Editing Bulimia nervosa (section)

==Causes==

===Biological===

As with [[anorexia nervosa]], there is evidence of genetic predispositions contributing to the onset of this eating disorder.<ref>{{cite web|title=Biological Causes of Anorexia Nervosa and Bulimia Nervosa|url=http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98-paper3/Hirst3.html|access-date=July 4, 2016|archive-url=https://web.archive.org/web/20160502145058/http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98-paper3/Hirst3.html|archive-date=May 2, 2016|url-status=dead}}</ref> Abnormal levels of many hormones, notably [[serotonin]], have been shown to be responsible for some disordered eating behaviors.{{Citation needed|date=January 2025}} [[Brain-derived neurotrophic factor]] (BDNF) is under investigation as a possible mechanism.<ref>{{cite journal | vauthors = Ribasés M, Gratacòs M, Fernández-Aranda F, Bellodi L, Boni C, Anderluh M, Cavallini MC, Cellini E, Di Bella D, Erzegovesi S, Foulon C, Gabrovsek M, Gorwood P, Hebebrand J, Hinney A, Holliday J, Hu X, Karwautz A, Kipman A, Komel R, Nacmias B, Remschmidt H, Ricca V, Sorbi S, Wagner G, Treasure J, Collier DA, Estivill X | display-authors = 6 | title = Association of BDNF with anorexia, bulimia and age of onset of weight loss in six European populations | journal = Human Molecular Genetics | volume = 13 | issue = 12 | pages = 1205–12 | date = June 2004 | pmid = 15115760 | doi = 10.1093/hmg/ddh137 | doi-access = free }}</ref><ref>{{cite book|title=Annual Review of Eating Disorders&nbsp;– part 2 |year=2018 |veditors = Wonderlich S, Mitchell JE, de Zwaan M, Steiger H|publisher=Radcliffe Publishing|pages=14–15|chapter=Psychobiology of eating disorders |chapter-url=https://books.google.com/books?id=3UxWDwAAQBAJ&pg=PT15 |isbn=978-1-84619-244-9}}</ref>

There is evidence that sex hormones may influence appetite and eating in women and the onset of bulimia nervosa. Studies have shown that women with [[hyperandrogenism]] and [[polycystic ovary syndrome]] have a dysregulation of appetite, along with carbohydrates and fats. This dysregulation of appetite is also seen in women with bulimia nervosa. There is evidence that there is an association between polymorphisms in the ERβ ([[estrogen receptor]] β) and bulimia, suggesting there is a correlation between sex hormones and bulimia nervosa.<ref>{{cite journal | vauthors = Hirschberg AL | title = Sex hormones, appetite and eating behaviour in women | journal = Maturitas | volume = 71 | issue = 3 | pages = 248–56 | date = March 2012 | pmid = 22281161 | doi = 10.1016/j.maturitas.2011.12.016 }}</ref>

Bulimia has been compared to drug addiction, though the empirical support for this characterization is limited.<ref>{{cite journal | vauthors = Broft A, Shingleton R, Kaufman J, Liu F, Kumar D, Slifstein M, Abi-Dargham A, Schebendach J, Van Heertum R, Attia E, Martinez D, Walsh BT | display-authors = 6 | title = Striatal dopamine in bulimia nervosa: a PET imaging study | journal = The International Journal of Eating Disorders | volume = 45 | issue = 5 | pages = 648–56 | date = July 2012 | pmid = 22331810 | pmc = 3640453 | doi = 10.1002/eat.20984 }}</ref> However, people with bulimia nervosa may share dopamine D2 receptor-related vulnerabilities with those with [[substance use disorder]]s.<ref>{{cite journal | vauthors = Kaye WH, Wierenga CE, Bailer UF, Simmons AN, Wagner A, Bischoff-Grethe A | title = Does a shared neurobiology for foods and drugs of abuse contribute to extremes of food ingestion in anorexia and bulimia nervosa? | journal = Biological Psychiatry | volume = 73 | issue = 9 | pages = 836–42 | date = May 2013 | pmid = 23380716 | pmc = 3755487 | doi = 10.1016/j.biopsych.2013.01.002 }}</ref>

Dieting, a common behaviour in bulimics, is associated with lower plasma tryptophan levels.<ref>{{cite journal | vauthors = Strasser B, Fuchs D | title = Diet Versus Exercise in Weight Loss and Maintenance: Focus on Tryptophan | journal = International Journal of Tryptophan Research | volume = 9 | pages = 9–16 | year = 2016 | pmid = 27199566 | pmc = 4864009 | doi = 10.4137/IJTR.S33385 }}</ref> Decreased tryptophan levels in the brain, and thus the synthesis of serotonin, such as via [[acute tryptophan depletion]], increases bulimic urges in currently and formerly bulimic individuals within hours.<ref>{{cite journal | vauthors = Smith KA, Fairburn CG, Cowen PJ | title = Symptomatic relapse in bulimia nervosa following acute tryptophan depletion | journal = Archives of General Psychiatry | volume = 56 | issue = 2 | pages = 171–6 | date = February 1999 | pmid = 10025442 | doi = 10.1001/archpsyc.56.2.171 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Weltzin TE, Fernstrom MH, Fernstrom JD, Neuberger SK, Kaye WH | title = Acute tryptophan depletion and increased food intake and irritability in bulimia nervosa | journal = The American Journal of Psychiatry | volume = 152 | issue = 11 | pages = 1668–71 | date = November 1995 | pmid = 7485633 | doi = 10.1176/ajp.152.11.1668 }}</ref>

Abnormal blood levels of peptides important for the regulation of appetite and energy balance are observed in individuals with bulimia nervosa, but it remains unknown if this is a state or trait.<ref>{{cite journal | vauthors = Tortorella A, Brambilla F, Fabrazzo M, Volpe U, Monteleone AM, Mastromo D, Monteleone P | title = Central and peripheral peptides regulating eating behaviour and energy homeostasis in anorexia nervosa and bulimia nervosa: a literature review | journal = European Eating Disorders Review | volume = 22 | issue = 5 | pages = 307–20 | date = September 2014 | pmid = 24942507 | doi = 10.1002/erv.2303 }}</ref>

In recent years, [[evolutionary psychiatry]] as an emerging scientific discipline has been studying [[mental disorder]]s from an evolutionary perspective. If eating disorders, Bulimia nervosa in particular, have evolutionary functions or if they are new modern "lifestyle" problems is still debated.<ref name="pmid9875960">{{cite journal | vauthors = Abed RT | title = The sexual competition hypothesis for eating disorders | journal = Br J Med Psychol | volume = 71 ( Pt 4) | issue = 4| pages = 525–47 | date = December 1998 | pmid = 9875960 | doi = 10.1111/j.2044-8341.1998.tb01007.x }}</ref><ref name="pmid30429818">{{cite journal | vauthors = Nettersheim J, Gerlach G, Herpertz S, Abed R, Figueredo AJ, Brüne M | title = Evolutionary Psychology of Eating Disorders: An Explorative Study in Patients With Anorexia Nervosa and Bulimia Nervosa | journal = Front Psychol | volume = 9 | issue = | pages = 2122 | date = 2018 | pmid = 30429818 | pmc = 6220092 | doi = 10.3389/fpsyg.2018.02122 | doi-access=free }}</ref><ref>{{cite book |vauthors = Nesse RM |title=Good reasons for bad feelings: insights from the frontier of evolutionary psychiatry |date=2020 |publisher=Penguin Books, Limited |isbn=978-0-14-198491-9 |oclc=1100591660 }}{{page needed|date=July 2021}}</ref>

===Social===

Media portrayals of an 'ideal' body shape are widely considered to be a contributing factor to bulimia.<ref name=Barker03/> In a 1991 study by Weltzin, Hsu, Pollicle, and Kaye, it was stated that 19% of bulimics undereat, 37% of bulimics eat an average or normal amount of food, and 44% of bulimics overeat.<ref>{{cite book |title=Psychology: the science of behaviour |edition=4th Canadian |first1=Neil R. |last1=Carlson |first2=William |last2=Buskist |first3=C. Donald |last3=Heth |first4=Rod |last4=Schmaltz | name-list-style = vanc |year=2010 |publisher=Pearson Education Canada |location=Toronto |isbn=978-0-205-70286-2 |page=415 <!-- Updated info from http://catalogue.pearsoned.ca/product?ISBN=9780205702862 -->}}</ref> A survey of 15- to 18-year-old high school girls in [[Nadroga-Navosa Province|Nadroga]], [[Fiji]], found the self-reported incidence of purging rose from 0% in 1995 (a few weeks after the introduction of television in the province) to 11.3% in 1998.<ref>{{cite journal | vauthors = Becker AE, Burwell RA, Gilman SE, Herzog DB, Hamburg P | title = Eating behaviours and attitudes following prolonged exposure to television among ethnic Fijian adolescent girls | journal = The British Journal of Psychiatry | volume = 180 | issue = 6 | pages = 509–14 | date = June 2002 | pmid = 12042229 | doi = 10.1192/bjp.180.6.509 | doi-access = free }}</ref> In addition, the suicide rate among people with bulimia nervosa is 7.5 times higher than in the general population.<ref>Nolen-Hoeksema, Susan (2014). [http://connect.mheducation.com/connect/hmEBook.do?setTab=sectionTabs "Bulimia Nervosa"] ''Abnormal Psychology''. 6e. pg 344.</ref>

When attempting to decipher the origin of bulimia nervosa in a cognitive context, [[Christopher Fairburn]] ''et al.''{{'}}s cognitive-behavioral model is often considered the golden standard.<ref>{{cite journal | vauthors = Cooper Z, Fairburn CG | title = The Evolution of "Enhanced" Cognitive Behavior Therapy for Eating Disorders: Learning From Treatment Nonresponse | journal = Cognitive and Behavioral Practice | year=2013 | volume = 18 | issue = 3 | pages = 394–402 | doi = 10.1016/j.cbpra.2010.07.007 | pmid = 23814455| pmc = 3695554 }}</ref> Fairburn et al.'s model discusses the process in which an individual falls into the binge-purge cycle and thus develops bulimia. Fairburn ''et al.'' argue that extreme concern with weight and shape coupled with low self-esteem will result in strict, rigid, and inflexible dietary rules. Accordingly, this would lead to unrealistically restricted eating, which may consequently induce an eventual "slip" where the individual commits a minor infraction of the strict and inflexible dietary rules. Moreover, the cognitive distortion due to [[dichotomy|dichotomous]] thinking leads the individual to binge. The binge subsequently should trigger a perceived loss of control, promoting the individual to purge in hope of counteracting the binge. However, Fairburn ''et al.'' assert the cycle repeats itself, and thus consider the binge-purge cycle to be self-perpetuating.<ref>{{cite journal | vauthors = Fairburn CG, Beglin SJ | title = Studies of the epidemiology of bulimia nervosa | journal = The American Journal of Psychiatry | volume = 147 | issue = 4 | pages = 401–8 | date = April 1990 | pmid = 2180327 | doi = 10.1176/ajp.147.4.401 }}</ref>

In contrast, Byrne and Mclean's findings differed slightly from Fairburn ''et al.''{{'}}s cognitive-behavioral model of bulimia nervosa in that the drive for thinness was the major cause of purging as a way of controlling weight. In turn, Byrne and Mclean argued that this makes the individual vulnerable to binging, indicating that it is not a binge-purge cycle but rather a purge-binge cycle in that purging comes before bingeing. Similarly, Fairburn ''et al.''{{'}}s cognitive-behavioral model of bulimia nervosa is not necessarily applicable to every individual and is certainly reductionist. Every one differs from another, and taking such a complex behavior like bulimia and applying the same one theory to everyone would certainly be invalid. In addition, the cognitive-behavioral model of bulimia nervosa is very culturally bound in that it may not be necessarily applicable to cultures outside of Western society. To evaluate, Fairburn ''et al.''.'s model and more generally the cognitive explanation of bulimia nervosa is more descriptive than explanatory, as it does not necessarily explain how bulimia arises. Furthermore, it is difficult to ascertain cause and effect, because it may be that distorted eating leads to distorted cognition rather than vice versa.<ref>{{cite book|last=Trull|first=Thimothy| name-list-style = vanc |title=Abnormal Psychology and Life: A Dimensional Approach|publisher=Wadsworth, Cengage Learning|location=Belmont CA|isbn=978-1-111-34376-7|pages=236–8|url=https://books.google.com/books?id=0kEcIFJUk64C&pg=PA236|date=2010-10-08|url-status=live|archive-url=https://web.archive.org/web/20160207044917/https://books.google.com/books?id=0kEcIFJUk64C&pg=PA236|archive-date=2016-02-07}}</ref><ref>{{cite journal | vauthors = Byrne SM, McLean NJ | title = The cognitive-behavioral model of bulimia nervosa: a direct evaluation | journal = The International Journal of Eating Disorders | volume = 31 | issue = 1 | pages = 17–31 | date = January 2002 | pmid = 11835294 | doi = 10.1002/eat.10002 }}</ref>

A considerable amount of literature has identified a correlation between sexual abuse and the development of bulimia nervosa. The reported incident rate of unwanted sexual contact is higher among those with bulimia nervosa than anorexia nervosa.<ref>{{cite journal | vauthors = Waller G | title = Sexual abuse and the severity of bulimic symptoms | journal = The British Journal of Psychiatry | volume = 161 | pages = 90–3 | date = July 1992 | pmid = 1638336 | doi = 10.1192/bjp.161.1.90 | s2cid = 39739310 }}</ref>

When exploring the etiology of bulimia through a socio-cultural perspective, the "thin ideal internalization" is significantly responsible. The thin-ideal internalization is the extent to which individuals adapt to the societal ideals of attractiveness. Studies have shown that young women that read fashion magazines tend to have more bulimic symptoms than those women who do not. This further demonstrates the impact of media on the likelihood of developing the disorder.<ref name=Abnormal>{{cite book|last=Nolen-Hoeksema|first=Susan| name-list-style = vanc |title=(Ab)normal Psychology|date=2013|publisher=McGraw Hill|isbn=978-0078035388|page=338}}</ref> Individuals first accept and "buy into" the ideals, and then attempt to transform themselves in order to reflect the societal ideals of attractiveness. J. Kevin Thompson and Eric Stice claim that family, peers, and most evidently media reinforce the thin ideal, which may lead to an individual accepting and "buying into" the thin ideal. In turn, Thompson and Stice assert that if the thin ideal is accepted, one could begin to feel uncomfortable with their body shape or size since it may not necessarily reflect the thin ideal set out by society. Thus, people feeling uncomfortable with their bodies may result in body dissatisfaction and may develop a certain drive for thinness. Consequently, body dissatisfaction coupled with a drive for thinness is thought to promote dieting and negative effects, which could eventually lead to bulimic symptoms such as purging or bingeing. Binges lead to self-disgust which causes purging to prevent weight gain.<ref>{{cite web|last=Zieve|first=David| name-list-style = vanc |title=Bulimia|url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001381/|publisher=PubMed Health|access-date=April 18, 2011|url-status=live|archive-url=https://web.archive.org/web/20110211185310/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001381|archive-date=February 11, 2011}}</ref>

A study dedicated to investigating the thin ideal internalization as a factor of bulimia nervosa is Thompson's and Stice's research. Their study aimed to investigate how and to what degree media affects the thin ideal internalization. Thompson and Stice used randomized experiments (more specifically programs) dedicated to teaching young women how to be more critical when it comes to media, to reduce thin-ideal internalization. The results showed that by creating more awareness of the media's control of the societal ideal of attractiveness, the thin ideal internalization significantly dropped. In other words, less thin ideal images portrayed by the media resulted in less thin-ideal internalization. Therefore, Thompson and Stice concluded that media greatly affected the thin ideal internalization.<ref name="Sage journals online">{{cite journal |doi=10.1111/1467-8721.00144 |title=Thin-Ideal Internalization: Mounting Evidence for a New Risk Factor for Body-Image Disturbance and Eating Pathology |year=2001 |last1=Thompson |first1=J. Kevin |last2=Stice |first2=Eric| name-list-style = vanc  |journal=Current Directions in Psychological Science |volume=10 |issue=5 |pages=181–3 |jstor=20182734|s2cid=20401750 }}</ref> Papies showed that it is not the thin ideal itself, but rather the self-association with other persons of a certain weight that decide how someone with bulimia nervosa feels. People that associate themselves with thin models get in a positive attitude when they see thin models and people that associate with overweight get in a negative attitude when they see thin models. Moreover, it can be taught to associate with thinner people.<ref name="Papies">{{cite journal | vauthors = Papies EK, Nicolaije KA | title = Inspiration or deflation? Feeling similar or dissimilar to slim and plus-size models affects self-evaluation of restrained eaters | journal = Body Image | volume = 9 | issue = 1 | pages = 76–85 | date = January 2012 | pmid = 21962524 | doi = 10.1016/j.bodyim.2011.08.004 }}</ref>