There is still much misconception and misinformation surrounding eating disorders. “You still read more about anorexia in the celebrity section of publications than in health sections,” says Nancy Zucker, PhD, a professor of psychology and neuroscience at Duke University. A lot of the misconception regarding eating disorders centers on the emphasis of it being a culturally guided phenomenon. While culture and environment play a role in shaping the behaviors, evidence is mounting that eating disorders begin in the brain.
Among the class of eating disorders are anorexia, bulimia, and binge-eating—all of which share a dangerously maladaptive approach to food. Further, if left untreated, all can lead to serious medical illnesses. While anorexia and bulimia have distinct features, the disorders appear to share some biological underpinnings; both are highly heritable. Further, people with anorexia and bulimia seem to have relatively similar temperaments. When they’re children, before the onset of the eating disorder, they tend to be anxious, obsessive, perfectionistic, and achievement-oriented.
But eating disorders are more than simply temperament. An important piece to the equation that researchers are discovering is an altered reward system in the brain. Walter Kaye, MD, did research on women with anorexia and healthy women while playing a monetary betting game. In women with anorexia, brain circuits involved in reward processing were less active when they won, but more active when they lost. Further, an important piece of the altered reward system seems to be dopamine—the neurotransmitter that motivates us to reach for a second brownie. Dr. Kaye’s research has also shown that, for people with anorexia, the release of dopamine triggers anxiety rather than pleasure.
Researchers have identified several brain regions involved in the altered reward systems associated with eating disorders. For instance, people with bulimia and anorexia have structural differences in the orbitofrontal cortex. Individuals with anorexia also appear to have more activity in the dorsal striatum—brain area liked to habitual behavior. In addition, the brain area known as the right insula also seems to be altered in people with anorexia. This area helps to process taste sensations as well as awareness of one’s own bodily signals. Thus, the theory is that individuals with anorexia have a hypersensitivity to body signals and sensations that constantly interferes with their ability to focus. Extreme food restriction can then be seen as a coping response to that hypersensitivity.
With all this said, researchers are uncertain as to whether certain brain abnormalities in eating disorders are the cause or consequence. Ultimately, Dr. Kaye says it is most likely a bit of both, but it is not of real importance if we are able to identify and directly intervene on these altered circuits. To date, treatment approaches to eating disorders have not been entirely effective, with very high relapse rates within the community. Thus, researchers are optimistic that neuroscience will help point the way to new therapeutic tools, eating disorder treatment and medication. As researchers begin to discover the brain regions and neural circuits underlying eating disorders, better interventions for the notoriously hard-to-treat illnesses are likely to follow. Eating disorders are ultimately life-threatening illnesses and there is need to discover the contributing factors that can guide new treatment approaches.