Anorexia Nervosa Is Common But Often Transient

HELSINKI, Finland, Aug. 1 -- The prevalence of anorexia is greater than previously thought, but so is recovery, according to a Finnish twin study.

By age 30, up to 70% of Finnish women with anorexia nervosa had recovered from the eating disorder, Anna Keski-Rahkonen, M.D., Ph.D., of the University of Helsinki and Columbia University, and colleagues reported in the Aug. 1 issue of the American Journal of Psychiatry.

In the nationwide study of 2,881 women surveyed from the 1975-1979 birth cohorts, the researchers found anorexia rates to be twice as high as those previously cited.

Overall, they found that 2.2% had severe anorexia and, when less severe forms of the disorder (no amenorrhea, for example) were included, about 5% of women were afflicted with the eating disorder during their lifetime, the researchers said.

The rate among women ages 15 to 19, the peak interval of risk, was 270/100,000 person years. Other studies have shown that rate to be much lower-136/100,000 person-years in the U.S., for example, the researchers said.

However, it has been estimated that only about half of all cases of anorexia are detected by primary care physicians and that only about a third receive mental health care.

Thus the "natural" course of the disease remains poorly understood, and the incidence has been substantially underestimated in previous studies, Dr. Anna Keski-Rahkonen said.

She and her colleagues found that only half of the women who reported being anorexic were recognized as such by healthcare professionals, suggesting a much higher prevalence of the eating disorder.

Despite the grim mortality rates (about 5.6% per decade) and length of illness reported elsewhere, the researchers also found that by age 28, up to 70% of women had recovered.

The average duration of anorexia was three years. Overall, about 66.8% of women with severe disease recovered within five years from the onset of symptoms, and more than 70%, including those with less severe disease, recovered during the study time. About 25% recovered within a year and about 33% within two years.

The researchers said they did not assess mortality because the number of cases was small and follow-up was limited to age 22 to 28. Only a third of the women (38) with severe anorexia had symptoms longer than five years, and only 8.4% (19) had symptoms beyond 10 years.

However, it is worth noting, they said, that overall mortality in this cohort was low, with only eight deaths recorded from age 16 to the assessment between ages 22 and 28.

Within five years of regaining a healthy weight, the anorexic twins were virtually indistinguishable from their healthy co-twins or healthy women in the general population in terms of psychological symptoms and self esteem.

However, learning to deal with body shape and weight-related concerns usually took five to 10 years.

The researchers noted study limitations that included retrospective assessment of lifetime diagnoses by phone, incomplete recall, and lack of face-to-face contacts, which may have led to an underestimation of lifetime prevalences.

The five-year clinical recovery rates were similar for the detected and undetected cases and detection of anorexia by the health care system had no association with prognosis in the study. However, the authors noted that the impact of treatment outcome could not be directly assessed in this study "because case detection does not necessarily imply proper treatment."