Scientist Studies How Secondhand Smoke Changes Brain Chemistry
Children who are raised in households with secondhand smoke
are at increased risk for developing respiratory diseases of which
a cough is a major and frequent symptom. Samuel Evans, MD, is
trying to better understand how receptors and chemicals in the
brain and lung control cough, hoping to show how exposure to tobacco
smoke can change the brain's chemistry.
Coughing is symptomatic of most lung diseases, including asthma,
chronic bronchitis, influenza and tuberculosis. It is a complex
defensive reflex that occurs in response to foreign material and
irritants, including mucus, stimulating sensory receptors in the
airways.
"When you accidentally breathe in a drop of water, I'm sure
you've noticed a vigorous cough in response to expel the foreign
material," the researcher explains. "That drop of water
likely stimulated airway receptors, which then sent information
to the brain to coordinate the muscle contractions, diaphragm
movement, and throat closure required to cough."
The first area to receive the sensory information from the lungs
is located in the brain stem. The information is sorted and then
sent to higher centers of the brain. Within this circuitry, there
are numerous types of connections and neurotransmitters that help
organize the information that ultimately triggers a cough. Dr.
Evans is studying a specific neurotransmitter in the brain stem.
He works in the laboratory of Jesse Joad, MD, at the University
of California, Davis, which recently had its study showing that
tobacco smoke may indeed change the brain's chemistry published
in the American Journal of Respiratory and Critical Care Medicine.
Dr. Evans will present some preliminary results from his project
at the American Thoracic Society's Annual Meeting in May.
Research Could Lead to Better Cough Remedies
Dr. Evans, who is a fellow at UC Davis in Pulmonary and Critical
Care Medicine, treats patients nearly every day and knows all
too well the effect coughing has on their quality of life.
"Coughing is a very bothersome and common complaint for
which millions are spent on suppressive remedies, most of which
currently are only marginally, if at all, effective," he
says. "In order to better treat cough, and perhaps some of
the diseases that cause it, we need to better understand the mechanisms
that control the behavior."
Dr. Evans received a grant from the American Lung Association
of California to conduct his study. This year the association
granted more than $750,000 to researchers like Dr. Evans who are
conducting basic research into the underlying mechanisms of lung
disease. Basic research is an important investment because discoveries
made today can lead to better treatments and possibly even cures.
Californians can invest in lung disease research through the
Asthma and Lung Disease Research Fund on their 2003 California
state income tax returns. The fund is located under Contributions
and the money supports the American Lung Association of California's
peer-reviewed research program. For more information about the
Asthma and Lung Disease Research Fund and a list of currently
funded research projects, visit www.californialung.org.
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