A study of children with asthma conducted by the University's Woolcock Institute of Medical Research and the Children's Hospital at Westmead has found that the age of the children's parents is a key factor in the early diagnosis of the disease.
The Childhood Asthma Prevention Study (CAPS), involving nearly 600 Australian children up to the age of three, found that those with younger parents were significantly more likely to be diagnosed with asthma at an earlier age.
Almost one in six Australian children has asthma, and the study as it continues is expected to provide valuable information about predicting and treating the disease.
One of the CAPS investigators, Dr Guy Marks, head of Epidemiology at the Woolcock Institute of Medical Research, says there are currently three hypotheses to explain the onset of asthma in children
– and none of them are clearly established as definitive explanations.
"Allergen exposure is possibly the longest standing hypothesis," he said. "The second hypothesis is that there's some component of diet, particularly the composition of fatty acids and the presence of anti-oxidants in the diet."
Components of both of these hypotheses are being tested in CAPS study.
The third hypothesis, which is not being directly tested in this study, is the so-called "hygiene" hypothesis which suggests that exposure to certain microbes in early life might actually protect against the development of allergic disease.
The children in the Woolcock study came from western and south-western Sydney and were tracked from birth in the first three years of their life between 1997 and 2000.
The study found the two interventions – house dust mite avoidance and diet – had no effect on the timing of the first diagnosis of asthma
in the first three years of life.
But for every one year increase in the age of the parents, the age of the first diagnosis of asthma in the child was later.
Dr Marks said it was still too early to speculate on the reasons for the findings, but suggested that one possible explanation was that younger parents might be more likely to take their child to the doctor and have the disease detected earlier.
Another possible explanation was that first-born children have a higher risk of developing allergic disease than children born into a family with older siblings.
"As older parents are more likely to have previous children than younger parents, this may be the basis for the protection against asthma," Dr Marks said.
Dr Marks says asthma cannot be reliably diagnosed in early life, so results from the next phase of the study – when the study cohort reaches the age of five – will provide more data in predicting and treating the disease which is present in up to 16 percent of Australian children.