What Is Asthma?
Asthma is a chronic lung disease that inflames and narrows
the airways. Asthma causes recurring periods of wheezing (a whistling sound
when you breathe), chest tightness, shortness of breath, and coughing. The
coughing often occurs at night or early in the morning.
Asthma affects people of all ages, but it most often starts
during childhood. In the United States, more than 25 million people are known
to have asthma. About 7 million of these people are children.
To understand asthma, it helps to know how the airways work.
The airways are tubes that carry air into and out of your lungs. People who
have asthma have inflamed airways. This makes them swollen and very sensitive.
They tend to react strongly to certain inhaled substances.
When the airways react, the muscles around them tighten.
This narrows the airways, causing less air to flow into the lungs. The swelling
also can worsen, making the airways even narrower. Cells in the airways might
make more mucus than usual. Mucus is a sticky, thick liquid that can further narrow
the airways.
This chain reaction can result in asthma symptoms. Symptoms
can happen each time the airways are inflamed.
Sometimes asthma symptoms are mild and go away on their own
or after minimal treatment with asthma medicine. Other times, symptoms continue
to get worse. When symptoms get more intense and/or more symptoms occur,
you're having an asthma attack. Asthma attacks also are called flareups or exacerbations.
Asthma Causes and Triggers
No one really knows what causes asthma. What we do know is
that asthma is a chronic inflammatory disease of the airways. The causes of
asthma symptoms can vary for different people. Still, one thing is consistent
with asthma: when airways come into contact with an asthma trigger, the airways
become inflamed, narrow, and fill with mucus.
Allergies
Almost all asthma sufferers have allergies. In fact, over
25% of people who have hay fever (allergic rhinitis) also develop asthma.
Allergic reactions triggered by antibodies in the blood often lead to the
airway inflammation that is associated with asthma.
Common sources of indoor allergens include animal proteins
(mostly cat and dog allergens), dust mites, cockroaches, and fungi. It is
possible that the push towards energy-efficient homes has increased exposure to
these causes of asthma.
Medications
Many people with asthma have aspirin-sensitive asthma and
it's possible they're sensitive to other medications such as
anti-inflammatory drugs like ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn),
aspirin, and beta-blockers (used to treat heart disease, high blood pressure,
and glaucoma). If you know you're sensitive to these drugs, make sure your
doctor has the problem documented on your chart, and always talk to your
pharmacist about this reaction before taking a new medication.
Environmental
Factors
Allergic reactions and asthma symptoms are often the result
of indoor air pollution from mold or noxious fumes from household cleaners and
paints. Other indoor environmental factors associated with asthma include
nitrogen oxide from gas stoves. In fact, people who cook with gas are more
likely to have symptoms such as wheezing, breathlessness, asthma attacks, and
hay fever.
Pollution, sulfur dioxide, nitrogen oxide, ozone, cold
temperatures, and high humidity have all been shown to trigger asthma in some
individuals.
During periods of heavy air pollution, there tend to be
increases in asthma symptoms and hospital admissions. Smoggy conditions release
the destructive ingredient known as ozone, causing coughing, shortness of
breath, and even chest pain. These same conditions emit sulfur dioxide, which
also results in asthma attacks by constricting airways.
Weather changes have also been known to stimulate asthma
attacks. Cold air can lead to airway congestion, bronchoconstriction (airways
constriction), secretions, and decreased mucociliary clearance (another type of
airway inefficiency). In some populations, humidity causes breathing
difficulties as well.
Obesity
Overweight adults - those with a body mass index (BMI)
between 25 and 30 - are 38% more likely to have asthma compared to adults who
are not overweight. Obese adults - those with a BMI of 30 or greater - have
twice the risk of asthma. According to some researchers, the risk may be
greater for non-allergic asthma than allergic asthma.
Pregnancy
The way you enter the world seems to impact your
susceptibility to asthma. Babies born by Caesarean sections have a 20% increase
in asthma prevalence compared to babies born by vaginal birth. It is possible
that immune system-modifying infections from bacterial exposure during Cesarean
sections are responsible for this difference.
When mothers smoke during pregnancy, their children have
lower pulmonary function. This may pose additional asthma risks. Research has
also shown that premature birth is a risk factor for developing asthma.
Stress
People who undergo stress have higher asthma rates. Part of
this may be explained by increases in asthma-related behaviors such as smoking
that are encouraged by stress. However, recent research has suggested that the
immune system is modified by stress as well.
Exercises
Strenuous exercise can cause a narrowing of the airways in
about 80% of people with asthma. In some people, exercise is the main trigger
for their asthma symptoms. If you have exercise-induced asthma, you will feel
chest tightness, coughing, and difficulty breathing within the first five to
eight minutes of an aerobic workout. These symptoms usually subside in the next
20 to 30 minutes of exercise, but up to 50% of those with exercise-induced
asthma may have another asthma attack six to 10 hours later. It is important to
warm up slowly and adequately prior to rigorous exercise. This may prevent an
attack.
Genes
It is possible that some 100 genes are linked to asthma - 25
of which have been associated with separate populations as of 2005.
Genes linked to asthma also play roles in managing the
immune system and inflammation. There have not, however, been consistent
results from genetic studies across populations - so further investigations are
required to figure out the complex interactions that cause asthma.
Mom and Dad may be partially to blame for asthma, since
three-fifths of all asthma cases are hereditary. The Centers for Disease
Control (USA) say that having a parent with asthma increases a person's risk by
three to six times.
Genetics may also be interacting with environmental factors.
For example, exposure to the bacterial product endotoxin and having the genetic
trait CD14 (single nucleotide polymorphism (SNP) C-159T) have remained a well-replicated
example of a gene-environment interaction that is associated with asthma.
Sinusitis and Other
Upper Respiratory Infections
Much like asthma causes inflammation in the lining of the
airways, sinusitis causes inflammation in the mucous membranes that line the
sinuses. This inflammation causes the mucous membranes in the sinuses to
secrete more mucus -- also similar to asthma. When the sinuses get inflamed,
the airways respond similarly in many people with asthma, leading to sinusitis
with asthma. Prevention and prompt treatment of a sinus infection is often
necessary to help relieve asthma symptoms.
Airway
Hyperreactivity
Researchers are not sure why airway hyperreactivity is
another risk factor for asthma, but allergens or cold air may trigger
hyperreactive airways to become inflamed. Some people do not develop asthma
from airway hyperreactivity, but hyperreactivity still appears to increase the
risk of asthma.
Atopy
Atopy - such as eczema (atopic dermatitis), allergic
rhinitis (hay fever), allergic conjunctivitis (an eye condition) - is a general
class of allergic hypersensitivity that affects different parts of the body
that do not come in contact with allergens. Atopy is a risk factor for
developing asthma.
Some 40% to 50% of children with atopic dermatitis also
develop asthma, and it is probable that children with atopic dermatitis have
more severe and persistent asthma as adults.
Smoking as Risk
Factor for Asthma
The well-established approach to the connection between
tobacco smoking and asthma is very conservative. Smoking (first-hand or
second-hand) is a substantial risk factor for asthma development. Most public
resources support this point of view: that smoke from cigars, cigarettes, and
pipes is a powerful trigger for asthma symptoms.
The mechanism of action is defined as following. When a
person inhales tobacco smoke, irritating substances settle in the moist lining
of the airways. These substances can cause an attack in a person who has
asthma. In addition, tobacco smoke damages tiny hair-like structures in the
airways called cilia. Normally, cilia sweep dust and mucus out of the airways.
Tobacco smoke damages cilia so they are unable to work, allowing dust and mucus
to accumulate in the airways. Smoke also causes the lungs to make more mucus
than normal. As a result, even more mucus can build up in the airways,
triggering an attack.
As to the second-hand smoking, adults and children who live
with a smoker are more likely to develop respiratory illnesses. Children are
especially at risk because their lungs are smaller and still developing. Exposure
to second-hand smoke can lead to decreased lung function and symptoms of airway
inflammation such as cough, wheeze, and increased mucus production, especially
in children. Children with asthma are especially sensitive to second-hand
smoke. They are more likely to develop asthma symptoms when exposed to
second-hand smoke. They are also more likely to develop lung and sinus
infections. These infections can make asthma symptoms worse and more difficult
to control.
The problem is that the results of the related studies are
surprisingly mixed, offering a strong positive correlation of up to 30% asthma
development risk increase for smokers in one study and substantial negative
correlation results in another. For example, one study in Finland revealed the
fact that asthma risk increased with number of cigarettes smoked per day up to
14 but was significantly lower in those who smoked 15 or more cigarettes per
day. The same trend held true for cigarette years, with asthma risk being
higher in the 1-to-199 cigarette years category, and lower in the over 200
category. Another interesting discovery was that for ex-smokers the risk to
develop asthma is higher than for active smokers.
Here are some other results obtained from the studies:
- From the National Jewish Medical and Research Center comes a 2012 report that the heavier pollution during the winter months does not worsen asthma. A three year study focusing on minority children in urban areas found that respiratory infections, such as colds, rather than particulate matter, such as found in secondhand smoke, is responsible for triggering asthma attacks. The press release ends with some common sense advice for parents to not worry about air pollution but pay closer attention to "preventing and treating the real wintertime threat to their children's health - colds and other respiratory infections."
- Based on Government Environment Protection Agency (EPA) report, the number of children whose blood levels showed effects from second hand smoke declined by about one-fifth to one-half between 1988 and 2000, depending on their levels of exposure. Those figures are obtained by tracking the amount of cotinine, a breakdown product of nicotine in blood. But the report also found that the percentage of children getting asthma has doubled in two decades, rising from 3.6 percent in 1980 to 8.7 percent, or 6.3 million children by 2001. These results distortion is not in EPA interests, since this organization was trying to reach an opposite conclusion. It is obvious that there are other risk factors for asthma development, much stronger than tobacco smoking.
- There is one more research, performed in California, which showed the similar trends. The percentage of Californians who have been diagnosed with asthma at some point in their lives is significantly higher than the national average, while California has the second lowest rate of smoking in the nation. The San Francisco Bay Area, the most health obsessed region in the state has higher rates of asthma than the rest of the state. One of the researchers suggested that the asthma cases are indeed triggered by environment, but with a completely negative connotation. "Our clean living ways perhaps might be leading to this global rise in asthma and allergies. Most people assume asthma results from air pollution or other dirt in the environment. But it may be caused by just the opposite. The latest research shows the cleaner the environment, the more cases of asthma. It has to do with our immune systems”.
There have been other studies that suggest that our
hyper-consciousness of "health" and our attempt to raise children in
an antiseptic environment contribute to weak immune systems. May be, it
is time to reverse our cleanness-conscious attitude, and make a step back to
the Mother Nature?
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