Etiology
The etiology of bulimia nervosa is uncertain. A biopsychosocial theory of causation posits a combination of coexisting biologic (genetic abnormalities in receptors or neurotransmitters), psychological, and social factors.[11][13][14][15]
Risk factors that are strongly associated with bulimia nervosa include female sex; perfectionism; body dissatisfaction; impulsivity; history of sexual abuse; family history of alcoholism, depression, or eating disorder; past obesity; and exposure to media pressure. An association with urbanization has been reported.[16] Family history of obesity is considered a weak predictor.[17] Early onset of puberty is associated with early onset of bulimia nervosa.[18]
Pathophysiology
The pathophysiology of bulimia nervosa is unknown. However, evidence suggests that people may binge and purge when they have low self-esteem, when they are pressured to conform to eating or to adhere to a specific weight and shape, and when they are knowledgeable about binge eating and purging. Compensatory behaviors such as vomiting, use of laxatives, or exercise may result in large fluctuations in weight that reinforce the behavior.[11] These behaviors can result in erosion of the teeth; parotid and submandibular gland hypertrophy; esophageal reflux, dysmotility, or spasm; gastric dysmotility; bowel irregularity; volume depletion; cardiac arrhythmia; and metabolic abnormalities such as hypokalemia or hypomagnesemia.
Classification
Diagnostic and statistical manual of mental disorders (DSM-5-TR)[1]
Bulimia nervosa is included in the category "Feeding and Eating Disorders".
Bulimia nervosa is characterized by recurrent episodes of binge eating and recurrent inappropriate compensatory behaviors in order to prevent weight gain.
During an episode of binge eating, people with bulimia eat, in a discrete period of time, a quantity of food that is definitely larger than what most people would eat in a similar period under similar circumstances. They also experience a sense that they cannot control what or how much they are eating, or cannot stop eating.
Inappropriate compensatory behaviors include self-induced vomiting, fasting, excessive exercise, or misuse of laxatives, diuretics, or other medications.
Patients with bulimia nervosa are no longer subtyped into one of two categories based on the type of compensatory behavior, because data do not support the clinical utility of this distinction.[2] Formerly, there had been a purging type (i.e., regular engagement in self-induced vomiting or the misuse of laxatives, diuretics, or enemas) and a nonpurging type (e.g., fasting or excessive exercise, but not self-induced vomiting or misuse of laxatives, diuretics, or enemas).
Bulimia nervosa is characterized by the presence of at least one bulimic episode per week, on average, for a 3-month period (instead of two episodes/week over a 6-month period as in DSM-IV).
A severity specifier has been added to DSM-5-TR that is based on the average number of inappropriate compensatory behaviors/week: mild = 1-3 episodes/week; moderate = 4-7 episodes/week; severe = 8-13 episodes/week; and extreme = 14 or more episodes/week. The severity can be increased to reflect higher degrees of functional disability or other symptoms.
The category "Eating Disorder Not Otherwise Specified" (EDNOS) no longer exists. Instead, the category "Other Specified Feeding or Eating Disorder" (OSFED) indicates the presence of disordered eating causing clinically significant distress but not meeting full criteria for any of the feeding and eating disorders. The category "Unspecified Feeding or Eating Disorder" (UFED) is for disordered eating that is not more accurately captured by OSFED.
International classification of diseases, 11th revision (ICD-11)[3]
ICD-11 has a section on feeding or eating disorders. Within this, it characterizes bulimia nervosa (6B81) as frequent, recurrent episodes of binge eating (once a week or more for over 1 month). Binge eating is defined as a period of time where the individual has loss of control over their eating behavior and feels unable to stop. In bulimia nervosa, binge eating episodes are accompanied by compensatory behaviors to prevent weight gain, for example laxative use or vomiting. The individual is also preoccupied by weight or shape and does not meet the diagnostic criteria for anorexia.
ICD-11 has a separate category for binge eating disorder (6B82), characterized, like in bulimia, with periods of loss of control over eating. Unlike bulimia nervosa, however, these episodes are not followed by compensatory behaviors to prevent weight gain.
Another category in ICD-11 is rumination-regurgitation disorder (6B85). This disorder is characterized by the intentional and repeated bringing up of previously swallowed food back to the mouth (i.e., regurgitation), which may be rechewed and reswallowed (i.e. rumination), or may be deliberately spat out (but, differentiating it from bulimia nervosa, is not vomited). The regurgitation behavior is frequent (at least several times per week) and sustained over a period of at least several weeks. It is only diagnosed in those at least 2 years old.
Features compared with other eating disorders
Anorexia nervosa is distinguished from bulimia by the presence of either an intense fear of gaining weight or of becoming fat, or persistent behaviors that interfere with weight gain, despite being significantly underweight. Body mass index and body fat are usually required to be low to meet criteria for anorexia nervosa, whereas patients with bulimia nervosa may be of normal weight.[4] Both bulimia nervosa and anorexia nervosa may have binge and purge behaviors; individuals whose binge-eating behavior occurs only during episodes of anorexia nervosa are diagnosed as anorexia nervosa binge-eating/purging type and should not be given a diagnosis of bulimia nervosa.
As noted above, the "Other Specified Feeding or Eating Disorder" (OSFED) category includes disordered eating that negatively affects normal functioning but does not meet criteria for bulimia nervosa, anorexia nervosa, binge-eating disorder, or another feeding or eating disorder. For example, a patient might purge in the absence of binge eating or might meet all the criteria for bulimia nervosa except that bulimic episodes occur fewer than once per week and/or for a duration of less than 3 months.
Binge-eating disorder is distinguished from bulimia by the lack of compensatory behaviors. Most patients with binge-eating disorder are obese. Most patients with bulimia nervosa are within the normal weight range.
Rumination-regurgitation disorder (ICD-11) is differentiated from bulimia nervosa in that regurgitated food is either rechewed and reswallowed or spat out, but not vomited. In addition, as part of the DSM-5-TR criteria for rumination disorder, the behavior cannot be exclusively related to an eating disorder intended to control weight.
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