TORONTO - Children whose mothers suffer prolonged depression or anxiety appear to have a higher rate of asthma than other youngsters, independent of other risk factors for the increasingly common respiratory condition, a Canadian study suggests.

The study, which analyzed seven years of health records for almost 14,000 Manitoba children born in 1995, found that kids whose mothers were chronically distressed during those childhood years had a 25 per cent increased risk of developing asthma.

The finding, reported in the American Journal of Respiratory and Critical Care Medicine, was independent of other factors associated with childhood asthma, such as genetic predisposition, household income, being male or female, or living in an urban or rural environment.

Lead investigator Dr. Anita Kozyrskyj, an associate professor of pharmacy at the University of Manitoba, said she and her colleagues determined through the health records whether children had asthma by age seven and related it to maternal distress as defined by doctor visits, hospitalizations and prescriptions for depression and anxiety.

Maternal distress was categorized by onset and duration into four categories: no distress, postpartum distress, short-term distress and long-term distress.
 

"And it's those mothers in the long-term or persistent category who had the greatest number of health-care visits and prescription medications," Kozyrskyj said Tuesday from Winnipeg. "So that may be an indication of more severe depression and/or anxiety."

Even taking other major risk factors for childhood asthma into account, she said, "the persistent maternal distress measure still is significantly associated with the development of asthma at age seven."

But she stressed that mothers should not take the findings to mean that they are to blame for their children's asthma.

"I think the significance of the results is that there is an association," she said, noting that the study design cannot determine direct cause.

"We know that genetics, a maternal history of asthma, maternal smoking are also very important risk factors for the development of asthma. So this is another risk factor."

At this point, scientists don't know how maternal distress might contribute to a child becoming asthmatic.

But Kozyrskyj said depressed or anxious mothers are more likely to indulge in behaviours that are known to contribute to asthma in youngsters, such as using tobacco that creates second-hand smoke.

"Aside from that ... depressed mothers are less likely to interact with their infants," she said, noting that studies of laboratory rats show that pups with inattentive mothers have abnormal immune and stress responses. The same may be true for humans, she added.

Kozyrskyj said too many mothers, particularly in low-income families, are raising children in environments that contribute to chronic distress.

"Some moms live in environments with low social support and high family conflict or violence, so environment leads to the depression or the anxiety," she said. "So it hardly could be mother's fault when mother is responding to a very stressful environment."

Public health programs that help mothers deal with depression and anxiety - and families with conflict and other issues - may need to be beefed up and expanded, she said.

"So if you can prevent (maternal distress), therefore you decrease your likelihood of asthma and other childhood conditions, too."


Source : Canadian Press