Asthma - A Short Introduction

What is asthma? If you can answer this question to everyone's satisfaction, you just may get a Nobel Prize. The most common definition considers asthma a chronic inflammatory disorder characterized by episodes of reversible bronchospasm, commonly known as an asthma attack. If you pick up a standard medical dictionary and look up the word "asthma," you'll probably read something like this: "Asthma is a chronic inflammatory disease of the airways that is characterized by increased responsiveness of the tracheobronchial tree to a multiplicity of stimuli."

 

In less technical jargon, asthma is a medical condition that affects the lung's airways, causing them to become smaller and thereby blocking airflow. This airway obstruction is reversible, meaning the blockage eventually goes away, either by itself or through the use of medication. Doctors call this airway constriction "bronchospasm" or "bronchocon-striction." What causes this reversible bronchoconstriction varies from person to person and can range from allergies to exercise to emotions. Central to bronchospasm is a chronic inflammation of the airways that makes them more sensitive and more likely to constrict under the right circumstances. Why asthmatics have this chronic inflammation and why asthma varies from person to person are questions subject to intense controversy. Still confused? So are a lot of scientists and physicians. Perhaps the best way to view asthma is to consider it as several different problems rolled into one, with environmental, allergic, genetic, emotional, infectious, and nutritional factors, along with immune dysfunction, each playing a role.

 

"Why do I have asthma?" The answer to this question varies from person to person. We do know that virtually every asthmatic has hyperreactive airways, but the real question is "Why?" There is an emerging consensus that asthma results from a complex interplay between genes and environment, that people who have inherited particular genes will develop asthma if exposed to the proper environment. Genetic analysis has made it increasingly clear that many genes are responsible for asthma. We presently can't control our genetic heritage, but as gene therapy matures we may one day be able to genetically treat asthma along with many other medical disorders, from diabetes to cancer.

 

Though we can't control our genes, we can control our environment. Environment has become increasingly recognized as a major contributor to asthma. Many people can have their asthma "cured" if they can identify and remove the appropriate environmental triggers. This is supported by numerous studies that place responsibility for the current asthma epidemic on our urbanized, Western culture. Population studies have found that asthma is primarily a problem of affluent, industrialized societies. In fact, asthma is rare in many of the world's poorest countries. One study, published in The Lancet, examined the incidence of asthma in Ethiopia and found that urban children were three times more likely to have asthma than rural children, an effect the authors attributed to "general changes in the domestic environment." Another study found that the incidence of asthma in urban South Africa was 3.17 percent compared to only 0.14 percent in a rural area.

 

What is responsible for this geographic variation is the million-dollar question. As you can imagine, when you get a group of physicians and scientists in the same room to discuss the causes of asthma, you get some lively controversy. The general consensus is that the asthma epidemic results from a combination of dietary and environmental factors, most notably oxidant stress.