The different types of asthma
Asthma, a disease with many variations
Asthma is a chronic inflammatory disease of the airways, whose symptoms have very different manifestations from one individual to another. While someone with only mild symptoms can usually cope with everyday life without major problems, a more pronounced course of the disease giving rise to shortness of breath and recurring asthma attacks will severely restrict the lives of those afflicted. Even when the symptoms are kept at bay, severe asthma sufferers live in constant fear of a renewed attack.
In order to know what makes the symptoms worse or what can trigger an asthma attack, everyone should know what type of asthma they have. This will help them to avoid the triggers or situations that might provoke asthma attacks.
What types of asthma are there?
Why people get asthma is not yet fully understood. An inherited component and/or environmental factors contribute to the development of asthma. Basically, three types of asthma are distinguished depending on the trigger:
allergic asthma, also called extrinsic asthma
non-allergic asthma, also called intrinsic asthma
If children suffer from asthma, it is usually caused by an allergy. With adults, on the other hand, in 30 to 50 percent of cases the disease is not triggered by an allergy. Adults often have a mixed form of allergic and non-allergic asthma.
Allergic (extrinsic) asthma
Allergic asthma is an allergic reaction of the body to inherently harmless substances such as pollen, animal hair, certain foodstuffs, or house dust. Allergic asthma is the most widespread form of asthma. Over eight million people in Germany suffer from it, with it affecting significantly more children than adults. Allergic asthma is one of the most common chronic diseases in childhood.
The body's own immune system perceives inherently harmless substances (allergens) in the environment as a threat, causing it to go into overdrive and potentially trigger an asthma attack. This leads to inflammation of the lower respiratory tract, which in turn leads to increased production of mucus and narrowing of the airways. This inflammatory process is called type 2 inflammation, which is characterized by typical inflammatory cells and inflammatory mediators (endogenous substances that cause an inflammatory reaction). Asthma characterized by type 2 inflammation can be detected by specific biomarkers. In addition to immunoglobulin E (IgE antibodies) and eosinophils (special white blood cells that contribute to immune defense), these include FeNO (fractional exhaled nitric oxide).
When asthma is triggered by a pollen allergy, it is also called seasonal asthma. Triggers are certain pollen or house dust mites that are inhaled. Outside the pollen season, seasonal asthmatics do not experience any symptoms. However, the Federal Association of Pulmonologists (BdP) warns against interrupting treatment completely outside the pollen season. Why? Because the inflammation in the bronchial tubes doesn’t go away – even if you’re not experiencing any symptoms. These untreated inflammations can cause long-term damage to the lungs of seasonal asthmatics and lead to chronic asthma. Pulmonologists therefore recommend continuing with anti-inflammatory medication outside the pollen season, or rather during the outwardly symptom-free period. Measuring the FeNO value makes it possible to determine the degree of inflammation in the bronchial tubes – regardless of whether symptoms such as shortness of breath are present. This allows doctors to adjust the medication to the actual condition of the bronchial tubes and better control the inflammatory process even during the symptom-free period.
People in certain occupational groups have a significantly higher risk of developing asthma. However, it may be months or even years before the first symptoms appear. These groups include lacquer workers, painters, carpenters, laboratory technicians, veterinarians, and hairdressers. Baker’s asthma triggered by a flour dust allergy is another example.
The onset of asthma results from a permanent over-irritation of the respiratory tract caused by substances present in the environment, leading to hypersensitivity (hyperreactivity). With occupational asthma, certain allergens are not always the root cause or trigger behind the disease, however. Inhaling toxic gases and steams, for example, can also lead to acute damage to the bronchial tubes, resulting in occupational asthma. Significantly, symptoms are much more severe at the workplace than, for example, at weekends or when on vacation.
Non-allergic (intrinsic) asthma
In non-allergic asthma, it is not allergens that trigger the asthma, but rather unspecific stimuli. These include certain medications such as painkillers, solvents, or cold air, stress or infections of the respiratory tract. Physical exertion can also potentially trigger an asthma attack. This is called exercise-induced asthma.
The reason for this is that the airways of asthmatics are chronically inflamed and the inflamed tissue reacts much more hypersensitively to stimuli than in healthy people. It is therefore important to keep the chronic inflammation as the cause of the symptoms in check with long-term drug treatment and to monitor the course of the inflammation closely. An asthma attack triggered by severe stress conditions or exertion is usually the result of hyperventilation. Rapid, heavier breathing irritates the airways over and above normal breathing. Resulting shortness of breath further increases anxiety and stress levels. This sets in motion a vicious circle that can lead to a dangerous narrowing of the airways.
A typical indication of non-allergic asthma is sinusitis. From the outset, non-allergic asthma generally has a more severe course than allergic asthma.
Eosinophilic asthma – a severe form of asthma
The various types of asthma can usually be controlled well with the currently prescribed drugs. There are, however, severe forms of non-allergic asthma that occur only in the second half of life and that do not, or only insufficiently, respond to current drug therapies. In these cases, doctors speak of eosinophilic asthma. This type of asthma is treated with special drugs that suppress inflammatory processes in the lungs.
The term “eosinophilic asthma” is derived from what are known as eosinophilic granulocytes. These are a subgroup of white blood cells that play an important role in immune defense. These defense cells play a significant role in overreactions of the immune system. If the body produces an excessive number of them, they can cause inflammation in the lungs. These inflammations can then in turn lead to asthma attacks.
Doctors can determine whether a patient is suffering from eosinophilic asthma by means of a simple blood test. Like allergic asthma, eosinophilic asthma is a type 2 inflammatory disease and can be detected by the typical biomarkers. An elevated number of eosinophils in the blood, accompanied by a high FeNO level, may indicate eosinophilic asthma.
Often there are mixed forms between allergic and non-allergic asthma. In many cases a mixed form of asthma develops from an originally allergic asthma. Therefore the distinction is not always clear. This is because those affected react with asthma symptoms equally to certain allergens as well as to unspecific triggers. As the illness progresses, however, it is often the case that allergens are less frequently the trigger for symptoms.
Asthma is a chronic disease that places heavy demands on those affected: Self-monitoring of lung function with peak flow measurement and measurement of current inflammation values (FeNO measurement with Vivatmo), correct drug dosage and intake, breathing exercises to strengthen the lungs, monitoring of pollen levels, visits to the family doctor and lung specialist – all this is part of active asthma management. Patients who take this to heart can live a long and fruitful life in spite of their illness.
People who have difficult-to-manage asthma and who are not receiving adequate medication are at risk of developing severe uncontrolled asthma.
Up to 5 percent of asthma sufferers in Germany suffer from severe uncontrolled asthma. This means that:
- after an asthma attack, they get severe exacerbations, i.e. sputum, coughing, and shortness of breath, three times as often as other patients
- their lung function deteriorates at twice the rate of controlled patients
- they need more emergency medication
- the risk of an asthma attack becoming an emergency is almost twice as high as with controlled asthma
- patients are additionally often troubled by other complaints, such as headaches
If you want to assess your own asthma condition, the Deutsche Atemwegsliga e.V. (www.atemwegsliga.de) recommends the Asthma Control Test.
Asthma is not curable. Early diagnosis and treatment are therefore beneficial for all types of asthma. Regular monitoring and treating asthma with drugs can have a positive influence on the course of the disease.