Although many people find it difficult to diet and lose weight, people suffering from anorexia nervosa can actually diet themselves to death, and many die from starvation and its effects on the body. A new study gives insight as to why these symptoms can occur in people with anorexia.
A major symptom of anorexia is the refusal to eat, which results in extreme weight loss. Most healthy people find eating to be a pleasurable, rewarding experience. However, people with anorexia often say that eating makes them feel anxious, and refusing food makes them feel better.
Research over the last ten years has provided insight into the brain mechanisms that are associated with the rewarding aspects of eating. One chemical that is responsible is dopamine, a neurotransmitter that is released in the brain after pleasurable activities, such as using drugs, having sex, and eating tasty food.
The current study, led by Walter Kaye, MD, professor of psychiatry and director of the Eating Disorder Treatment and Research Program at the University of California, San Diego School of Medicine, used positron emission tomography (PET) to examine dopamine activity in the brain after administering a dose of amphetamine to participants, some of which were healthy and some of which had anorexia nervosa.
In healthy women, the amphetamine-induced release of dopamine was related to feelings of extreme pleasure in the reward system of the brain; however, in those with anorexia, amphetamine made them feel anxious, and the part of the brain that was activated was a part that worries about consequences, rather than the reward system.
Dr. Kaye said this is the first study to show a biological reason why people with anorexia have this mysterious reaction to food. He said that when people with anorexia eat, the release of dopamine makes them anxious, rather than rewarded. This suggests why it can be so difficult for people with anorexia to gain weight and eat.
An important part of this study is that it examined people who had recovered from anorexia for at least a year, suggesting that the anxiety produced by eating may be due to pre-existing traits, rather than a response to being at an extremely low weight.
This finding could help scientists develop treatments that target dopamine receptors to help lessen the anxiety that comes with eating for people with anorexia. In addition, treating the anxiety could help treat the eating disorder.
Source: Science Daily, Does Eating Give You Pleasure, or Make You Anxious?, May 19, 2011