchers are only in the early stages of beginning to understand the cause and effects of eating disorders. However, new research has revealed that women suffering from bulimia nervosa may be predominantly impulsive due to patterns of brain activity. In a study of 40 women, in which half of the women were experiencing the effects of the condition while the other half were not, the bulimic women were shown to have less activity in brain areas involving self-regulation compared to the non-bulimic women. The study was published in January's edition of the Archives of General Psychiatry.

During the study, each subject’s brain was scanned with the use of functional magnet resonance imaging (fMRI) while participating in a test of brain function. The test consisted of arrows randomly appearing on the left or right side of a screen that also pointed either left or right. The women were to press a button indicating the direction of each arrow. These arrows came and went very quickly and participant scores were based on speed as well as accuracy.

When the arrow direction was in line with its position on the screen, such as a right-pointing arrow on the right side of the screen, the responses came easier than when there was a variance such as a right-pointing arrow appearing on the left side of the screen. Because the women with bulimia nervosa were more impulsive and inaccurate when the arrow's direction was not in line with its location on the screen, they were particularly less successful during the test than the non-bulimic women. In fact, the participants suffering from the most severe bulimia symptoms had the worst test results.

According to the researchers, although the reasons for the variation in brain activity patterns remain unclear, the differences may be an indication that levels of serotonin or dopamine are involved. However, because the average age of the study subjects was 26, it is not known if the findings are applicable to younger bulimic patients or men who suffer from the condition.

Study author Rachel Marsh, an assistant professor of clinical psychology in the division of child and adolescent psychiatry at Columbia University in New York City said, “These findings argue for looking more directly into dopamine systems in eating disorders.” However, further research will be needed to determine if the abnormality occurs as a result of having bulimia nervosa or if having the abnormality contributes to the development of the condition.