Research Profile - Year One
Dr. Allan Becker
A study that tracked hundreds of children from the womb to their seventh birthday showed a 'multifaceted intervention' in the first year helped prevent asthma.
Conducting cohort studies – monitoring a segment of the population over many years – is a health research investment that keeps delivering dividends.
Consider the work that the University of Manitoba's Dr. Allan Becker originally began 15 years ago, following the progress of about 500 Winnipeg and Vancouver children from the last three months of their mothers' pregnancies until the kids turned seven.
At a Glance
Who – Dr. Allan Becker, Professor and Head, Section of Allergy & Clinical Immunology, Department of Pediatrics and Child Health, University of Manitoba
Issue – Asthma begins in childhood and is often associated with allergic reactions to environmental stimuli. Is it possible to prevent the onset of asthma by limiting exposure to allergens?
Approach – Dr. Becker led a study that tracked the health of a group of children who were breastfed and had less exposure to allergens during the first year of life. The group showed a reduction of almost 60% in the prevalence of asthma at age seven compared to the control group.
Impact – The study demonstrated that the first year of life is a critical window of opportunity for protecting children from developing asthma.
The Next Step – Dr. Becker is beginning a new study to see if the decrease in asthma prevalence remained significant during the teen years – when girls have a higher risk for getting the disease.
In that study – undertaken before the Canadian Institutes of Health Research (CIHR) existed – one group of children underwent a "multifaceted intervention" for the first year of life in which they were breastfed and, as much as possible, kept from exposure to allergy triggers such as dust mites, animal dander and tobacco smoke. The results were remarkable.
"At seven years there was almost a 60% decrease in the likelihood of asthma in the children in the intervention group," says Dr. Becker. "And this occurred in the absence of any difference in the likelihood of these children being allergic, which is often a precursor to developing asthma, or the likelihood of the children having physiological underpinnings for asthma."
The findings from the Canadian Childhood Asthma Primary Prevention Study were published in a 2005 report in the Journal of Allergy and Clinical Immunology – one of more than two dozen publications produced so far from the cohort study.
While Dr. Becker isn't sure "what it was among the interventions that actually had the impact," his cohort study showed that the first year of life represents an important window of opportunity to protect children from developing asthma. "There clearly is something critical about that first year of life."
Next up, Dr. Becker will check back with the children – who are now teenagers.
"With our current CIHR grant we have a phenomenal opportunity to reassess these children in terms of their immune status, their physiological status, and their clinical status for allergy and asthma to see whether our intervention in early life continued to modify the life trajectory risk for asthma."
He believes that there may be a second window of opportunity during the teen years – and that girls may be the main beneficiaries of interventions taken during that time.
"We know from other studies that there is a gender shift in asthma prevalence: being male is a major risk factor for asthma right through the early school years. By puberty, that levels out. From the teenage years onward, being female is more of a risk factor – with a 20-25% risk for asthma among girls and a threefold increased risk among females for severe asthma as they enter the young adult years."
By assessing how the children fared as they became teenagers, Dr. Becker hopes to get a better understanding of what happens "in the preteen years where that shift begins to appear and boys tend to lose asthma while girls begin to develop it at a higher incidence."
Dr. Becker is also a Principal Investigator in the Canadian Healthy Infant Longitudinal Development Study, which is funded by CIHR and the Allergy, Genes and Environment Network of Centres of Excellence. It will track a cohort of 5,000 children in Vancouver, Edmonton, Winnipeg and Toronto from birth through age five to examine the impact of environmental factors on kids' health.
"Studies like this are absolutely critical if we're going to understand the origins of diseases like asthma," says Dr. Becker. "When we began our prevention study in the early 1990s, we thought we knew everything that we needed to do to help prevent children from developing this disease. We need to understand the environment way more broadly. We need to understand a whole lot more."
"It's been known for decades that if you're sensitized to the common allergens – such as dust mites, cats, dogs, and out-of-door mould called Alternaria – that you have a substantially greater risk of developing asthma. That linkage is very strong, such that 75% of children with asthma are allergic to those common allergens. Our whole thesis was that by decreasing exposure, we would be able to prevent sensitization and prevent development of asthma."
-- Dr. Allan Becker