New research in an article on the brain differences in bulimics appears in the January issue of the Archives of General Psychiatry. The study consisted of 40 participants (20 with bulimia who had a median duration of illness of nine years and 20 healthy controls). While undergoing functional magnetic resonance imaging, participants were shown pictures with arrows pointing left and right and were asked to identify which direction the arrows were pointing, regardless of where the arrows were on the screen. This is also known as the Simon Spatial Incompatibility Task.
The results showed the bulimics were faster but less accurate on more difficult trials which indicated impulsivity and less self-regulatory control. During correct trials, those with bulimia had less activity in their frontostriatal region than healthy controls. In incorrect responses, bulimics activated the dorsal anterior cingulate cortex more often. This contrasted from the healthy controls who activated the anterior cingulate cortex while responding correctly more and the striatum during incorrect responses.
The importance of researching the frontostriatal region of the brain is because it regulates both serotonin and dopamine. Research has often implicated serotonin and bulimia, but dopamine hasn't been studied as frequently.
The other interesting question this brings up is what Daniel le Grange, author of the new book Help Your Teen Beat an Eating Disorder asks, "Does the abnormality occur because someone has bulimia nervosa, or does it contribute to developing it?"
This reminds me of the chicken and egg syndrome which invariably can be different for everyone. Depression and eating disorders is often used as an example. Some will say it was the depression that set off their eating disorder, while others say it was vice versa. I don't know if there is one right answer. But what I do think is that the perceptibility to an eating disorder already exists, whether through genetics or neurocircuitry, and perhaps through engaging in more disorderedness, the brain further changes. I could be completely wrong though too and maybe it's just rewiring from the beginning. More research is already underway looking at adolescent brains whose onset of illness is of less duration than those in this particular study.