Eczema, often referred to as atopic dermatitis (AD) in the literature, is the most common form of chronic dermatitis. This non-contagious skin condition manifests as an itchy rash, predominantly affecting children. Over time, symptoms usually improve, though adults can experience it too.
Unraveling the underlying triggers of this condition, however, isn’t straightforward. Present understanding implies that a blend of genetic and environmental influences play a role. In simpler terms, it appears both the individual’s genetic makeup and their surrounding environment contribute to its emergence.
This initial explanation may not fully satisfy the curiosity of those interested in this skin ailment. Nonetheless, we intend to probe further, aiming to offer a more detailed understanding of its multifaceted origins.
Unraveling Eczema: Two Key Theories
While we understand eczema’s mechanisms, the specific factors triggering them remain under academic debate. Two prevalent hypotheses have emerged.
The first hypothesis suggests that an imbalance in the immune system is a leading cause. The second theory points to a defect in the skin barrier.
These hypotheses offer plausible explanations, despite the lack of a definitive answer to Atopic dermatitis’s cause.
Importantly, we should not consider these hypotheses in isolation. Rather, we should view them as complementary perspectives, each adding valuable insight to our understanding of this complex condition.
The imbalance in the immune system hypothesis
The first theory proposes that eczema arises from an imbalance in the production of T cells .
Individuals with Atopic dermatitis often have an overabundance of T-helper 1 and T-regulatory cells.
This imbalance results in an increased production of interleukins, substances that amplify the body’s inflammatory response. Consequently, the inflammation intensity in the body’s affected areas heightens.
The skin barrier hypotheses
The newer theory suggests that mutations in the filaggrin gene increase eczema risk. Filaggrin binds upper skin layer cells and seals tiny cracks, preventing water loss and allergen penetration. In those with the mutation, filaggrin production drops, impairing the skin barrier and making the skin more permeable to water, allergens, and microorganisms.
The toll on health goes beyond the skin surface
Let’s take a pause from eczema causes here and briefly discuss the phenomenon known as “The Atopic March.”
The immune system’s defects often have body-wide effects. Atopic dermatitis, while a skin condition, is influenced by genetic factors affecting other body parts. “The Atopic March” describes conditions stemming from a flawed immune response often seen in eczema patients, including a flaw in T-helper cells.
lymphocyte function also can cause food allergies, asthma or allergic rhinitis. The Atopic dermatitis kicks in first and, in the early years of life, is often followed by the rest of the atopic cascade. The importance of this phenomenon lies in the fact that a timely treatment of eczema can reduce the severity of or prevent in temporary conditions that follow it.
Environmental factors of Atopic dermatitis
As mentioned earlier, the leading cause of eczema is a combination of genetic and environmental factors. Not all people with the “right genetic code” develop the condition. Atopic dermatitis happens only if all or the majority of contributing factors align, creating a perfect storm. In this section, we’ll take a look at contributing environmental factors. The prevalence (the number of cases of a disease present in a particular population in a given time) of eczema has increased in the past few decades at a pace that changes in gene pool cannot explain. So, the increase in prevalence is explained by changes in environmental factors. At this moment, we can’t tell for sure what those factors are. Still, the growing body of scientific evidence suggests that exposure to dust mites, various allergens, infections, irritants and antibiotics increases the prevalence of Atopic dermatitis 1.
Hygiene Hypothesis
The theory was introduced to the public back in 1989, and it suggests that the main cause of increased eczema prevalence may be the development and “sanitization” of society. The theory argues that the lack of adequate stimulation of the immune system in early life (children that are “too clean”) and failure of maintaining balanced gut flora in adulthood (antibiotics in food) are triggering factors in the pathogenesis of Atopic dermatitis. Furthermore, the hygiene hypothesis explains the rapid rise in prevalence among smaller, wealthier and more educated families in comparison with larger families and those attending a nursery.
The bottom line is that exposure to some pathogens in early life, as well as the timing of exposure, play an essential role in the pathogenesis of eczema. However, some pathogens may trigger the condition; for example, measles infection increases the risk of the disease.
References : 2,3,4,5
Irritants 6,7,8,9,10,11,12
Soap acts as an irritant. It causes skin dryness, increases its pH, and transepidermal water loss. Several studies have shown that exposure to soap is in relation to increased eczema prevalence and that removal or avoidance of such chemicals reduces its prevalence.
Some studies have shown that eczema prevalence is increased in areas with harder water, but in recent years this hypothesis has been rejected. Namely, the increased hardness of water requires increased use of soap, so the scientific community accepted the use of irritants as the cause of Atopic dermatitis rather than the water harness.
The avoidance of irritants early in life is vital as a preventive measure – once the condition establishes, exclusion of those chemicals do not affect further development of the disease (eczema, followed by atopic march).
So, what is the main cause of Eczema?
After this discussion, it is essential to underline that eczema is a multifactorial disease. Its causes are not yet fully understood, and some claims about it are still wrapped in a veil of controversy. However, here are some important takeaway notes:
– The condition is a multifactorial disease caused by a combination of genetic and environmental factors.
– The genetic mutations in people with eczema affect not only the skin but potentially other organ systems, primarily respiratory organs. Atopic dermatitis is often only the first in a cascade of health issues that arise from altered genes.
– Restriction from exposure to the microbes in the environment is in association with the increased prevalence of eczema, but some infective agents may increase the chance of disease establishment.
– Once the condition establishes, it is impossible to reverse the process, but it tends to milden or completely disappear during puberty.
– Exposure to skin irritants, soap in the first place, plays an important role in the pathogenesis of the disease.