Asthma as defined by the National Institutes of Health is an inflammatory disorder of the lungs and airways. The inflammation can lead to attacks of wheezing, shortness of breath, tightness in the chest and coughing.
Allergens
Around 30 percent of all adult asthma cases are caused or triggered by certain allergens, according to the Allergy and Asthma Foundation of America (AAFA). These allergies may have been present since childhood and are now in adulthood triggering a strong enough immune response to involve the lungs, or these allergies can develop as a response to repeated exposure. Common allergens include animal dander, dust, chemicals in the air, pollen and mold. The reaction to these allergens can be an asthma attack with wheezing, but most commonly a dry cough is the most persistent symptom of adult asthma.
Genetics and Ethnicity
There is still not enough known about genetics specifically to know what causes asthma, but there is a belief that if it runs in the family, it is likely the cause of adult onset asthma. Also being born female puts someone at a greater risk for developing asthma as an adult. The University of Maryland's Medical Center states that after adolescence women are more likely to report more severe symptoms of asthma than are men. Additionally, African Americans as a group more commonly report asthma than do Caucasians or other ethnic groups. It is unknown if socioeconomic conditions contribute to this or if it is based on genetics alone.
Infections
The AAFA reports that many Americans do not report their first asthma attack or symptoms until after a long-term cold, flu, bronchitis or pneumonia infection. Since all of these illnesses infect the respiratory tract, leftover inflammation from the immune response to the germs or viruses could be responsible for the asthma.
Hormones
Hormones can cause asthma to develop, although the reason for this is not understood. The AAFA states that most women do not report their first episode of asthma symptoms until their first pregnancy. The asthma develops during the pregnancy or just after. The University of Maryland states that women with adult asthma report a 30 to 40 percent variance in severity of symptoms around the time of their menstruation.
Obesity
Extra weight around the chest and trunk causes the muscles of the respiratory system to work harder to breath. Anything that compromises the airway can lead to problems like asthma. The University of Maryland's Medical Center does not have enough information to say that there is a direct causal relationship between obesity and asthma, but there is a strong association between obesity and asthma. The symptoms are usually more severe and are combined with more difficulty with shortness of breath rather than just a dry cough. Additionally, it has been shown that weight loss is correlated with increased lung function.
