Biological Factors of Bulimia Nervosa

Bulimia Nervosa is characterized by uncontrollable binge eating and making efforts to prevent weight gain by different self-induced methods such as vomiting or eating laxatives. It was actually established by a psychiatrist G.F.M. Russell in 1979 and then later on was adopted by DSM in 1987. From its Greek origin, Bulimia means buos (which means “ox”) and limos (which means “hunger”); meaning such a hunger that the person could eat an ox. According to DSM – V, the diagnostic criteria for Bulimia Nervosa is that the binge-eating has to occur once a week in a 3-month period, unlike in DSM- IV where it was twice a week. (Association, 2013)

The difference between Bulimic-type Anorexia Nervosa and Bulimia Nervosa is that, in patients with Anorexia Nervosa, they are in the range of severely low weight, where as in Bulimia Nervosa, the person is in normal to overweight range. 

The course of Bulimia Nervosa is very different from Anorexia Nervosa. It starts with the restrictive dieting due to the desire to reach a certain body weight and image. The person only eats low-calorie food items, but sometime after this stage, the person has a desire to eat “forbidden foods” or the food that will make them gain weight. They start binging these food items, such as chocolate, burger, cake and noodles. Then they realize that they are gaining weight so to prevent that they make efforts to self-control behaviors like self-induced vomiting or excessive exercise. This action comes from the fear of gaining weight. (Association, 2013)

The epidemiology of all eating disorders is still in active research but researchers have gathered few knowledge over Anorexia Nervosa and Bulimia Nervosa. This article is focusing on the biological factors of Bulimia Nervosa, which has many aspects to link this eating disorder to our genes and physiological functioning. 

 

  • Genetic Factors: Attention is given to research in the area of genetic links of eating disorders and it has been found that eating disorders run in the families and relatives. For the biological relatives of Bulimia Nervosa, there is a three times fold (3.7 times) in the risk factor of Bulimia Nervosa for the relatives, which is less than it is for Anorexia Nervosa (11.4 times). 

 

Also to be noted that there is a susceptibility in relatives of people suffering from BN that they are likely to develop other issues like alcohol and drug use and dependence. (Bulik, 2016)

The studies show that the genetic likelihood of developing an eating disorder is as likely as developing schizophrenia or a personality disorder. It has been reported that the eating disorders are most probably heritable disorders. (Dash, 2019)

 

 

  • Brain Abnormalities: The brain has an area called hypothalamus which has an important role in regulation of hunger and eating. There are two different parts of it which triggers hunger and eating respectively. One is ventromedial hypothalamus (VMH) which triggers inhibition of food intake and the other, lateral hypothalamus triggers hunger and then voracious eating.  It is seen that there are lesions found in both the areas in an animal study, which leads to dysregulation of eating and hunger. VMH triggers eating and lateral hypothalamus inhibits eating. Because of these lesions, the eating disorders prevail in many adolescents and young adults. (Frank, 2016)

 

 

 

  • Serotonin: Serotonin is a neurotransmitter that is involved in mood disorders, impulsivity and it also modulates the regulation of appetite and food intake. Serotonin is made from the amino acid called tryptophan. It is only found in food items. Hence the level of serotonin defines the regulation of food items. But the level of HIAA (tryptophan gene) is very low in anorexia and normal in bulimia nervosa. It is reported that the recovery in BN patients gave an increase to the level of HIAA and serotonin. The high levels of serotonin is found to be beneficial to the patients suffering from eating disorders. It is suggested to maintain a healthy diet, so that the serotonin stays balanced.  (Sjögren, 2019)

 

Eating disorders like Anorexia and Bulimia Nervosa requires extensive intervention plan which can reconstruct a person’s mindset and their cognitive processes, with the proper healthy diet and nutrients balanced according to each patient.

 

References:

  1. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 5th edition. Arlington, VA., American Psychiatric Association, 2013.
  2. Bulik, C. M., Kleiman, S. C., & Yilmaz, Z. (2016). Genetic epidemiology of eating disorders. Current opinion in psychiatry, 29(6), 383. https://dx.doi.org/10.1097%2FYCO.0000000000000275 
  3. Dash, S. (2019). The impact of genetic and cultural factors on anorexia and bulimia. Life Research2(2), 71-79. https://dx.doi.org/10.12032/life2019-0425-004 
  4. Frank, G. K. W., Shott, M. E., Riederer, J., & Pryor, T. L. (2016). Altered structural and effective connectivity in anorexia and bulimia nervosa in circuits that regulate energy and reward homeostasis. Translational psychiatry6(11), e932-e932. https://doi.org/10.1038/tp.2016.199 
  5. Sjögren, M., Nielsen, A. S. M., Hasselbalch, K. C., Wøllo, M., & Hansen, J. S. (2019). A systematic review of blood-based serotonergic biomarkers in Bulimia Nervosa. Psychiatry research279, 155-171. https://doi.org/10.1016/j.psychres.2018.12.167 
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