By E.J. Mundell
NEW YORK, Mar 10 (Reuters Health) -- Women are much more likely than their
peers to develop anorexia or bulimia if their sister or mother already suffers
from the eating disorder, researchers report.
The finding suggests that a combination of "family-genetic influences play
an important role in determining susceptibility to eating disorders," explained
study lead author Dr. Michael Strober of the University of Pittsburgh,
Pennsylvania. His team published their findings in the March issue of the
American Journal of Psychiatry.
The researchers compared rates of eating disorders among the family members
of 323 women (aged 18 to 28 years) with anorexia or bulimia with the rates in
family members of 181 healthy women the same age.
The results? According to Strober, "The rate of bulimia nervosa and anorexia
nervosa amongst female relatives of persons with eating disorders was between 4
and 11 times higher, (respectively)," compared with the incidence of these
illnesses in women without relatives with the eating disorder. The rates for
eating disorders among male relatives did not appear to be affected by family
members' eating disorders.
Strober told Reuters Health that "milder forms of anorexia nervosa and
bulimia nervosa" -- in which individuals seem morbidly preoccupied with weight
and food, but have not yet lost dangerous amounts of weight -- "also seemed to
run together in families."
In a second study, Dr. Tracey Wade and colleagues at Virginia Commonwealth
University in Richmond, examined rates of anorexia and depression among over
2,100 female twins (both identical and fraternal). Overall, 77 (3.6%) of the
women had been diagnosed as suffering from anorexia, with 6 women having a twin
who shared this diagnosis.
Numerous studies have suggested that genes may predispose individuals to
depression. Wade's team speculates that these latest findings "strongly suggest
that genetic factors also influence the risk for anorexia nervosa." They
estimate that genetic factors may contribute to 58% of the risk for the eating
disorder.
According to Strober's group, it remains unclear which factors play a more
important role -- family environment or genes -- when it comes to the
'clustering' of eating disorders within specific families. Strober notes,
however, that "current research is searching for more specific areas of the
genome that might be associated with risk to these conditions."
