Serotonin is a neurotransmitter and hormone found in numerous organs and tissues such as the digestive tract and the brain. In the brain, it plays a critical role in regulating appetite, sleep and mood. In fact, many antidepressant medications elevate a person’s mood by altering levels of serotonin in the brain. With serotonin being so closely involved in mood and appetite, it’s not surprising that researchers have speculated about the role serotonin plays in eating disorders. Are eating disorders and serotonin levels related – and can changes in serotonin levels explain the symptoms that people with eating disorders experience?
Eating Disorders and Serotonin Levels
One of the most common types of eating disorders is anorexia nervosa. People with this disorder, usually women, restrict calories in a relentless pursuit to become thinner. Some people with anorexia nervosa not only restrict calories but also practice cycles of binging and purging in a dangerous attempt to lose weight. This form of anorexia is a subtype of anorexia nervosa called bulimia-type anorexia.
According to a study carried out at the University of Pittsburgh School of Medicine, women who successfully recovered from bulimia-type anorexia have altered serotonin binding (the docking of serotonin molecules to nerve cell receptors) in their brains. They confirmed this finding by using positron emission tomography and a special molecule that binds to serotonin receptors. Specifically, they found that people with bulimia having decreased binding of serotonin to receptors in the brain, and this decrease in serotonin binding persists even after they revert to healthier eating habits. Some studies also suggest that some women with anorexia nervosa have a gene that codes for abnormal serotonin receptors in the brain, which may account for the decreased serotonin binding.
Another argument for an association between eating disorders and serotonin levels is the fact that people with eating disorders often respond to antidepressant medications, which work by altering serotonin levels. Generally, people with bulimic-type of eating disorders where they binge and purge have a better response to antidepressants than people with restrictive types of anorexia nervosa - but antidepressants are used with some success in both groups. , This further supports a connection between eating disorders and serotonin since these medications increase serotonin levels in the brain.
Many People with Eating Disorders Also Suffer From Depression
Studies show that more than eight out of ten people with bulimia also suffer from depression. Depression is another condition associated with alterations in serotonin levels in the brain – more evidence that serotonin and serotonin binding in the brain are involved in eating disorders such as bulimia.
The Bottom Line?
It’s not clear which happens first, the eating disorder or the altered serotonin binding or whether the altered serotonin actually causes the symptoms people with eating disorders experience.
In terms of eating disorders and serotonin, there’s still much more to learn. If altered serotonin binding is responsible for the symptoms of eating disorders such as anorexia or bulimia, medications may play a more important role than psychological counseling, but, in all likelihood, the best approach will still be a combination of medical treatment and talk therapy.
Arch Gen Psychiatry 54:529-534, 1997.
Medical News Today. “Alterations in Brain Serotonin Activity May Be Associated with Anorexia Nervosa”
Psychopharmacology. DOI 10.1007/s00213-007-0896-7. “Serotonin transporter binding after recovery from eating disorders”