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AsthmaToday asthma is viewed as a chronic (long-lasting) inflammatory disease of the airways. In those susceptible to asthma, this inflammation causes the airways to narrow periodically. This, in turn, produces wheezing and breathlessness, sometimes to the point where the patient gasps for air. Obstruction to air flow either stops spontaneously or responds to a wide range of treatments, but continuing inflammation makes the airways hyper-responsive to stimuli such as cold air, exercise, dust mites, pollutants in the air, and even stress and anxiety. Between 1982-92, the numbers of those with asthma rose by 42%. Not only is asthma becoming more frequent, but it also is a more severe disease than before, despite modern drug treatments. The changes that take place in the lungs of asthmatic persons makes the airways (the bronchi and the smaller bronchioles) hyper-reactive to many different types of stimuli which do not affect healthy lungs. In an asthma attack, the muscle tissue in the walls of the bronchi go into spasm and the cells lining the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi to become narrowed (bronchoconstriction). As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it. Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscle to contract and to stimulate mucus formation. These substances, which include histamine and a group of chemicals called leukotrienes, also bring white blood cells into the area, which is a key part of the inflammatory response. Many patients with asthma are prone to react to such "foreign" substances as pollen, house dust mites or animal dander; these are called allergens. On the other hand, asthma affects many patients who are not "allergic" in this way. Asthma usually begins in childhood or adolescence, but it also may first appear during adult years. While the symptoms may be similar, certain important aspects of asthma are different in children and adults. Child-Onset Asthma When asthma does begin in childhood, it often does so in a child who is likely, for genetic reasons, to become sensitised to common "allergens" in the environment (an atopic person). When these children are exposed to house-dust mites, animal proteins, fungi or other potential allergens they produce a type of antibody that is intended to engulf and destroy the foreign material. This has the effect of making the airway cells sensitive to particular materials. Further exposure can lead rapidly to an asthmatic response. This condition of atopy is present in at least one-third and as many as half of the general population. When an infant or young child wheezes during viral infections, the presence of allergy (in the child itself or in a close relative) is a clue that asthma may well continue throughout childhood. Adult-Onset Asthma Allergenic materials may also play a role when adults become asthmatic. Asthma can start at any age and in a wide variety of situations. Many adults who are not allergic do have such conditions as sinusitis or nasal polyps, or they may be sensitive to aspirin and related drugs. Another major source of adult asthma is exposure at work to animal products, certain forms of plastic, wood dust, or metals. Research has shown that people who ate the most fruit and vegetables have the healthiest lung function. Vitamins C and E are believed to help reduce the severity of the inflammatory response in the lungs of people with asthma. A diet that includes a high level of nutrients can also boost the immune system and help ward off colds and flu, both of which are common asthma-triggers. | |||
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