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.  

Works Cited

1) http://en.wikipedia.org/wiki/Anorexia_nervosa

2) http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/psychiatry/eating/table1.htm

3) http://www.newsweek.com/id/51592/page/1

4) http://www.nytimes.com/2007/12/11/health/research/11insi.html