 New
discoveries in asthma research
(Right) Professor Neil Pearce
Pioneering research by the University’s
Centre for Public Health Research has debunked the widely-held belief
that most asthma is caused by exposure to allergens such as house
dust mites and cats.
Centre Director Professor Neil Pearce says at most, only about one-half
of asthma cases are caused by allergic inflammation of the airways.
The other half are caused by non-allergic mechanisms.
The collaborative research has been undertaken by Dr Jeroen Douwes
and Professor Pearce at the Centre for Public Health Research, together
with Dr Peter Gibson (John Hunter Hospital, Newcastle, Australia)
and Dr Juha Pekkanen (National Public Health Institute, Kuopio,
Finland)
.
The team re-analysed 22 research papers published internationally
to produce the findings, and the results were published in this
month’s edition of the British Medical Association’s journal
Thorax. The journal also carried its own editorial on the findings,
supporting the study’s conclusions.
“For the past 20 years we’ve been focused on the idea
that allergens cause asthma, so preventing asthma meant reducing
exposure to allergens. We thought that if we fitted plastic covers
to our mattresses, threw out our carpets and gave away the cat,
the problem would be solved,” says Professor Pearce.
“But this latest research shows that although allergen exposure
may cause asthma in some cases, it is not the over-whelming cause
that it’s been hyped up to be. This misguided approach has
meant we have lost valuable time and wasted valuable resources.”
Professor Pearce says the allergic response mechanism was always
thought to be the reason babies became asthmatics in the first place.
The Centre’s findings have now put those beliefs open to question.
“If you’re having a baby, you’re supposed to get
rid of the cat, but quite a few studies have shown that having a
cat early in life actually protects against asthma. Certainly there
is little evidence that exposure to allergens early in life actually
causes asthma, and if it does then it can only account for, at most,
half of the cases.”
Professor Pearce says several ‘myths’ always get repeated
in the asthma debate and none is helpful.
“It is often claimed that we have the highest asthma rates,
with the greatest severity, in the world, but in fact we’re
about the same as the other English-speaking countries.
“We’ve spent 20 years trying to find out what is unique
about New Zealand, when in fact, we should be trying to find out
what we have in common with other English-speaking countries. Why
is it, for example, that cities such as Tucson in the US have virtually
no dust mites at all, yet their asthma rates are the same as ours?”
With New Zealand’s 600,000 asthmatics currently creating an
economic burden of $800 million per annum, the accurate targeting
of both prevention and treatment is fundamental.
“This new research shows that non-allergic mechanisms cause
at least one-half of asthma cases, but we still don’t know
what these mechanisms are because all of the attention has been
focused on allergens. If half of all asthma cases occur through
non-allergic mechanisms, then telling those people to throw out
the carpets and get rid of the cat will be of no benefit at all,”
he says.
“More importantly, if we want to prevent people getting asthma
in the first place, then we need to know what these non-allergic
causes of asthma are.”
The Centre is now focusing much of its Health Research Council funding
into learning more about these non-allergic mechanisms. Collaborative
studies are under way with the Malaghan Institute of Medical Research
to investigate the basic processes involved in non-allergic asthma.
A three-year study has also begun on why children living on farms
are less likely to contract asthma.
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