As discussed by the National Institutes of Health (NIH), asthma is a chronic lung disease that results in inflammation and narrowing of the airways. This disease often starts in childhood, but affects people of all ages. Asthma causes symptoms such as wheezing, chest tightness, difficulty breathing and coughing. It is a frequent cause of hospitalization during childhood and results in missed days of school and work for children and adults.
Pathophysiology
Patients with asthma have airways, or tubes that carry air in and out of the lungs, which are more inflamed than usual. These airways are very sensitive and become more inflamed in response to certain substances that are inhaled. When the airways react to a substance, the muscles around the airway tighten and make it more difficult for air to reach the lungs and for the patient to exhale air out of the lungs. The cells that line the lungs also make more mucus, which further narrows the airways. Many patients experience minimal symptoms from their inflamed airways, but can experience "attacks" of asthma in response to an inhaled substance
Risk Factors
As discussed by the NIH, the exact cause of asthma is not known. However, several factors are known to increase the risk of developing asthma. Patients with a tendency to develop allergies, otherwise known as atopy, have a higher risk of developing asthma. Patients with parents who have asthma and who were exposed to certain viruses during infancy and early childhood may also have an increased risk.
Environmental Triggers
Environmental triggers are substances that, when inhaled, trigger an asthma attack in a susceptible patient. Triggers are different for each patient with asthma. As discussed by the Centers for Disease Control and Prevention (CDC), some of the most frequent environmental triggers include tobacco smoke, dust mites, air pollution, cockroach allergens, pets such as dogs and cats, and mold. It is important to identify an individual patient's environmental triggers because often the environment can be modified to reduce the patient's risk of exposure.
Other Triggers
While most patients with asthma have attacks related to exposure to environmental triggers, some patients have asthma that is triggered by other stimuli. Strenuous physical activity can trigger attacks in some patients, particularly in the setting of high humidity. Weather changes and extreme weather such as freezing temperatures or thunderstorms can trigger asthma in other patients. Illness is a frequent asthma trigger, and some patients are susceptible to asthma attacks related to emotional states.
Theories/Speculation
One theory regarding the development of asthma is known as the "hygiene hypothesis." As an emphasis on hygiene and sanitation has become prevalent in society, patients are no longer exposed to the same allergens and germs. This lack of exposure may change the way that the immune system develops in infancy and early childhood and increase the risk of developing asthma.
