What is Atopic Dermatitis? What Causes It?

Dermatologist Fatma Yıldız – Ankara Life Polyclinic

Atopic dermatitis (AD) is a chronic, itchy, inflammatory skin disease that progresses with periods of attack and remission. Derived from the Greek word “atopos”, “atopy” means unfounded, unclassifiable. Although it entered the medical literature in the 20th century, historical findings of AD date back to 69-140 AD. Besnier first described in 1892 that atopic dermatitis could be seen together with allergic rhinitis and asthma. Starting in the 1930s, the term “atopic dermatitis” began to be used, and over time, the disease was also referred to by names such as “atopic eczema”, “neurodermitis constitutionalis”, and “endogenous eczema”.

Major and minor diagnostic criteria were determined by Hanifin and Rajka in the 1980s, and these criteria were adapted for use in epidemiological studies by the Great Britain Study Group in 1994. The diagnosis of AD is difficult due to its different morphological appearances and recurrent structure. The diagnosis is made by evaluating the clinical findings and excluding other possibilities. Some authors classify patients with high IgE levels as extrinsic AD, and those without IgE as intrinsic AD or atopiform dermatitis; but this distinction is still controversial.

Indices such as SCORAD (Score in Atopic Dermatitis) and EASI (Eczema Area and Severity Index) are used in the diagnostic process; the disease is graded as mild, moderate and severe. AD is a common disease affecting 20-25% of children and 2-3% of adults. It is characterized by atopic tendency, personal or familial type 1 allergy, bronchial asthma, allergic rhinitis and increased IgE.

Disease Onset and Frequency

AD usually begins in infancy, between 3-6 months. Although most cases improve during adolescence, the disease continues in a group of 10-30%. In a small number of patients, AD begins in adulthood. After World War II, an increase in atopic dermatitis cases was observed due to the effects of industrialization, urbanization and climate change. In industrialized countries, it is seen in 15-30% of children and 2-10% of adults. In studies conducted in Türkiye, the frequency was found to be 4.3% in children aged 6-13 and 8.1% in children aged 10-11.

Effects of AD and Risk Factors

AD significantly reduces the quality of life of patients by causing the development of anxiety and depression. It is more common in women. 60-70% of AD patients have a family history. This rate increases 2-fold if one parent is atopic and 3-fold if both parents are atopic. Atopic history in the mother is one of the strongest risk factors for the development of AD in the child.

Genetic and environmental factors play a role together in the development of AD. House dust mites, food allergies, pollen, pets, cigarette smoke, soap and detergents are among the factors that trigger the disease. The meta-analysis conducted by Gdalevich and colleagues has shown that breastfeeding has a protective effect against AD.

Hygiene Hypothesis and Environmental Effects

According to the hygiene theory put forward by Strachan, exposure to various infections in early childhood ensures the development of immune tolerance and the incidence of atopic diseases decreases. Therefore, the incidence of AD is lower in children growing up in rural areas. Although early contact with pets may seem risky, some studies have indicated that a certain level of allergen exposure may have protective effects.

Irritants and Microbial Effects

Irritants are more important triggers than allergens in atopic dermatitis. Low humidity and excessive contact with soap and water sensitize the skin. In individuals with AD, Staphylococcus aureus colonization of the skin is common. This bacterium causes both direct inflammation and exacerbations through superantigens. Exposure to environmental cigarette smoke also increases the risk of AD.

For example, in a study conducted with 421 children, the risk of developing AD doubled if the mother smoked during pregnancy or breastfeeding. It has been reported that prenatal factors such as birth weight, maternal age, and contraceptive use may also have an effect on atopic dermatitis. In addition, advanced maternal age and fetal growth patterns are thought to be associated with susceptibility to the disease.

Prognosis and Adult AD

Factors such as dry skin, a history of widespread dermatitis in childhood, family history of asthma or allergic rhinitis, high IgE levels, female gender, and being an only child are associated with the continuation of AD in adulthood. These factors carry negative predictions in terms of prognosis.

As Ankara Life Polyclinic, under the leadership of Dermatologist Doctor Fatma Yıldız, clinical diagnostic criteria, risk factors and personalized treatment protocols are handled in accordance with scientific guidelines for patients with atopic dermatitis. A holistic approach is offered in the management of AD with correct diagnosis, effective care and environmental control recommendations in every age group from infancy to adulthood.