What is asthma and what we already know


	In asthma the airways (tubes of your lungs) become narrow making it more difficult to breathe in and out.
	People with asthma can also experience: Wheeze Coughing Tightness in the chest
	These symptoms are often worse at night or first thing in the morning


	In the UK around 10% of children (1.5 million) have ongoing asthma.
	Asthma seems to start early in childhood, perhaps very early.
	However quite a lot of wheezing in early life isn't 'asthma' but simply a response to a chest infection (especially in small babies).
	Asthma is more common among boys although this difference disappears during the teens as boys more often grow out of asthma.
	Having a parent (especially a mother) with asthma makes it more likely that a child will develop asthma.
	UK children with asthma are often allergic to house dust mites or cat fur.
	Children with asthma quite often have hayfever or eczema as well.
	There is more asthma now than there used to be.
	This trend probably started about fifty years ago. There's some evidence that the increase is slowing down - or may have stopped altogether.
	Across the world, asthma is most common in Australia, New Zealand and the UK.
	It's less common in southern and eastern Europe.
	Hayfever (and possibly asthma) seems to be less common in children who come from larger families. They may also be less common among children who grow up on farms.


	Essentially we want to know why some children develop asthma while others don't. It seems obvious that there are 'genetic' reasons but these cannot be the whole answer.
	We would like to know whether children who meet more house dust mite or cat allergen early in life are at higher risk of asthma. If this is so then it might be possible to devise ways of reducing such exposures.
	We would like to know whether fumes in the home - such as from cigarettes or even from gas appliances - are important.
	We would like to know whether early infections are important. It has been suggested that children who meet plenty of (minor) infections early in life develop a properly 'balanced' immune system; and that asthma and similar allergies may develop where this balance has not been achieved. This may explain why children from larger families and children who grow up on farms seem to be protected. This theory is often called the 'hygiene hypothesis'.

UK research supported by The Colt Foundation