Steele Children’s
Exposure to Siblings, Mother’s
Allergies, and Daycare Alter
Infant Cortisol Stress
Response
April 5, 2006
Contact: Darci Slaten,
520-626-7217
It has long been believed that the stress of chronic
immune diseases—like asthma—leads to increases in an individual’s cortisol
stress response. Cortisol is a hormone that is activated under stress and plays
an important role in many functions, including an individual’s immune function
and inflammatory response.
In a recently published study, Steele Children’s Research Center
investigator and lead author Thomas Ball,
MD, associate professor of clinical pediatrics at The University of Arizona and his colleagues found that
infants whose mothers have asthma or other allergic disease, had a higher
cortisol response to the stress of vaccination at 6 months of age than children
of mothers who do not have asthma or other allergic disease. This finding
demonstrates the impact of the intrauterine environment on the infant’s cortisol
stress response.
“This is very interesting and noteworthy because we’ve
historically attributed alterations of the cortisol stress response to be the
result of the stress of having
chronic disease,” explains Dr. Ball. “It now appears that the higher cortisol
stress response may precede the
onset of disease. Children of mothers with allergic diseases come into the world
with a higher cortisol setting—they have their ‘thermostat’ set higher. Because
of this higher cortisol stress response, these children appear at greater risk
of developing allergic diseases like asthma.”
The researchers also found that postnatal factors that
reduce the likelihood of an infant developing asthma and allergic diseases were
associated with a lower cortisol stress response. “We found that if infants had
older siblings, or attended daycare in the first two months of life, they had a
lower cortisol response to the stress of vaccination at 6 months,” says Dr.
Ball. This is consistent with the hygiene hypothesis, which proposes that
early exposure to microbes prevents the subsequent development of allergic
disease, since infants exposed to more children at home or in daycare have more
infections.
The first three years of life are critical to brain
development and because the “control center” for the cortisol stress response is
in the brain, it is believed that a child’s cortisol response to stress becomes
hard-wired during this time period.
“Since cortisol is so interrelated with the immune
system, the child’s early years are a critical window of opportunity for
impacting the development of their immune system,” explains Dr. Ball. “This is
the time when allergies often begin. If we can modify this response
through adequate control of maternal disease during pregnancy and by postnatal
exposure to external factors, such as daycare or siblings, we may be able to
reduce the likelihood of developing allergic
diseases.”
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sguthrie@email.arizona.edu
To read about the
expansion of the UA College of Medicine in Phoenix go to http://www.phoenix.medicine.arizona.edu/About/News/Campus/