What is Atypical Anorexia Nervosa (A-AN)?
A myth in eating disorders is that restrictive eating disorders including anorexia nervosa and ARFID are only are problematic at very low BMIs and % Ideal Body Weight (IBW). The reality is that disordered eating and resulting medical complications can occur with previously overweight patients who present with major absolute weight loss over a short time. This is called Atypical Anorexia Nervosa (A-AN), also known as "weight suppression."
ACUTE is treating a growing number of patients with A-AN, whose current weight is normal or above normal but who are experiencing the same life-threatening medical issues seen in anorexia nervosa (AN) with severely low body weight. Each case is evaluated carefully, including percentage of body weight loss, magnitude and rate of weight loss (time frame), in the context of absolute current weight.
Atypical Anorexia Nervosa Symptoms & Signs
All criteria for AN are met, except that despite significant weight loss, the individual’s presentation weight is within or above the normal range.
- Current BMI, % IBW normal or above normal
- Recent rapid, massive weight loss
- Too fast: < 3-6 months for duration of weight
- Too much: losing > 25% of premorbid weight
- Drive for thinness, body image distortions
Atypical Anorexia Nervosa Medical Complications
Myocardial atrophy, mitral valve prolapse, pericardial effusion, sinus bradycardia, profound irreversible sinus node dysfunction, orthostatic hypotension, sudden cardiac death
Gastroparesis, constipation, superior mesenteric artery (SMA) syndrome, diarrhea, liver disease, functional bowel disorders
Spontaneous pneumothorax and pneumomediastinum, aspiration pneumonia, abnormal pulmonary function tests
Low White Blood Cell, Red Blood Cell, Platelet Counts
Multiple Endocrine Abnormalities
Low leptin levels, growth hormone resistance, elevated serum cortisol levels, euthyroid sick syndrome, hypoglycemia, amenorrhea
Loss of Muscle and Bone
Sarcopenia, bone loss (osteopenia and osteoporosis)
Generalized brain atrophy, cognitive deficits
Xerosis, acrocyanosis, lanugo hair growth, brittle hair and nails and unexplained hypercarotenemia
Atypical Anorexia Nervosa Facts
- Atypical Anorexia Nervosa is now officially classified under the category of “other specified eating disorders,” in the DSM-5.
- Despite official clinical recognition, atypical anorexia nervosa is under-recognized and widely perceived to be less severe than anorexia nervosa.
- Patients with atypical anorexia nervosa can have just as severe or more severe medical complications as classic anorexia nervosa, with slight differences; for example, no alteration in gray matter, and less likely to experience loss of menses.
- Atypical anorexia nervosa diagnosis requires both significant, rapid weight loss AND cognitive concern, AKA “weight suppression.”
- The prevalence of atypical anorexia nervosa by age 20 years is 28% (vs < 1% for anorexia nervosa).
- Patients with atypical anorexia nervosa are less likely to receive inpatient treatment.
- Patients with atypical anorexia nervosa experience the same incidence of binge eating, purging, psychiatric comorbidity, use of psychotropic medications, self- harm, suicidal ideation, severe depressive symptoms, and obsessive/ compulsiveness as classic anorexia nervosa.
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