For most people find it hard to diet, especially when last several months. But not so with people with anorexia nervosa, to whom the decision to stop eating may cause death. So far, the strong refusal to eat had no clear explanation. A new study at the University of California provides new clues for understanding why people have anxiety disorder after eating, instead of the normal feeling of pleasure or satisfaction.
“This is the first study to show that there is a biological cause for this paradoxical response to food,” says Walter Kaye, a psychiatry professor and director of Research and Treatment of eating disorders at the university. During the last decade, failed to understand in more detail how food triggers rewarding sensations. These brain mechanisms involving dopamine, a chemical that is released in the brain when animals or people eat tasty food.
Kaye and his group of researchers selected women with anorexia nervosa and without eating disorders and they generated ‘stimuli of dopamine “using a dose of the drug amphetamine, which also releases the chemical in the brain. Then, using a technique called positron emission tomography (PET for short in English) obtained images of brain function in response to dopamine.
The results of this work, published in the International Journal of Eating Disorders, suggest that in healthy women, the release of dopamine produced sensations of pleasure in the brain region known as “reward center.” However, in women with anorexia nervosa, released dopamine produced feelings of anxiety. In these cases, the scientists could see that it activated a different brain region, which is related to the “concern about the consequences.”
For Kaye, the study could explain why sufferers of anorexia nervosa have difficulty eating and weight gain. “It is possible that dopamine generated by the food they generate intense feelings of anxiety and unpleasant,” said the expert.
Because the study was conducted in patients who were recovering anorexic from at least one year, the researchers suggest that the anxiety experienced is due to existing features in the patients and extremely low birth weight caused by the disease.
At the moment it is premature to anticipate the impact of these results in therapies for anorexia. There is still no proven treatments to reduce the core symptoms of the disease, such as anxiety induced by food. For experts, it remains critical to ensure that patients eat and gain weight to treat this disease effectively.