Introduction

Respiratory experts now widely acknowledge that asthma is a collection of symptoms with many possible underlying causes. As opposed to a single condition with a single cause, as its name suggests. Asthma attacks are caused by constriction of smooth muscle in the body’s ‘airways’. There are many possible reasons why smooth muscle might go into spasm. Asthma is a symptom. Consider how many reasons there are behind a symptom like sneezing. There may be just as many reasons why one might have asthma attacks. Here are a few worth considering.

Asthma Caused By Allergens

One of the most common causes of asthma is specific reactions to substances known as allergens. When inhaled, these allergens (dust, pollen, mould, cigarette smoke, etc) cause an avalanche of immune responses, primarily the release of antibodies such as immunoglobulin E (IgE). When released in excess, allergens start attaching to the surface of mast cells on immunoglobulin E antibodies, releasing histamine and other bioactive mediators. The body reacts to this by causing bronchoconstriction (tightening of the airways), secretion of secretory cells, and other immune responses. Repeated exposure to allergens can exacerbate both the frequency and severity of asthmatic episodes caused by allergens.

Asthma Caused By Genetics 

Most people intuitively know that if the parents of a child have asthma, the probability of them having the same pattern substantially increases. Most research suggests that approximately 55–74% of adults and 90% of children have a genetic component behind the development of asthma. Genetic predisposition to asthma involves immune regulation, inflammation, and airway responsiveness. Interestingly, no single mutation in one gene results in the disease passing through generations to their offspring. Instead, asthma can be considered a polygenic, multifactorial disorder, meaning their genetics and environment (early-life stressors, upbringing, social surroundings) intertwine and cause asthma.

Asthma Caused By Respiratory Infections

Respiratory infections are relatively common and are usually short-lasting in nature. However, for individuals who already have asthma or a genetic and environmental predisposition, viral respiratory tract infections can have a drastic impact on either the expression or the control of the disease. Recent research has shown that Rhinovirus (RV) induced wheezing below the age of six substantially increases the probability of delayed diagnosis of asthma in later years. While the mechanism of action on how respiratory infections cause asthma, evidence suggests that individuals with deficiencies in antiviral activity and a weakening epithelial barrier in the airway have a significantly higher risk of developing asthma caused by respiratory infections.

Asthma Caused By Air Pollution

The World Health Organisation defines air pollution as ‘The contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere’. While the causal relationship between asthma and air pollution remains up for discussion, multiple studies have shown increasingly consistent evidence behind prolonged exposure to air pollutants and asthmatic onset and exacerbations. 

It is estimated that around 400,000 people in Europe die every year from nitrogen dioxide (NO2), ozone (O3) and other high concentrations of suspended particles. The correlation between air pollution and health is so severe that global life expectancy has decreased by at least one year. Furthermore, An estimated 13% of children diagnosed with asthma can be directly attributed to NO2 exposure.  

Asthma Caused By Exercise: 

It is estimated that 40-90% of people diagnosed with asthma develop exercise-induced bronchoconstriction (EIB). It is defined as the narrowing of the bronchial airways during strenuous exercise. The exact cause behind how exercise causes asthma isn’t fully understood. It was assumed that a higher cold air intake was the biggest contributor. However, recent research shows that dry air is the main culprit. During exercise, air consumption increases from 12 litres to 100 litres, a 40-60 fold increase. The rapid inhalation and exhalation of air causes air passages to dehydrate and constrict, limiting airflow consumption. This mechanism of action is exacerbated when exercising in the presence of air pollutants due to their capacity to irritate the epithelial lining of the airway.   

Asthma Caused By Weather Changes

Weather changes (heat, humidity, air pressure, etc.), especially sudden drastic changes seen in extreme weather events, can directly cause asthmatic symptoms. The variability of daily weather events, or even seasonal changes, can act as indirect triggers for asthmatic sufferers. In hotter climates, mixing sunlight and air pollution can create smog. Cold changes cause a drying of the airways, causing them to become more sensitive and constricted. Higher humid conditions are a perfect environment for developing mould and dust mites, which can cause asthma. Finally, thunderstorms and the subsequent downpour of rain cause the breakdown of stagnant pollen, making it easier to travel freely in the air. 

Asthma Caused By Stress & Trauma

Even though many of us still find it surprising to learn that there is a connection between conditions like asthma and stress, perhaps we shouldn’t. Stress and breathing are deeply connected, after all. Beyond that, plenty of research has shown the connection between conditions like asthma and life stressors, both past and present.

It will be a long time before science fully unpacks the mechanisms by which stress and trauma induce asthma. Yet in the meantime, understanding that it does can potentially open up a far deeper understanding of asthma for many sufferers. Moving beyond the old-fashioned idea of asthma as a disease that you just have to live with and instead acknowledging that it has complex connections to the ‘whole human’ experience is a big step in the right direction when choosing asthma treatment options.

Asthma Caused By Spinal Irritation

A rarer but nonetheless very real cause of asthma is irritation of the spinal nerves. The nerve roots that leave the spine innervate the smooth muscle in the lungs, and so it follows that irritation of the nerves themselves can cause asthma-like symptoms.

This means that issues like whiplash, poor posture and injuries to the upper back can easily cause symptoms that at least appear to be exactly like normal asthma. And in truth, there may not even be any ‘normal’ asthma. Asthma attacks are a symptom with many possible causes. And perhaps surprisingly, irritation/injury to the spinal nerves is on the list.