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STUDY OVERVIEW Overview The cause of eating disorders is thought to be
complex and influenced by psychological, cultural, and biological
factors. However, the exact nature of these interactive processes
remains unclear. The search for biological factors which may
contribute to vulnerability for developing anorexia and bulimia
nervosa is the focus of our research. Better understanding of the
biological contribution to eating disorders might inform and improve
both prevention and treatment efforts. The nerve cells in the brain use neurotransmitters, which are chemicals, to send messages to each other. Studies of these chemicals may help us learn more about disturbances of appetite, weight, and behavior. Many people who have eating disorders have problems with depression, anxiety, and obsessions, in addition to alterations in eating patterns. One way of looking at this association between depression, anxiety, and abnormal eating patterns is to see if these problems represent some change in the activity of certain chemicals in the brain. Chemicals that may be of particular importance are the neurotransmitters serotonin and dopamine. These neurotransmitters have been linked to the control of hunger as well as depression, anxiety and obsessions, physical activity, and reward. Moreover, other studies have suggested that serotonin and dopamine may play a role in anorexia and bulimia nervosa. Positron Emission Tomography (PET) Studies Investigating Serotonin and Dopamine Function in Anorexia Nervosa and Bulimia Nervosa One problem in trying to determine if alterations
in brain mechanisms are related to eating disorders is that studying
chemicals in peoples’ brains has been very difficult until
recently. Now, the technology of Positron Emission Tomography (PET)
allows us to more clearly assess the activity of serotonin and
dopamine in the brain. PET scanning produces images that show
changes in brain chemistry which may be associated with eating
disorders. More specifically, we are looking at the receptors
for the serotonin system. Serotonin and dopamine molecules are
secreted by neurons in the brain and work by stimulating specific
receptors on other neurons. In this way, the neurons in the brain
can communicate with each other. The receptors that we are
investigating are called serotonin1A, serotonin2A, and dopamineD2.
In addition, we are investigating the serotonin transporter, which
is a component of the serotonin system that increases the amount of
serotonin in neurons. Our research studies use PET images to examine if there are differences in serotonin and dopamine pathways in women who have suffered from eating disorders and those who have never had an eating disorder. By studying these differences, we hope to better understand the neurobiology of anorexia nervosa and bulimia nervosa. Functional Magnetic Resonance Imaging (fMRI) of Anorexia or Bulimia Nervosa Another new technology for understanding the brain is called functional magnetic resonace imaging (fMRI). fMRI is different from PET. While PET imaging can potentially show overall differences in neurotransmitter function, fMRI imaging permits investigations of how brain regions respond to various stimuli, e.g., food. In fact, certain parts of the brain are very important in modulating hunger and fullness. fMRI uses powerful magnetic fields, which magnetize chemicals in the brain. This allows a scanner and computer to take a very detailed picture of the structure and activity of the brain. By utilizing this technology, scientists are able to see changes in blood flow and oxygen use of the brain during eating.
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