Sex Hormones Implicated in Etiology of Eating Disorders
Twin studies explore factors related to development of disordered eating and anorexia nervosa
WEDNESDAY, Dec. 5 (HealthDay News) -- The higher incidence of anorexia nervosa in women compared to men may be related to intrauterine sex hormone exposure, according to a report published in the December issue of the Archives of General Psychiatry. A second study also points to the involvement of genetic effects in the development of disordered eating.
In the first study, Marco Procopio, M.D., of the University of Sussex in England, and colleagues analyzed results from a phone survey targeting members of the Swedish Twin Registry. The results confirm that anorexia nervosa is 10 times more common in women compared to men, but also reveal males with female twins have a higher incidence of anorexia nervosa than male twins of the same sex. The researchers speculate that the hormonal environment in utero, specifically related to the presence of a female fetus, is linked to the etiology of anorexia nervosa.
In the second study, Kelly L. Klump, Ph.D., of Michigan State University in East Lansing, and colleagues assessed 772 same-sex female twins (386 pairs) from the Minnesota Twin Family Study using the Minnesota Eating Behavior Survey. The investigators found that etiologic influences on disordered eating change with age, with genetic factors having negligible influence in early adolescence (6 percent at age 11 years), then emerging as a much more dominant factor by mid-adolescence, contributing to roughly half of the variance (46 percent at ages 14 and 18).
"The increase in genetic effects during this developmental stage corroborates previous research implicating puberty in the genetic etiology of eating disorders," state Klump and colleagues. They also acknowledge that "increases in genetic effects from age 11 to 14 years may be the result of the potentiation of genetic risk by psychosocial risk factors (i.e., cultural pressures for thinness, increased family conflict) that may emerge or increase between early and middle adolescence."