A new study carried out among the Norwegian population points to the increase in cases of atopic dermatitis (eczema) in children and infants. The cause: environmental factors such as the climate, but also the use of soaps and lotions that weaken the skin barrier and increase the risk of developing allergic eczema.
Dry and irritated skin, red patches, itching… The symptoms of atopic dermatitis, also known as allergic eczema, are well known. And for good reason: this inflammatory skin disease, which progresses in flare-ups, is increasingly widespread in industrialized countries, especially among young children and infants.
How to explain it? A new study by researchers from the University of Oslo, Norway, and published on the JAMA portalwas rightly interested in the factors of the increasing incidence of atopic dermatitis in children, especially in those under one year of age.
What is atopic dermatitis?
Atopic dermatitis is a common chronic, itchy inflammatory skin condition that affects children and adults worldwide. Characterized by periods of crises, where the patches appear suddenly, and periods of calm, this skin disease is most often observed from childhood, and more particularly in children who have genetic predispositions.
It is the most common skin condition in children, 15% of them are affected and around 80% of people with atopic dermatitis develop the disease before the age of 5.
Constant increase in eczema in children
Since the 1950s, doctors have seen an increase in the number of cases of atopic dermatitis in developed countries, and especially in urban populations. To understand why, the team of researchers led by Dr. Cathrine H. Mohn screened 295,286 medical prescriptions issued between 2009 and 2015 to treat atopic dermatitis in Norwegian children aged 0 to 6 years old.
They then calculated the incidence rate according to sex, age, calendar year and interactions, as well as the incidence rate according to the seasons.
The scientists were then able to observe that, with the exception of 2010, the incidence rate of atopic dermatitis has increased steadily. The overall incidence rate of atopic dermatitis increased from 0.028 per person-year in 2009 to 0.034 per person-year in 2014. And, in children under one year of age, the incidence rate increased from 0.052 per person-year in 2009 to 0.073 per person-year in 2014. That is, between 2009 and 2014, a 16.8% increase in allergic eczema in children.
More cases of dermatitis in spring and winter
According to Dr. Mohn and his colleagues, this rapid increase in the incidence rate of atopic dermatitis can be explained by environmental factors and lifestyles in genetically predisposed individuals.
Among them, seasonality and climate seem to play a decisive role. It is indeed in spring and winter that the cases of eczema in infants are the most numerous. In the spring, airborne pollen is to blame. The researchers admit, however, that “there are as yet no clear explanations for the seasonal peak in the incidence rate during the winter”. They argue, however, that the cold can alter the skin barrier.
Several additional environmental factors could explain the increased incidence of atopic dermatitis in children, especially those living in urban areas: air pollution and proximity to road traffic. Increased water hardness, exposure to tobacco smoke and psychological stress are also implicated. By being in contact with farm animals and the microbes associated with them, children living in rural areas benefit from a better education of their innate immune system (the body’s first line of defense). and therefore protection against abnormal immune responses causing atopic eczema.
Soaps and detergent lotions implicated
Finally, excessive hygiene and skin care practices in children could be an often overlooked environmental factor that may influence the risk of atopic dermatitis. Excessive use of detergent soaps and lotions can promote skin inflammation by damaging the skin barrier in genetically susceptible people.
The researchers explain that further clarification of risk predictors is now needed to reduce the risk of developing atopic dermatitis in children.
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