Prevalence and long-term course of lifetime eating disorders in an adult Australian twin cohort.

OBJECTIVE: Few studies exist that have examined the spectrum and natural long-term course of eating disturbance in the community. We examine the lifetime prevalence and long-term course of anorexia nervosa (AN), bulimia nervosa (BN) and eating disorder not otherwise specified (EDNOS) in an adult female twin population.

METHOD: Female twins (n = 1002) from the Australian Twin Registry, aged 28-39 years, were assessed using the Eating Disorder Examination, revised to yield lifetime diagnostic information. For women with lifetime eating disorders, the assessment occurred, on average, 14.52 years (SD = 5.65) after onset of their disorder.

RESULTS: In accordance with other community studies, we found a 1.9% lifetime prevalence of AN, with an additional 2.4% who met the criteria for 'partial AN' (absence of amenorrhea). Criteria for BN were met by 2.9% of the women, an additional 2.9% of women met criteria for binge eating disorder, while 5.3% met criteria for purging disorder unaccompanied by binge eating (EDNOS-p). Eleven (7%) of the women with lifetime eating disorders had a current eating disorder. Each diagnostic group continued to be differentiated by current eating pathology from women without lifetime eating disorders. Although approximately 75% of the women had a good outcome, less than 50% of each diagnostic group was asymptomatic.

CONCLUSIONS: Eating disorders tend to improve over time often reaching subdiagnostic levels of severity, but only a minority of sufferers becomes asymptomatic. The DSM-IV diagnosis EDNOS needs to be considered in studies of the prevalence and course of eating disorders.