A new study has found that the brain's response to taste stimuli is linked to high anxiety and a drive for thinness that could play a role in driving anorexia nervosa.

The researchers, led by Dr. Guido Frank, MD, associate professor of psychiatry and neuroscience at the University Of Colorado School Of Medicine, monitored a large group of patients with anorexia nervosa as they tasted sugar during brain imaging. Frank found that as these patients restricted their diet, a brain reward circuit associated with the neurotransmitter dopamine becomes more active but also triggers anxiety. This makes food avoidance worse and perpetuates the often deadly disease.

The researchers found their brain response was higher than those in the control group, representing a biological marker for the illness. At the same time, this brain response was related to high anxiety and less weight gain for those being treated for anorexia nervosa. "When you lose weight your brain reward response goes up," said Frank. "But instead of driving eating, we believe it elevates anxiety in anorexia nervosa, which makes them want to restrict more. This becomes then a vicious cycle."

Frank discovered that the higher the brain response, the lower the weight gain during treatment. According to Frank, anorexia nervosa behavior could alter the brain circuits and impact its taste-reward processing mechanisms. Those who are already worried about shape and weight become even more concerned.

The study noted that while most people like sweet tasting things, those with eating disorders associate the taste with weight gain and try to avoid it. Frank found that the brain activation in the anorexia group was inversely connected with any pleasant experience of eating sugar. The full findings appeared in the journal- JAMA Psychiatry.