The study also gave evidence to support the fact that it's
not only social influences, but also biological factors that are associated
with such disorders.
The team of MSU psychology researchers, led by Kristen
Culbert, a doctoral student in clinical psychology and Kelly Klump, MSU
associate professor of psychology and president of the Academy for Eating
Disorders, are conducting this six-year study of 538 sets of twins in Michigan.
The findings of this study indicate that females who were in
the womb with male twins were less prone to a risk for eating disorder symptoms
than females who were in the womb with female twins. However, in an earlier
animal research it was shown that females in the womb with males are exposed to
higher levels of testosterone.
"From these findings, it appears that testosterone exposure
could have a protective effect against the development of disordered eating,"
The academy pointed out that 10 percent or more of late
adolescent and adult women report symptoms of eating disorders at any given
According to Klump, it's been long known that women are more
affected by eating disorders than men and that "some of that is due to social
influences such as beauty ideals around thinness for women that we don't have
for men." But, the influence of biological factors has not been studied much.
Klump said that the fast-growing MSU Twin Registry,
including more than 1,200 sets of twins ages 6 to 30, provided a substantial
Culbert said that while societal differences have typically
been used to explain why women are more affected by eating disorders, the new
research is "significant in suggesting a biological explanation."
Adding, he said that being raised with a brother did not
account for the effects and that's because researchers also examined females
who were not twins but grew up with a brother and discovered that those females
were at higher risk for eating disorder symptoms than females who shared a womb
with and were raised with a male.
Klump said that the findings could ultimately help improve
the treatment of eating disorders.
"More and more animal researchers are discovering how
testosterone affects brain development. So if we know there are protective
factors against eating disorders, we can potentially determine which areas of
the brain might be particularly sensitive to prenatal testosterone exposure and
use that information to identify new biological treatments," she said.
The findings are published in the recent issue of the
Archives of General Psychiatry.