What Causes Asthma?
The exact cause of asthma isn't known.
Researchers think a combination of factors (family genes and certain
environmental exposures) interact to cause asthma to develop, most often early
in life. These factors include:
- An inherited tendency to develop allergies,
called atopy (AT-o-pe)
- Parents who have asthma
- Certain respiratory infections during
childhood
- Contact with some airborne allergens or exposure
to some viral infections in infancy or in early childhood when the immune
system is developing
If asthma or atopy runs in your family, exposure to
airborne allergens (for example, house dust mites, cockroaches, and possibly
cat or dog dander) and irritants (for example, tobacco smoke) may make your
airways more reactive to substances in the air you breathe.
Different factors may be more likely to cause asthma
in some people than in others. Researchers continue to explore what causes
asthma.
The "Hygiene Hypothesis"
One theory researchers have for what causes asthma
is the "hygiene hypothesis." They believe that our Western lifestylewith
its emphasis on hygiene and sanitationhas resulted in changes in our
living conditions and an overall decline in infections in early childhood.
Many young children no longer experience the same
types of environmental exposures and infections as children did in the past.
This affects the way that the immune systems in today's young children
develop during very early childhood, and it may increase their risk for atopy
and asthma. This is especially true for children who have close family members
with one or both of these conditions. |