Therapy Analysis - Asthma
Harder to breathe: living with asthma
For the millions of people who are unfortunate enough to suffer from the chronic lung disease asthma, struggling to breathe is something of a regular - even daily - experience.
Sufferers airways are hypersensitive to one or more of a variety of triggers - specific stimuli such as respiratory infections, allergens, irritants, exercise and even emotional stress. Exposure to a trigger causes acute episodes of wheezing, chest tightness, coughing and shortness of breath leading to airway obstruction and inflammation. In order to avoid falling prey to a potentially life-threatening asthma attack, many asthmatics keep detailed records of both the timing and nature of them, so that potential culprits, such as washing powders, cats, air purifiers or air conditioning can be identified and avoided.
A disease commonly associated with affluence, asthma is far more widespread in developed countries, and although it occurs more frequently in children, it can affect people of any age. Current figures stand at more than 100 million sufferers worldwide, with a US prevalence of 6.4%, but most alarmingly, its prevalence, like that of allergic diseases in general, has risen dramatically in the past decade alone, a western trend that seems set to continue. In Britain, one of the developed countries with the worst allergy epidemics, it went up from 18.4% to 20.9% between 1991 and 2003.
There are two types of asthma. Allergic or extrinsic asthmatics, known as 'atopic' asthmatics, are prone to becoming over-sensitized to allergens such as pollen or dust, resulting in an allergic reaction involving the smooth muscle cells of the airways. People with this form of asthma usually have co-existing allergies. Nonatopic or intrinsic asthma encompasses all other triggers, including stress and exercise, and often shows no family history. During the initial 'immediate phase' of an asthma attack, the overactivity of the immune system to a trigger leads to swelling of the airways, which is usually the extent of the attack in non-atopic asthmatics. In allergic asthma however, the initial allergen exposure stimulates a chain reaction of immune-cell recruitment, which can occur up to 8 hours later and results in further inflammation...while most agree on the involvement of a hereditary component, several theories have been aired in recent years, including implications of diet, pollution and viral infections.. It can even culminate in Status Asthmaticus, a frightening and potentially fatal state characterized by severe bronchospasm, which sometimes remains unresponsive to emergency bronchodilator treatment. Over time, repeated asthma attacks can lead to irreversible pulmonary remodelling, causing permanent obstruction in extreme cases.
The causes of asthma are fiercely debated by scientists, and while most agree on the involvement of a hereditary component, several theories have been aired in recent years, including implications of diet, pollution and viral infections. The 'hygiene hypothesis', the theory that early exposure to the dirt-containing microorganisms that the modern world tries obsessively to eradicate, is necessary to 'prime' the immune system, has also gained credibility. Genetically, mutations in genes for the cytokines IL-4, IL-5 and the beta-2 adrenergic receptor (B2AR) are believed to have some involvement and may explain some patients' susceptibility to asthma.
