Dysfunctions in the part of the brain responsible for processing visual information have been linked to both anorexia nervosa and body dysmorphic disorder (BDD), a new study finds. The two conditions appear to stem from a mismatch between how things look in totality, or “globally,” and how details appear on their own.
Popular notions of anorexia nervosa may assume the disorder stems from BDD, as people who dislike how they look take drastic measures to lose weight or avoid further weight gain. But the two cases don’t necessarily accompany one another. Overweight people, for instance, can still suffer from BDD if they focus intensely on one aspect of their physical appearance, rather than their overall health. Understanding how the brain analyzes this kind of unique visual information may offer new avenues for treatment.
“Previously, we knew where these visual processing abnormalities existed in the brain in body dysmorphic disorder, but did not know when they were taking place,” said Dr. Jamie Feusner, senior author of the study and professor of psychiatry at UCLA, in a statement. That timing is important, Feusner added, because it tells researchers whether errors are occurring in the visual cortex or in higher-level brain function.
In their study, Feusner and his colleagues collected data on when people’s brains began receiving information about a given stimulus. Unmedicated subjects with either anorexia nervosa, BDD, or neither, looked at images of houses and people’s faces — so chosen for their differences in immediate impressions. Meanwhile, an fMRI scanner recorded brain activity via the blood flow to certain areas. The team found that people with either disorder had more abnormal behavior in the part of the visual cortex that sees objects as a whole. This was coupled with increased activity in the regions that are responsible for seeing fine detail. What’s more, the greater activity Feusner and his team saw, the more likely the subject was to rate a face as unattractive.
“This understanding,” said the study’s first author, Wei Li, “has the potential to lead to new strategies that can improve the way we treat these disorders.”
The latest statistics on anorexia nervosa suggest the disorder has yet to receive the widespread attention it deserves given its prevalence. Upward of 30 million people are thought to suffer from some type of eating disorder, yet a small minority will ever receive treatment, either out of embarrassment, fear, or a lack of awareness about the signs. Unlike anorexia, which is classified simply as a lack of appetite and tends to arise as a symptom from another condition or disease, like cancer, anorexia nervosa has more complex psychiatric roots. One 1995 study found eating disorders carry the highest mortality rate of any mental illness.
Now that the team knows the timing of visual processing related to anorexia nervosa and BDD, they hope to conduct follow-up tests that shift people’s perceptions away from the details, and more toward the bigger picture. BDD, especially, causes people to isolate one part of their body — love handles, loose skin, a crooked nose — and inflate its importance to reflect their overall attractiveness and self-worth. “Among the questions to be answered in future research,” Li said, “is whether this dysfunction improves as a result of treatment, and if not, what perceptual retraining techniques could help sufferers of these illnesses.”
Source: Li W, Laia T, Bohona C, et al. Anorexia nervosa and body dysmorphic disorder are associated with abnormalities in processing visual information. Psychological Medicine. 2015.