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Bulimia Nervosa: A Failure of the Food Intake Regulatory System?

Hollie Black

April 26, 2010

 

Eating disorders like anorexia nervosa, bulimia nervosa, and binge eating are some of the least understood mental illnesses of today. Several studies have been conducted to try to find the true cause for said disorders, but there are many inconclusive results that give several possibilities that could have contributed to the eating disorder. Recently, studies that have been conducted to test the mechanisms within the brains of people with eating disorders (particularly bulimia) have shown a dysregulation of neurotransmitters. The most common problem has been the failure of serotonin to be retaken up, which some studies have concluded could be the cause for the eating disorder.

Bulimia Nervosa

            Bulimia Nervosa (BN) is a type of eating disorder that is characterized by the DSM-5 as

A. Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following:

(1) Eating, in a discrete period of time (e.g., within any 2-hour period), an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances

(2) A sense of lack of control over eating during the episode (e.g., a feeling that one cannot stop eating or control what or how much one is eating).

B. Recurrent inappropriate compensatory behavior in order to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics, or other medications, fasting; or excessive exercise.

C. The binge eating and inappropriate compensatory behaviors both occur, on average, at least once a week for 3 months.

D. Self-evaluation is unduly influenced by body shape and weight.

E. The disturbance does not occur exclusively during episodes of anorexia nervosa.” (American Psychiatric Association, 2010)

Over time, bulimia can cause several health problems including tooth decay, acid-reflux, dehydration, heart palpitations and even death. There are several theories on what are the causes of bulimia. They can develop from biological, personality, emotional health, and environmental problems (Mayo Foundation for Medical Education and Research , 2010). Biologically, a person can be susceptible to developing bulimia if serotonin levels, which control eating behavior, emotions, and judgment, are too high or too low.

Serotonin

Serotonin (5-HT) is a multifunctional neurotransmitter that can be found throughout the body. Neurotransmitters act as nerve communicators that work in neural pathways of the peripheral and central nervous system. In the brain, serotonin acts as a regulator for mood and appetite (Wikipedia Contributers, 2010).

                                                             

Lowered serotonin levels can lead to anxiety and depression and increased appetite. People with bulimia nervosa typically have imbalanced serotonin levels, which explains their extreme appetite, and increased anxiety and depression, which leads to the feel that one must purge to relieve some of the residual anxiety associated with the food ingested and daily life.

Literature Review

Several studies have been conducted trying to find a strong connection between serotonin dysregulation and the prevalence of the development of eating disorders, particularly bulimia nervosa. A literature analysis by Walter Kaye, M.D. a professor of Psychology at the University of Pittsburgh Medical Center looked into the effects of the dysregulations of neuronal signals have on the development of eating disorders. The analysis concluded that based on research, people with certain traits or genes that promote 5-HT dysregulation could develop anxiety and depression. During puberty these symptoms can be exacerbated due to the fluctuations in hormones and can lead to extreme changes in mood and appetite due to increased serotonin dysregulation making these people highly susceptible to developing bulimia or another eating disorders (Kaye, 2007). A cross-clinical study performed by several psychiatric clinicians at a number of university hospitals around the world was executed to further understand the biological mechanisms BN and other eating disorders. Ninety-two women with bulimic tendencies were tested for expressing a gene that was associated for a certain type of serotonin that causes dysregulation of appetite and mood common to people with eating disorders.  The study found those individuals with the mutation in the 5-HT gene coupled with physical or sexual abuse in early childhood showed the strongest symptoms of BN along with a number of other anxiety disorders(Howard Steiger, 2007). This study did not however did not have any conclusive statements on those with bulimia, the serotonin mutated gene, but no physical or sexual abuse in their past. They did however conclude that those individuals who have both the gene and a history of abuse should be treated more rigorously with both therapy and pharmacological support (Howard Steiger, 2007). In a comparison between current and recovering bulimics’ serotonin receptor activity, a group of universities found that there was a more than 100% increase in serotonin receptor activity in the current bulimics as compared with those that were recovering bulimics (Walter H. Kaye, 2008).

 (Walter H. Kaye, 2008)

Found in both groups, was an abnormal binding of another 5-HT receptor. This imbalance in receptor activity may contribute to the symptoms that are associated with BN (Kaye, 2007).

Findings and Suggestions

Based on current studies, it is clear that there is a dysregulation of the 5-HT receptors that predates the development of BN. This imbalance is responsible for the co morbid anxiety and perfectionist behavior in childhood that is associated with bulimia. In the future bulimia and anorexia could be combated before they have the ability to develop. If bulimia runs a family, tests for serotonin imbalances could be performed on the children to insure that they are not at a higher risk of developing an eating disorders and other anxiety disorders. If these levels can be normalized early the risk of developing said disorders can be reduced drastically.

 

 

 

 

 

 

 

Bibliography

American Psychiatric Association. (2010). DSM- 5 Development: Bulimia. Retrieved April 25, 2010 from American Psychiatric Association: http://www.dsm5.org/ProposedRevisions/Pages/proposedrevision.aspx?rid=25

Howard Steiger, P. J. (2007). The 5HTTLPR polymorphism, prior maltreatment and dramatic–erratic personality manifestations in women with bulimic syndromes. Journal of Psychiatry Neuroscience , 32 (5), 354-362.

Kaye, W. (2007). Neurobiology of anorexia and bulimia nervosa. Physiology and Behavior , 94 (1), 121-135.

Kuchinskas, S. (2010, April 22). Eating Disorders: Not Just a Teen Problem. Retrieved April 25, 2010 from WebMD: http://www.webmd.com/mental-health/features/eating-disorders-not-just-a-teen-problem

Mayo Foundation for Medical Education and Research . (2010). Bulimia nervosa. Retrieved April 25, 2010 from MayoClinic.com: http://www.mayoclinic.com/health/bulimia/DS00607/DSECTION=causes

Walter H. Kaye, U. B. (2008). Altered 5-HT1A and 5-HT2A receptor interactions in anorexia and bulimia nervosa. NeuroImage , 41 (2), 155.

Wikipedia Contributers. (2010, April 22). Serotonin. Retrieved April 25, 2010 from Wikipedia, The Free Encyclopedia: http://en.wikipedia.org/wiki/Serotonin

 

 

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