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1992.03.27 :  Research Finding -- Bulimia Nervosa

Contact: Sophia P. Glezos (301) 443-4536
March 27, 1992

       Bulimia nervosa, a sometimes life-threatening eating
disorder of unknown cause, is associated with excessive levels of
the brain hormone vasopressin, scientists at the National
Institute of Mental Health have found.
       This finding may lead to the development of effective
medications for people with the disorder, which involves
disabling obsessive thinking and compulsive behaviors.  It also
adds to mounting evidence, derived through earlier studies by the
same scientists, that implicates excessive vasopressin in two
other disorders with obsessive-compulsive features: the related
eating disorder anorexia nervosa and obsessive compulsive
disorder (OCD).
       Symptoms of bulimia nervosa are compulsive binge-eating
and stringent methods to avoid weight gain such as vomiting and
excessive use of laxatives, and obsessive preoccupation with food
and body image.  The condition affects 2 percent to 5 percent of
adolescent and young adult women.  
       The NIMH researchers examined the cerebrospinal fluid --
which bathes all brain nerve cells -- of 24 female patients with
bulimia nervosa and 11 healthy female volunteers.  On average,
they found abnormally high vasopressin levels in the
cerebrospinal fluid of the bulimia nervosa patients.

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       In the bloodstream, vasopressin regulates body fluid
levels and salt balance.  In the central nervous system, it is
thought to affect thirst, blood pressure, learning and memory.
       Scientists know that vasopressin is normally released in
response to physical and possibly emotional stress, said Philip
W. Gold, M.D., the paper's senior author and chief of the NIMH
Clinical Neuroendocrinology Branch.  "For unknown reasons, some
people may overproduce vasopressin when they're stressed, which
could put them at a higher risk for developing obsessive-
compulsive illnesses such as eating disorders and OCD," he said.
       The investigators' theory that excessive vasopressin may
contribute to obsessive-compulsive symptoms was based on earlier
animal studies.  The results had shown that vasopressin injected
into the cerebrospinal fluid of laboratory animals markedly
prolongs behavior learned under conditioned circumstances.  
       When an animal, for example, is exposed simultaneously to
a harmless light and a frightening loud sound, it will later
react with alarm in the presence of the light alone.  When the
animal is injected with vasopressin, this anxious response
persists longer than in animals not injected with vasopressin.
       "In the same way that vasopressin-injected animals take
longer than control animals to 'forget' that the light without
the loud noise has no frightening effect, too much vasopressin in
the brain may cause people to retain a learned association
longer," said the paper's first author Mark A. Demitrack, M.D., 
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previously with NIMH and now assistant professor of psychiatry at
the University of Michigan Medical School, Ann Arbor.
       "In bulimia nervosa patients, vasopressin may enhance the
conditioned cycle of rigorous dieting, compulsive overeating and
subsequent vomiting," Dr. Demitrack said.  "The resulting
avoidance of weight gain serves as the reward that reinforces the
patient's obsessive thinking about her body image."
       At present, there is no specific medical treatment for
bulimia nervosa, although a number of patients with the disorder
respond, at least partially, to certain types of antidepressant
or antianxiety medications.  
       NIMH Director Frederick K. Goodwin, M.D., said this study
is a "classic example of how certain environmental stressors can
act on biological substrates, or neurochemical underpinnings, to
play a role in the onset of mental illness -- in this case,
bulimia nervosa."
       The study was published in the April issue of the Journal
of Clinical Endocrinology and Metabolism.  Other authors on the
paper include Konstantine T. Kalogeras, M.D., Margaret Altemus,
M.D., Teresa A. Piggott, M.D., and Sam J. Listwak, B.S., NIMH. 



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