Atopic Dermatitis Health Article

Definition

Atopic dermatitis (AD) is a chronic skin disorder associated with biochemical abnormalities in the patient's body tissues and immune system. It is characterized by inflammation, itching, weepy skin lesions, and an individual or family history of asthma, hay fever, food allergies, or similar allergic disorders. Atopic dermatitis is also known as infantile eczema or atopic eczema. The word atopic comes from atopy, which is derived from a Greek word that means "out of place." Atopy is a genetic predisposition to type I (immediate) hypersensitivity reactions to various environmental triggers. It includes bronchial asthma and food allergies as well as atopic dermatitis.

Description

AD varies in severity but in general is characterized by red, weeping, crusted patches of inflamed skin that itch constantly. The distribution of the skin lesions depends on the child's age. In infants, the skin lesions are usually found on the face, scalp, diaper area, body folds, hands, and feet, and tend to be exudative (oozing fluid that has escaped from blood vessels as a result of inflammation). Infants old enough to crawl may have patches of inflamed skin on the neck and trunk as well. In older children, the affected areas are usually located on the wrists, ankles, back of the neck, insides of the elbows, and the backs of the knees. The skin lesions in older children are more likely to be lichenified than exudative. Lichenification is the medical term for a leather- or bark-like thickening of the outermost layer of skin cells (the epidermis) as a result of long-term scratching or rubbing of itching lesions. In addition, the normal markings of the skin are exaggerated in lichenification.

The lesions of AD are accompanied by intense pruritus, which is the medical term for itching. Children with atopic dermatitis often have a lowered threshold of sensitivity to itching, which means that they feel itching sensations more intensely than children without the disorder. The pruritus often creates a vicious cycle of itching and scratching, which leads to more widespread rash, which leads to more itching. The child may scratch the affected skin only intermittently during the day, however. It is common for children with AD to do more scratching in the early evening and at night; moreover, disruptions of normal sleep patterns are common in these children.

Transmission

Atopic dermatitis is not contagious but may affect several members of the same family at the same time.

Demographics

Atopic dermatitis is a very common condition in the general population. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), about 15 million people in the United States have one or more symptoms of the disease. It accounts for 15 to 20 percent of all visits to dermatologists (doctors who specialize in treating diseases of the skin). About 20 percent of infants develop symptoms of atopic dermatitis. Moreover, the proportion of people affected by AD is increasing; the American Academy of Allergy, Asthma, and Immunology (AAAAI) began a long-term study in 1999 that indicates that a larger percentage of children are affected by AD than was the case in the 1980s. This rise in prevalence is true of all developed countries, not just the United States and Canada. People who immigrate to Europe or North America from under-developed countries have increased rates of atopic dermatitis, which suggests that environmental factors play a role in the development or triggering of the disorder.

Atopic dermatitis begins early in life; about 65 percent of patients with AD develop symptoms during the first 12 months of life, with 90 percent showing symptoms before five years of age. The most common age for the onset of symptoms in infants is between six and 12 weeks of age. It is unusual for adults over the age of 30 to develop AD for the first time.

There is some disagreement among researchers with regard to race or ethnicity as risk factors for atopic dermatitis. Some studies indicate that all races and ethnic groups are equally at risk, while others suggest that Asians and Caucasians have slightly higher rates of AD than African Americans or Native Americans. Some skin lesions typical of AD may be more difficult to evaluate in African Americans because of the underlying skin pigmentation. With regard to sex, males and females appear to be equally at risk.

Atopic dermatitis is a major economic burden on families with children affected by the disorder. One researcher in Australia stated that the stresses on families with children diagnosed with moderate or severe AD are greater than the burdens on families with children with type 1 diabetes. These stresses include loss of sleep, loss of employment for the parents, time taken for direct care of the skin disorder, and the financial costs of treatment. The National Institutes of Health (NIH) estimates that atopic dermatitis costs U.S. health insurance companies more than $1 billion every year.