Hello everyone and welcome to this week's blog post. In this week's article, I will be discussing asthma. I will first explain what asthma is and the symptoms of the disease. I will then examine the possible causes behind this disease, before explaining how it can be treated.
What is asthma?
Asthma is a serious disease, affecting around 300 million people worldwide. Asthma is a long-term health condition that affects the airways in the lungs, in particular the smaller airways. These small airways have an inner layer called the mucosa surrounded by a layer of smooth muscle. Those suffering from asthma have chronic inflammation of these airways, causing them to become swollen and narrow. In addition, the airways can also produce excess mucus.
Certain triggers can also cause an asthma attack. This is when the rings of smooth muscle surrounding the small airways contract, thus reducing the diameter of the airways. This trigger also causes the mucosa lining to become inflamed and produce more mucus.
This can severely restrict the flow of air through these airways, causing an asthma attack.
There are many different symptoms of asthma, which vary depending on the patient. Many sufferers of asthma report experiencing a tight constriction around their chest - this symptom is caused by the smooth muscles contracting.
Furthermore, since air is now passing through a narrower space, a whistling sound can also be heard. The increased mucus production also results in increased coughing. In addition, those suffering from an asthma attack can also feel too breathless to speak or eat.
Those suffering from severe asthma find it much harder to expel air from the lungs than inhale air. Therefore, this can lead to a condition called hyperinflated lungs, where the air gets trapped inside the lungs, reducing the exchange of oxygen and carbon dioxide between the air and the blood. In severe cases, this can lead to death as the body is not able to oxygenate.
There are many different types of asthma. While they share these symptoms, they differ in the things that they are triggered by. For example, some types of asthma are triggered by exercise. This is because, as you exercise, your lungs become warmer so the exhaled air has higher water content. This can dry out the airways in the lungs, triggering asthma symptoms. Meanwhile, allergic asthma can be triggered by allergies including pollen, dust mites and mould.
Unfortunately, the World Health Organisation estimates that asthma causes 250,000 people to die prematurely each year. Consequently, it is important that those who are suffering from asthma are identified and offered treatment. In addition, it is also important that those who suffer from asthma attacks or feel that their asthma isn't being controlled talk to the doctor or specialist nurse responsible for their care, as their asthma treatment plan may need changing.
How is asthma caused?
We do not yet fully understand why some people are affected by others whereas others aren't, however, scientists believe that asthma is caused by a combination of genetic and environmental factors.
For example, one of the reasons that asthma can be caused by genetic factors is that allergies can be inherited from parents. This increases the risk of asthma, as these allergens can be inhaled into the lungs. The immune system would then react to these allergens, causing inflammation of the airways.
In addition, there are also other genetic factors responsible for asthma. According to a paper published in the European Clinical Respiratory Journal, it is generally accepted that the children of parents who suffer from asthma are more likely to suffer from the disease themselves. However, asthma is a polygenetic disease - it is not caused by a single mutation on a single gene but rather an accumulation of lots of different mutations on different genes. This makes it much harder for researchers to ascertain the specific genes responsible for asthma.
Moreover, asthma can also be caused by environmental factors. One of the main environmental factors that can increase the likelihood of asthma is smoking. Smoking is a major contributor to adult-onset asthma, as smoking causes inflammation of the airways and increased mucus production, making it harder to breathe. In addition, children also have an increased risk of getting asthma if they are exposed to second-hand smoke or if the mother smokes during pregnancy.
Furthermore, irritants in the environment also increase the risk of getting asthma. For example, fumes from traffic and chemical plants can cause air pollution, which irritates the lungs. According to Asthma UK, this factor is one reason why children who live closer to roads are more likely to get asthma.
Over the last several decades, the number of sufferers from asthma has increased significantly (although this number has plateaued in the last few years). There are likely several reasons for this increase, including the increase in pollutants in the atmosphere and improved diagnostic rates.
Another theory behind this recent increase in the number of patients suffering from asthma has been called the 'hygiene hypothesis'. In recent years, there has been an increase in hygiene (e.g. through washing hands) and a reduction in the spread of transmissible diseases. The hygiene hypothesis states that this causes the immune system of young children to not get activated as much, and thus not develop correctly. As a result, this may cause the immune system to become hypersensitive, making the person more susceptible to allergies and asthma.
How can asthma be treated?
Unfortunately, we do not currently have a cure for asthma. However, there are treatments available that can help relieve the symptoms and allow patients to live a normal lifestyle. Most people who suffer from asthma in the UK will be provided with a reliever inhaler. This is a device which ejects an aerosolised power or mist that can be inhaled.
This reliever inhaler can be used to treat symptoms immediately. This is because the inhaler ejects a medicine containing beta-agonists. These chemicals act on beta-adrenoceptors in the airways of the lungs, causing the smooth muscle to relax and thus allowing the person to breathe properly.
How can asthma be prevented?
In addition, medications can also be taken prophylactically to try and prevent the symptoms of asthma. For example, if you are finding it difficult to manage your asthma, then you may be prescribed a preventer inhaler.
These inhalers contain corticosteroids that reduce sensitivity and inflammation in the lungs. Not only does this reduce the likelihood of an asthma attack occurring, but it also reduces the damage caused by chronic inflammation, thus reducing scarring in the airways.
For those suffering from severe asthma which can't be controlled with inhalers, there are other treatments available. These include tablets or syrups that can be used to reduce inflammation and injections that reduce the amount of IgE (an antibody produced by the body in response to an allergen). Furthermore, according to the NHS, a procedure called bronchial thermoplasty can be performed. This procedure is where a tube is passed down the airways and heat is applied to the smooth muscle, helping them to widen.
The other main way to prevent asthma is to remove triggers in the environment. This could be achieved by reducing the allergens present in the patient's house or workplace. Air filters could also be used to reduce the pollutants present in the air.
Preventing asthma attacks occurring is very important for several reasons. Firstly, it is much better for the patients, as they don't have to go through the pain of an asthma attack or deal with the long-term implications of chronic inflammation. In addition, reducing the number of asthma attacks also reduces demand on the NHS and ambulance services, allowing the NHS to treat more patients.
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Sources:
D'Amato G, Vitale C, Molino A, et al. Asthma-related deaths. Multidiscip Respir Med. 2016;11:37. Published 2016 Oct 12. doi:10.1186/s40248-016-0073-0
Thomsen SF. Genetics of asthma: an introduction for the clinician. Eur Clin Respir J. 2015;2:10.3402/ecrj.v2.24643. Published 2015 Jan 16. doi:10.3402/ecrj.v2.24643
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