What Causes Anorexia?
When I read an article in The New York Times that said researchers had found evidence to support the
idea that anorexia may have a biological basis, I was initially surprised but then this idea started to
make sense. In this class we have talked about how the nature verse nurture debate has already been
solved—and that the answer is both nature and nurture. We talked about how genes and the environment
work together to form the people we are, and a disease such as Anorexia is not an exception. It is pretty
obvious how the environment contributes to causing this disease, especially in American culture. Just turn
on the television or read a magazine; women (and men) are surrounded by impossible expectations. The
pressure to meet these standards, especially for young women trying to discover who they are, can be
unbearable. Anorexia research has been so fixated on the cultural causes that it is now interesting to watch
as scientists take a step back and try a different approach in examining the genetic factors that may be
connected with this disorder.
Anorexia nervosa is a psychiatric disorder defined by the Diagnostic and Statistical Manual of Mental
disorders as a refusal to maintain body weight at or above a minimally normal weight for age and height
combined with an intense fear of gaining weight and in females, the absence of at least three menstrual
cycles. This disorder usually affects adolescent females, but approximately ten percent of people affected are
male. It can lead to heart problems, immune dysfunction and ultimately, death. Historically, the
psychological causes of this disorder have been focused on, such as the idea that young girls with extreme
pressures on them choose extreme dieting as a way to control their lives, but new studies show that genetics
may be a contributing factor.
A study published by researchers at Virginia Commonwealth University looked at 2,163 female twins
and found that 77 of them suffered from symptoms of anorexia. They then compared the number of
identical twins who had anorexia with the significantly smaller number of fraternal twins who had it and
concluded that more than fifty percent of the risk of developing anorexia is genetic.
Another study by Dr. Marco Procopio suggests that female sex hormones in the womb may play a part
in finding the biological cause of anorexia. Researchers used the Swedish twin registry to study 4,226 pairs
of female twins, 3,451 pairs of male twins and 4,478 pairs of opposite-sex twins, all born from 1935 to
1958. They found fifty-one cases of anorexia among the female twins and thirty-six among the opposite sex
pairs. Three cases were found among the male twins. This study showed that males have a higher risk of
becoming anorexic if they are part of a pair of opposite sex twins. The statistical risk for these males was no
different from the risk among females. This caused researchers to conclude that the shared intrauterine
environment of male-female twin pairs is what leads to the increased risk for the males. They think female
sex hormones influence neurodevelopment and cause this increased risk of anorexic behavior.
Other researchers at the University of Pittsburgh are looking at brain scans of anorexic patients to see if
brain chemistry might be different in these patients. They have discovered abnormally high levels of
seratonin activity in anorexics. Although this hormone usually causes feelings of well being, high levels can
cause anxiety and obsessive thinking which typically affect anorexic patients. Starvation may be a
self-medication technique, because starvation prevents an essential amino acid that produces serotonin from
getting into the brain, and reduces seratonin levels.
This does not mean that the environment plays no part in causing anorexia. Many scientists think of
our culture as a trigger for the disease. Impossible standards and overwhelming pressure combined with a
genetic or biological predisposition can lead to unhealthy ways of dealing with their problems; including
anorexia. As the age of onset for anorexia becomes younger and younger it is important to learn as much
we can about this disorder so we can find a treatment. Also, as we find out more and more that
psychological disorders have a biological basis it makes one wonder how the field of psychology will change
with this new knowledge.