342 Feeding and Eating Disorders
individuals more likely have a longer duration of illness, and their clinical presentation may
include more signs and symptoms of long-stand ing disorder. Clinicians should not exclude
anorexia nervosa from the differential diag nosis solely on the basis of older age.
Many individuals have a period of changed ea ting behavior prior to full criteria for the
disorder being met. Some individuals with anorexia nervosa recover fully after a single
episode, with some ex hibiting a fluctuating pattern of weight gain followed by relapse,
and others experiencing a chronic course over many years. Hospitalization may be re-
quired to restore weight and to address medical complications. Most individuals with an-
orexia nervosa experience remission within 5 years of presentation. Among individuals
admitted to hospitals, overall remission rates may be lower. The crude mortality rate (CMR)
for anorexia nervosa is approximately 5% pe r decade. Death most commonly results from
medical complications associated with the disorder itself or from suicide.
Risk and Prognostic Factors 
Temperamental. Individuals who develop anxiety disorders or display obsessional
traits in childhood are at increased risk of developing anorexia nervosa.
Environmental. Historical and cross-cultural variab ility in the prevalence of anorexia
nervosa supports its association with cultures and settings in which thinness is valued. Oc-
cupations and avocations that encourage thinness, such as modeling and elite athletics, are
also associated with increased risk. 
Genetic and physiological. There is an increased risk of  anorexia nervosa and bulimia
nervosa among first-degree biolog ical relatives of individuals with the disorder. An in-
creased risk of bipolar and depressive diso rders has also been found among first-degree