UA Study Shows Day Care and Older Siblings Protect Children from Asthma
Babies who attended day care and those with older siblings are protected from developing asthma later in life, according to a study by Dr. Thomas M. Ball, assistant professor of clinical pediatrics at the University of Arizona, published in the New England Journal of Medicine today.
"The huge increase in the numbers of children with asthma worldwide, particularly in developed countries, has been well-documented," Ball says. "It's crucial to better understand the biological causes of the current asthma epidemic in order to develop new approaches to asthma prevention."
The researchers studied more than 1,000 children who have been followed from birth as part of the Tucson Children's Respiratory Study. Information has been collected for more than 15 years on the children's health and their environment, which allows researchers to study the relationships between the two. This study looked at two specific variables -- older siblings and participation in day care -- to determine their impact on the development of asthma.
Because most children with asthma also have allergies, the researchers used clinical tests of the child's susceptibility to allergies to determine their likelihood of developing asthma. This information was collected when the children were 6 and 11 years old.
The researchers found that children who attended day care during the first six months of life, or had two or more older siblings, were less allergic at ages 6 and 11, and half as likely to develop asthma later in life than children who did not attend day care or had no older siblings.
The children also were evaluated for frequent wheezing, which is one of the clinical signs of childhood asthma. Although many children wheeze from infections early in life, not all of them go on to develop asthma later in childhood. The researchers found that children who attended day care and who had older siblings wheezed more at 2 and 3 years of age, but less at ages 6 and 13.
"One theory suggests that infections play an important role in the maturation of the immune system, causing the immune system to become less allergic," says Anne L. Wright, UA research professor of pediatrics and senior author of the study. "This study supports the view that infections, or exposure to other children, protect against the development of asthma and allergies."
This research was a collaboration of the Arizona Respiratory Sciences Center and the Steele Memorial Children's Research Center at the University of Arizona Health Sciences Center. Other researchers involved in the study include Dr. Jose A Castro-Rodriquez, Kent A. Griffith, Catharine J. Holberg and Dr. Fernando Martinez. The work is supported by the National Heart, Lung and Blood Institute.
University of Arizona in the News