Women with BN processed body image stimuli, but not food stimuli, differently than controls.
Reprinted from Eating Disorders Review
January/February Volume 25, Number 1
The neurobiology of persons with bulimia nervosa (BN) is still a mostly unexplored frontier, and much remains to be learned about how the brain processes information about body image. Canadian and British researchers recently reported that among patients with BN the brain responds to body image stimuli but not to food stimuli (BMC Psychiatry 2013; 13:302).
Dr. Frederique Van den Eynde and colleagues at King’s College, London, and McGill University, Toronto, recently used functional magnetic resonance imaging (fMRI) to study 21 people with BN and 23 healthy controls. All participants completed two models: (1) processing visual food stimuli and (2) comparing their own appearance with that of slim women. The participants also rated their food cravings and anxiety levels. The 21 right-handed women seeking treatment for BN were recruited from Maudsley Hospital in the United Kingdom, and the controls were recruited with ads placed at King’s College. All participants completed the Eating Disorders Examination-Questionnaire and the Food Craving Questionnaire—Trait and State, the Social Appearance Anxiety Scale, and the Depression, Anxiety, and Stress Scale.
There were few differences in the way women with BN and the control women processed food stimuli; the only difference was that the bilateral cuneus in the brain was more activated in the women with BN in response to the food stimuli. Women with BN reported higher anxiety levels after exposure to visual food stimuli. In contrast, craving scores were not higher in the BN group in either the food or LLB condition. When they evaluated themselves against images of slim women, BN patients used the insula more and the fusiform gyrus less, compared to healthy controls, suggesting an increased self-focus among women with BN. In women with BN, exposure to food and body image stimuli increased self-reported levels of anxiety, but not of craving. According to the authors, it seems that food provokes more anxiety rather than craving among people with BN compared to controls. It is possible that visual presentation of food stimuli is less significant than other forms of exposure, such as real food or virtual reality.
The authors note that while little is known about the role of the cuneus during eating, there is indirect evidence that this structure in the brain may be involved in food-associated reward. Successful treatment may have an effect on the cuneus because recovered BN patients reportedly show less activation in that area when given a taste of glucose. Their study did not replicate previous findings of reduced dorsolateral prefrontal cortex activity.
Thus, processing visual food stimuli and comparing oneself to other slim women elicits more anxiety but not more food cravings in women with BN compared to normal controls. Women with and without BN use the insula more (that is, they reflect more upon themselves) and use the fusiform gyrus less (they look less at another person’s actual shape). The authors report that this supports the idea that psychotherapy of BN should not solely focus on food and eating-related issues, but instead should target body image.
The results of the study had several clinical implications. One is that the development of future directed interventions, such as trancranial or deep brain stimulation, using low-frequency, inhibitory transcranial or deep brain stimulation of the insula, may reduce body image concerns. Another clinical implication is that psychotherapy for BN should not solely target food- and eating-related issues, but instead should focus on body image.