Using a novel imaging technology, scientists have shed new light on abnormalities in the brains of anorexia nervosa patients that may contribute to the puzzling symptoms found in people with the eating disorder.
Dr. Walter Kaye, professor of psychiatry and director of the Eating Disorders Program at the University of California, San Diego, says that the research team have gained fresh insights into certain neural circuits of the brain that may help explain why people develop anorexia in the first place, and behaviours such as the relentless pursuit of dieting and weight loss.
"Currently, we don't have very effective means of treating people with anorexia. Consequently, many patients with the disorder remain ill for years or eventually die from the disease, which has the highest death rate of any psychiatric disorder," Nature magazine quoted Kaye as saying.
Study co-author Julie L. Fudge, of the Department of Psychiatry and Neurobiology and Anatomy at the University of Rochester Medical Center, says that imaging studies suggest that individuals with anorexia have an imbalance between circuits in the brain that regulate reward and emotion-the ventral or limbic circuit-and circuits that are associated with consequences and planning ahead-the dorsal or cognitive circuit.
"Brain-imaging studies also show that individuals with anorexia have alterations in those parts of the brain involved with bodily sensations, such as sensing the rewarding aspects of pleasurable foods. Anorexics may literally not recognize when they are hungry," said co-author Martin Paulus, UC San Diego professor of psychiatry, who heads UC San Diego's Laboratory of Biological Dynamics and Theoretical Medicine.
One such brain region is the anterior insula, which is critically important for interoception, or the self-awareness of internal body signals.
In addition to a failure to respond appropriately to signals of hunger, symptoms of anorexia - such as distorted body image and diminished motivation to change - could be related to disturbed interoceptive awareness.
"Anorexia is very complicated, and there needs to be a paradigm shift in understanding its underlying cause. We're just beginning to understand how the brain is working in people with this disorder," said Kaye.
Kaye noted that the temperament and personality traits that may create a vulnerability to develop anorexia might also have a positive aspect.
According to the researcher, such traits include attention to detail, concern about consequences, and a drive to accomplish and succeed.
"It's my clinical experience that many individuals who recover from anorexia do well in life," he said.
A research article on the study has been published in Nature Reviews Neuroscience.