Eczema
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Atopic dermatitis is a chronic (long-lasting) disease that
affects the skin. It is not contagious; it cannot be passed from one
person to another. The word "dermatitis" means inflammation of the skin.
"Atopic" refers to a group of diseases where there is often an inherited
tendency to develop other allergic conditions, such as asthma and hay
fever. In atopic dermatitis, the skin becomes extremely itchy.
Scratching leads to redness, swelling, cracking, "weeping" clear fluid,
and finally, crusting and scaling. In most cases, there are periods of
time when the disease is worse (called exacerbations or flares) followed
by periods when the skin improves or clears up entirely (called
remissions). As some children with atopic dermatitis grow older, their
skin disease improves or disappears altogether, although their skin
often remains dry and easily irritated. In others, atopic dermatitis
continues to be a significant problem in adulthood.
Atopic dermatitis is often referred to as "eczema," which
is a general term for the several types of inflammation of the skin.
Atopic dermatitis is the most common of the many types of eczema.
Several have very similar symptoms.
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Atopic dermatitis is very common. It affects males and
females and accounts for 10 to 20 percent of all visits to
dermatologists (doctors who specialize in the care and treatment of skin
diseases). Although atopic dermatitis may occur at any age, it most
often begins in infancy and childhood. Scientists estimate that 65
percent of patients develop symptoms in the first year of life, and 90
percent develop symptoms before the age of 5. Onset after age 30 is less
common and is often due to exposure of the skin to harsh or wet
conditions. Atopic dermatitis is a common cause of workplace disability.
People who live in cities and in dry climates appear more likely to
develop this condition.
Although it is difficult to identify exactly how many
people are affected by atopic dermatitis, an estimated 20 percent of
infants and young children experience symptoms of the disease. Roughly
60 percent of these infants continue to have one or more symptoms of
atopic dermatitis in adulthood. This means that more than 15 million
people in the United States have symptoms of the disease.
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Allergic contact eczema (dermatitis): a red,
itchy, weepy reaction where the skin has come into contact with
a substance that the immune system recognizes as foreign, such
as poison ivy or certain preservatives in creams and lotions
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Atopic dermatitis: a chronic skin disease
characterized by itchy, inflamed skin
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Contact eczema: a localized reaction that includes
redness, itching, and burning where the skin has come into
contact with an allergen (an allergy-causing substance) or with
an irritant such as an acid, a cleaning agent, or other chemical
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Dyshidrotic eczema: irritation of the skin on the
palms of hands and soles of the feet characterized by clear,
deep blisters that itch and burn
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Neurodermatitis: scaly patches of the skin on the
head, lower legs, wrists, or forearms caused by a localized itch
(such as an insect bite) that become intensely irritated when
scratched
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Nummular eczema: coin-shaped patches of irritated
skin-most common on the arms, back, buttocks, and lower
legs-that may be crusted, scaling, and extremely itchy
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Seborrheic eczema: yellowish, oily, scaly patches
of skin on the scalp, face, and occasionally other parts of the
body
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Stasis dermatitis: a skin irritation on the lower
legs, generally related to circulatory problems
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In a recent analysis of the health insurance records of 5
million Americans under age 65, medical researchers found that
approximately 2.5 percent had atopic dermatitis. Annual insurance
payments for medical care of atopic dermatitis ranged from $580 to
$1,250 per patient. More than one-quarter of each patient's total health
care costs were for atopic dermatitis and related conditions. The
researchers project that U.S. health insurance companies spend more than
$1 billion per year on atopic dermatitis.
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The cause of atopic dermatitis is not known, but the
disease seems to result from a combination of genetic (hereditary) and
environmental factors.
Children are more likely to develop this disorder if one
or both parents have had it or have had allergic conditions like asthma
or hay fever. While some people outgrow skin symptoms, approximately
three-fourths of children with atopic dermatitis go on to develop hay
fever or asthma. Environmental factors can bring on symptoms of atopic
dermatitis at any time in individuals who have inherited the atopic
disease trait.
Atopic dermatitis is also associated with malfunction of
the body's immune system: the system that recognizes and helps fight
bacteria and viruses that invade the body. Scientists have found that
people with atopic dermatitis have a low level of a cytokine (a protein)
that is essential to the healthy function of the body's immune system
and a high level of other cytokines that lead to allergic reactions. The
immune system can become misguided and create inflammation in the skin
even in the absence of a major infection. This can be viewed as a form
of autoimmunity, where a body reacts against its own tissues.
In the past, doctors thought that atopic dermatitis was
caused by an emotional disorder. We now know that emotional factors,
such as stress, can make the condition worse, but they do not cause the
disease.
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Atopic pleat (Dennie-Morgan fold): an extra fold
of skin that develops under the eye
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Cheilitis: inflammation of the skin on and around
the lips
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Hyperlinear palms: increased number of skin
creases on the palms
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Hyperpigmented eyelids: eyelids that have become
darker in color from inflammation or hay fever
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Ichthyosis: dry, rectangular scales on the skin
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Keratosis pilaris: small, rough bumps, generally
on the face, upper arms, and thighs
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Lichenification: thick, leathery skin resulting
from constant scratching and rubbing
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Papules: small raised bumps that may open when
scratched and become crusty and infected
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Urticaria: hives (red, raised bumps) that may
occur after exposure to an allergen, at the beginning of flares,
or after exercise or a hot bath
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Symptoms (signs) vary from person to person. The most
common symptoms are dry, itchy skin and rashes on the face, inside the
elbows and behind the knees, and on the hands and feet. Itching is the
most important symptom of atopic dermatitis. Scratching and rubbing in
response to itching irritates the skin, increases inflammation, and
actually increases itchiness. Itching is a particular problem during
sleep when conscious control of scratching is lost.
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The appearance of the skin that is affected by atopic
dermatitis depends on the amount of scratching and the presence of
secondary skin infections. The skin may be red and scaly, be thick and
leathery, contain small raised bumps, or leak fluid and become crusty
and infected. The box on page 8 lists common skin features of the
disease. These features can also be found in people who do not have
atopic dermatitis or who have other types of skin disorders.
Atopic dermatitis may also affect the skin around the
eyes, the eyelids, and the eyebrows and lashes. Scratching and rubbing
the eye area can cause the skin to redden and swell. Some people with
atopic dermatitis develop an extra fold of skin under their eyes. Patchy
loss of eyebrows and eyelashes may also result from scratching or
rubbing.
Researchers have noted differences in the skin of people
with atopic dermatitis that may contribute to the symptoms of the
disease. The outer layer of skin, called the epidermis, is divided into
two parts: an inner part containing moist, living cells, and an outer
part, known as the horny layer or stratum corneum, containing dry,
flattened, dead cells. Under normal conditions the stratum corneum acts
as a barrier, keeping the rest of the skin from drying out and
protecting other layers of skin from damage caused by irritants and
infections. When this barrier is damaged, irritants act more intensely
on the skin.
The skin of a person with atopic dermatitis loses moisture
from the epidermal layer, allowing the skin to become very dry and
reducing its protective abilities. Thus, when combined with the abnormal
skin immune system, the person's skin is more likely to become infected
by bacteria (for example, Staphylo-coccus and Streptococcus) or viruses,
such as those that cause warts and cold sores.
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When atopic dermatitis occurs during infancy and
childhood, it affects each child differently in terms of both onset and
severity of symptoms. In infants, atopic dermatitis typically begins
around 6 to 12 weeks of age. It may first appear around the cheeks and
chin as a patchy facial rash, which can progress to red, scaling, oozing
skin. The skin may become infected. Once the infant becomes more mobile
and begins crawling, exposed areas, such as the inner and outer parts of
the arms and legs, may also be affected. An infant with atopic
dermatitis may be restless and irritable because of the itching and
discomfort of the disease. The skin may improve by 18 months of age,
although the infant has a greater than normal risk of developing dry
skin or hand eczema later in life.
In childhood, the rash tends to occur behind the knees and
inside the elbows; on the sides of the neck; around the mouth; and on
the wrists, ankles, and hands. Often, the rash begins with papules that
become hard and scaly when scratched. The skin around the lips may be
inflamed, and constant licking of the area may lead to small, painful
cracks in the skin around the mouth.
In some children, the disease goes into remission for a
long time, only to come back at the onset of puberty when hormones,
stress, and the use of irritating skin care products or cosmetics may
cause the disease to flare.
Although a number of people who developed atopic
dermatitis as children also experience symptoms as adults, it is also
possible for the disease to show up first in adulthood. The pattern in
adults is similar to that seen in children; that is, the disease may be
widespread or limited to only a few parts of the body. For example, only
the hands or feet may be affected and become dry, itchy, red, and
cracked. Sleep patterns and work performance may be affected, and
long-term use of medications to treat the atopic dermatitis may cause
complications. Adults with atopic dermatitis also have a predisposition
toward irritant contact dermatitis, where the skin becomes red and
inflamed from contact with detergents, wool, friction from clothing, or
other potential irritants. It is more likely to occur in occupations
involving frequent hand washing or exposure to chemicals. Some people
develop a rash around their nipples. These localized symptoms are
difficult to treat. Because adults may also develop cataracts, the
doctor may recommend regular eye exams.
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Each person experiences a unique combination of symptoms,
which may vary in severity over time. The doctor will base a diagnosis
on the symptoms the patient experiences and may need to see the patient
several times to make an accurate diagnosis and to rule out other
diseases and conditions that might cause skin irritation. In some cases,
the family doctor or pediatrician may refer the patient to a
dermatologist (doctor specializing in skin disorders) or allergist
(allergy specialist) for further evaluation.
A medical history may help the doctor better understand
the nature of a patient's symptoms, when they occur, and their possible
causes. The doctor may ask about family history of allergic disease;
whether the patient also has diseases such as hay fever or asthma;
and
about exposure to irritants, sleep disturbances, any foods that seem
to be related to skin flares, previous treatments for skin-related
symptoms, and use of steroids or other medications. A preliminary
diagnosis of atopic dermatitis can be made if the patient has three or
more features from each of two categories: major features and minor
features.
Currently, there is no single test to diagnose atopic
dermatitis. However, there are some tests that can give the doctor an
indication of allergic sensitivity.
Pricking the skin with a needle that contains a small
amount of a suspected allergen may be helpful in identifying factors
that trigger flares of atopic dermatitis. Negative results on skin tests
may help rule out the possibility that certain substances cause skin
inflammation. Positive skin prick test results are difficult to
interpret in people with atopic dermatitis because the skin is very
sensitive to many substances, and there can be many positive test sites
that are not meaningful to a person's disease at the time. Positive
results simply indicate that the individual has IgE (allergic)
antibodies to the substance tested. IgE (immunoglobulin E) controls the
immune system's allergic response and is often high in atopic
dermatitis.
Recently, it was shown that if the quantity of IgE
antibodies to a food in the blood is above a certain level, it is
diagnostic of a food allergy. If the level of IgE to a specific food
does not exceed the level needed for diagnosis but a food allergy is
suspected, a person might be asked to record everything eaten and note
any reactions. Physician-supervised food challenges (that is, the
introduction of a food) following a period of food elimination may be
necessary to determine if symptomatic food allergy is present.
Identifying the food allergen may be difficult when a person is also
being exposed to other possible allergens at the same time or symptoms
may be triggered by other factors, such as infection, heat, and
humidity.
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Major Features
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Intense itching
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Characteristic rash in locations typical of the
disease
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Chronic or repeatedly occurring symptoms
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Personal or family history of atopic disorders
(eczema, hay fever, asthma)
Some Minor Features
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Early age of onset
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Dry skin that may also have patchy scales or rough
bumps
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High levels of immunoglobulin E (IgE), an
antibody, in the blood
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Numerous skin creases on the palms
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Hand or foot involvement
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Inflammation around the lips
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Nipple eczema
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Susceptibility to skin infection
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Positive allergy skin tests
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Many factors or conditions can make symptoms of atopic
dermatitis worse, further triggering the already overactive immune
system, aggravating the itch-scratch cycle, and increasing damage to the
skin. These factors can be broken down into two main categories:
irritants and allergens. Emotional factors and some infections and
illnesses can also influence atopic dermatitis.
Irritants are substances that directly affect the skin
and, when present in high enough concentrations with long enough
contact, cause the skin to become red and itchy or to burn. Specific
irritants affect people with atopic dermatitis to different degrees.
Over time, many patients and their family members learn to identify the
irritants causing the most trouble. For example, frequent wetting and
drying of the skin may affect the skin barrier function. Also, wool or
synthetic fibers and rough or poorly fitting clothing can rub the skin,
trigger inflammation, and cause the itch-scratch cycle to begin. Soaps
and detergents may have a drying effect and worsen itching, and some
perfumes and cosmetics may irritate the skin. Exposure to certain
substances, such as solvents, dust, or sand, may also make the condition
worse. Cigarette smoke may irritate the eyelids. Because the effects of
irritants vary from one person to another, each person can best
determine what substances or circumstances cause the disease to
flare.
Allergens are substances from foods, plants, animals, or
the air that inflame the skin because the immune system overreacts to
the substance. Inflammation occurs even when the person is exposed to
small amounts of the substance for a limited time. Although it is known
that allergens in the air, such as dust mites, pollens, molds, and
dander from animal hair or skin, may worsen the symptoms of atopic
dermatitis in some people, scientists aren't certain whether inhaling
these allergens or their actual penetration of the skin causes the
problems. When people with atopic dermatitis come into contact with an
irritant or allergen they are sensitive to, inflammation-producing cells
become active. These cells release chemicals that cause itching and
redness. As the person responds by scratching and rubbing the skin,
further damage occurs.
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Common Irritants
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Wool or synthetic fibers
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Soaps and detergents
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Some perfumes and cosmetics
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Substances such as chlorine, mineral oil, or
solvents
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Dust or sand
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Cigarette smoke |
A number of studies have shown that foods may trigger or
worsen atopic dermatitis in some people, particularly infants and
children. In general, the worse the atopic dermatitis and the younger
the child, the more likely food allergy is present. An allergic reaction
to food can cause skin inflammation (generally an itchy red rash),
gastrointestinal symptoms (abdominal pain, vomiting, diarrhea), and/or
upper respiratory tract symptoms (congestion, sneezing, and wheezing).
The most common allergenic (allergy-causing) foods are eggs, milk,
peanuts, wheat, soy, and fish. A recent analysis of a large number of
studies on allergies and breastfeeding indicated that breastfeeding an
infant for at least 4 months may protect the child from developing
allergies. However, some studies suggest that mothers with a family
history of atopic diseases should avoid eating common allergenic foods
during late pregnancy and breastfeeding.
In addition to irritants and allergens, emotional factors,
skin infections, and temperature and climate play a role in atopic
dermatitis. Although the disease itself is not caused by emotional
factors, it can be made worse by stress, anger, and frustration.
Interpersonal problems or major life changes, such as divorce, job
changes, or the death of a loved one, can also make the disease
worse.
Bathing without proper moisturizing afterward is a common
factor that triggers a flare of atopic dermatitis. The low humidity of
winter or the dry year-round climate of some geographic areas can make
the disease worse, as can overheated indoor areas and long or hot baths
and showers. Alternately sweating and chilling can trigger a flare in
some people. Bacterial infections can also trigger or increase the
severity of atopic dermatitis. If a patient experiences a sudden flare
of illness, the doctor may check for infection.
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Treatment is more effective when a partnership develops
that includes the patient, family members, and doctor. The doctor will
suggest a treatment plan based on the patient's age, symptoms, and
general health. The patient or family member providing care plays a
large role in the success of the treatment plan by carefully following
the doctor's instructions and paying attention to what is or is not
helpful. Most patients will notice improvement with proper skin care and
lifestyle changes.
The doctor has two main goals in treating atopic
dermatitis: healing the skin and preventing flares. These may be
assisted by developing skin care routines and avoiding substances that
lead to skin irritation and trigger the immune system and the
itch-scratch cycle. It is important for the patient and family members
to note any changes in the skin's condition in response to treatment,
and to be persistent in identifying the treatment that seems to work
best.
Medications: New medications known as
immuno-modulators have been developed that help control
inflammation and reduce immune system reactions when applied to the
skin. Examples of these medications are tacrolimus ointment (Protopic)
and pimecrolimus cream (Elidel). They can be used in patients older than
2 years of age and have few side effects (burning or itching the first
few days of application). They not only reduce flares, but also maintain
skin texture and reduce the need for long-term use of
corticosteroids.
Corticosteroid creams and ointments have been used for
many years to treat atopic dermatitis and other autoimmune diseases
affecting the skin. Sometimes over-the-counter preparations are used,
but in many cases the doctor will prescribe a stronger corticosteroid
cream or ointment. When prescribing a medication, the doctor will take
into account the patient's age, location of the skin to be treated,
severity of the symptoms, and type of preparation (cream or ointment)
that will be most effective. Sometimes the base used in certain brands
of corticosteroid creams and ointments irritates the skin of a
particular patient. Side effects of repeated or long-term use of topical
corticosteroids can include thinning of the skin, infections, growth
suppression (in children), and stretch marks on the skin.
When topical corticosteroids are not effective, the doctor
may prescribe a systemic corticosteroid, which is taken by mouth or
injected instead of being applied directly to the skin. An example of a
commonly prescribed corticosteroid is prednisone. Typically, these
medications are used only in resistant cases and only given for short
periods of time. The side effects of systemic corticosteroids can
include skin damage, thinned or weakened bones, high blood pressure,
high blood sugar, infections, and cataracts. It can be dangerous to
suddenly stop taking corticosteroids, so it is very important that the
doctor and patient work together in changing the corticosteroid
dose.
Antibiotics to treat skin infections may be applied
directly to the skin in an ointment, but are usually more effective when
taken by mouth. If viral or fungal infections are present, the doctor
may also prescribe specific medications to treat those infections.
Certain antihistamines that cause drowsiness can reduce
nighttime scratching and allow more restful sleep when taken at bedtime.
This effect can be particularly helpful for patients whose nighttime
scratching makes the disease worse.
In adults, drugs that suppress the immune system, such as
cyclosporine, methotrexate, or azathioprine, may be prescribed to treat
severe cases of atopic dermatitis that have failed to respond to other
forms of therapy. These drugs block the production of some immune cells
and curb the action of others. The side effects of drugs like
cyclosporine can include high blood pressure, nausea, vomiting, kidney
problems, headaches, tingling or numbness, and a possible increased risk
of cancer and infections. There is also a risk of relapse after the drug
is stopped. Because of their toxic side effects, systemic
corticosteroids and immunosuppressive drugs are used only in severe
cases and then for as short a period of time as possible. Patients
requiring systemic corticosteroids should be referred to dermatologists
or allergists specializing in the care of atopic dermatitis to help
identify trigger factors and alternative therapies.
In rare cases, when home-based treatments have been
unsuccessful, a patient may need a few days in the hospital for intense
treatment.
Phototherapy: Use of ultraviolet A or B
light waves, alone or combined, can be an effective treatment for mild
to moderate dermatitis in older children (over 12 years old) and adults.
A combination of ultraviolet light therapy and a drug called psoralen
can also be used in cases that are resistant to ultraviolet light alone.
Possible long-term side effects of this treatment include premature skin
aging and skin cancer. If the doctor thinks that phototherapy may be
useful to treat the symptoms of atopic dermatitis, he or she will use
the minimum exposure necessary and monitor the skin carefully.
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Give lukewarm baths.
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Apply lubricant immediately following the bath.
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Keep child's fingernails filed short.
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Select soft cotton fabrics when choosing clothing.
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Consider using sedating antihistamines to promote
sleep and reduce scratching at night.
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Keep the child cool; avoid situations where
overheating occurs.
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Learn to recognize skin infections and seek
treatment promptly.
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Attempt to distract the child with activities to
keep him or her from scratching.
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Identify and remove irritants and allergens.
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Skin Care: Healing the skin and keeping
it healthy are important to prevent further damage and enhance quality
of life. Developing and sticking with a daily skin care routine is
critical to preventing flares.
A lukewarm bath helps to cleanse and moisturize the skin
without drying it excessively. Because soaps can be drying to the skin,
the doctor may recommend use of a mild bar soap or nonsoap cleanser.
Bath oils are not usually helpful.
After bathing, a person should air-dry the skin, or pat it
dry gently (avoiding rubbing or brisk drying), and then apply a
lubricant to seal in the water that has been absorbed into the skin
during bathing. In addition to restoring the skin's moisture,
lubrication increases the rate of healing and establishes a barrier
against further drying and irritation. Lotions that have a high water or
alcohol content evaporate more quickly, and alcohol may cause stinging.
Therefore, they generally are not the best choice. Creams and ointments
work better at healing the skin.
Another key to protecting and restoring the skin is taking
steps to avoid repeated skin infections. Signs of skin infection include
tiny pustules (pus-filled bumps), oozing cracks or sores, or crusty
yellow blisters. If symptoms of a skin infection develop, the doctor
should be consulted and treatment should begin as soon as possible.
Protection from Allergen Exposure: The
doctor may suggest reducing exposure to a suspected allergen. For
example, the presence of the house dust mite can be limited by encasing
mattresses and pillows in special dust-proof covers, frequently washing
bedding in hot water, and removing carpeting. However, there is no way
to completely rid the environment of airborne allergens.
Changing the diet may not always relieve symptoms of
atopic dermatitis. A change may be helpful, however, when the medical
history, laboratory studies, and specific symptoms strongly suggest a
food allergy. It is up to the patient and his or her family and
physician to decide whether the dietary restrictions are appropriate.
Unless properly monitored by a physician or dietitian, diets with many
restrictions can contribute to serious nutritional problems, especially
in children.
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Despite the symptoms caused by atopic dermatitis, it is
possible for people with the disorder to maintain a good quality of
life. The keys to quality of life lie in being well-informed; awareness
of symptoms and their possible cause; and developing a partnership
involving the patient or caregiving family member, medical doctor, and
other health professionals. Good communication is essential. (See "Tips
for Working With Your Doctor" on page 26.)
When a child has atopic dermatitis, the entire family may
be affected. It is helpful if families have additional support to help
them cope with the stress and frustration associated with the disease. A
child may be fussy and difficult and unable to keep from scratching and
rubbing the skin. Distracting the child and providing activities that
keep the hands busy are helpful but require much effort on the part of
the parents or caregivers. Another issue families face is the social and
emotional stress associated with changes in appearance caused by atopic
dermatitis. The child may face difficulty in school or with social
relationships and may need additional support and encouragement from
family members.
Adults with atopic dermatitis can enhance their quality of
life by caring regularly for their skin and being mindful of the effects
of the disease and how to treat them. Adults should develop a skin care
regimen as part of their daily routine, which can be adapted as
circumstances and skin conditions change. Stress management and
relaxation techniques may help decrease the likelihood of flares.
Developing a network of support that includes family, friends, health
professionals, and support groups or organizations can be beneficial.
Chronic anxiety and depression may be relieved by short-term
psychological therapy.
Recognizing the situations when scratching is most likely
to occur may also help. For example, many patients find that they
scratch more when they are idle, and they do better when engaged in
activities that keep the hands occupied. Counseling also may be helpful
to identify or change career goals if a job involves contact with
irritants or involves frequent hand washing, such as kitchen work or
auto mechanics.
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Although scientists are working to develop safer vaccines,
persons diagnosed with atopic dermatitis (or eczema) should not receive
the current smallpox vaccine. According to the Centers for Disease
Control and Prevention (CDC), a U.S. Government organization, persons
who have ever been diagnosed with atopic dermatitis, even if the
condition is mild or not presently active, are more likely to develop a
serious complication if they are exposed to the virus from the smallpox
vaccine.
People with atopic dermatitis should exercise caution when
coming into close physical contact with a person who has been recently
vaccinated, and make certain the vaccinated person has covered the
vaccination site or taken other precautions until the scab falls off
(about 3 weeks). Those who have had physical contact with a vaccinated
person's unhealed vaccination site or to their bedding or other items
that might have touched that site should notify their doctor,
particularly if they develop a new or unusual rash.
During a smallpox outbreak, these vaccination
recommendations may change. Persons with atopic dermatitis who have been
exposed to smallpox should consult their doctor about vaccination.
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Provide complete, accurate medical information.
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Make a list of your questions and concerns in
advance.
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Be honest and share your point of view with the
doctor.
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Ask for clarification or further explanation if
you need it.
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Talk to other members of the health care team,
such as nurses, therapists, or pharmacists.
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Don't hesitate to discuss sensitive subjects with
your doctor.
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Discuss changes to any medical treatment or
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Researchers supported by the National Institute of
Arthritis and Musculoskeletal and Skin Diseases and other institutes of
the National Institutes of Health are gaining a better understanding of
what causes atopic dermatitis and how it can be managed, treated, and,
ultimately, prevented. Some promising avenues of research are described
below.
Genetics: Although atopic dermatitis runs
in families, the role of genetics (inheritance) remains unclear. It does
appear that more than one gene is involved in the disease.
Research has helped shed light on the way atopic
dermatitis is inherited. Studies show that children are at increased
risk for developing the disorder if there is a family history of other
atopic disease, such as hay fever or asthma. The risk is significantly
higher if both parents have an atopic disease. In addition, studies of
identical twins, who have the same genes, show that in an estimated 80
to 90 percent of cases, atopic disease appears in both twins. Fraternal
(nonidentical) twins, who have only some genes in common, are no more
likely than two other people in the general population to both have an
atopic disease. These findings suggest that genes play an important role
in determining who gets the disease.
Biochemical Abnormalities: Scientists
suspect that changes in the skin's protective barrier make people with
atopic dermatitis more sensitive to irritants. Such people have lower
levels of fatty acids (substances that provide moisture and elasticity)
in their skin, which causes dryness and reduces the skin's ability to
control inflammation.
Other research points to a possible defect in a type of
white blood cell called a monocyte. In people with atopic dermatitis,
monocytes appear to play a role in the decreased production of an immune
system hormone called interferon gamma (IFN-γ), which helps regulate
allergic reactions. This defect may cause exaggerated immune and
inflammatory responses in the blood and tissues of people with atopic
dermatitis.
Faulty Regulation of Immunoglobulin E
(IgE): As already described in the section on diagnosis, IgE is
a type of antibody that controls the immune system's allergic response.
An antibody is a special protein produced by the immune system that
recognizes and helps fight and destroy viruses, bacteria, and other
foreign substances that invade the body. Normally, IgE is present in
very small amounts, but levels are high in 80 to 90 percent of people
with atopic dermatitis.
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Prevent scratching or rubbing whenever possible.
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Protect skin from excessive moisture, irritants,
and rough clothing.
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Maintain a cool, stable temperature and consistent
humidity levels.
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Limit exposure to dust, cigarette smoke, pollens,
and animal dander.
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Recognize and limit emotional stress.
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In allergic diseases, IgE antibodies are produced in
response to different allergens. When an allergen comes into contact
with IgE on specialized immune cells, the cells release various
chemicals, including histamine. These chemicals cause the symptoms of an
allergic reaction, such as wheezing, sneezing, runny eyes, and itching.
The release of histamine and other chemicals alone cannot explain the
typical long-term symptoms of the disease. Research is underway to
identify factors that may explain why too much IgE is produced and how
it plays a role in the disease.
Immune System Imbalance: Researchers also
think that an imbalance in the immune system may contribute to the
development of atopic dermatitis. It appears that the part of the immune
system responsible for stimulating IgE is overactive, and the part that
handles skin viral and fungal infections is underactive. Indeed, the
skin of people with atopic dermatitis shows increased susceptibility to
skin infections. This imbalance appears to result in the skin's
inability to prevent inflammation, even in areas of skin that appear
normal. In one project, scientists are studying the role of the
infectious bacterium Staphylococcus aureus (S. aureus) in
atopic dermatitis.
Researchers believe that one type of immune cell in the
skin, called a Langerhans cell, may be involved in atopic dermatitis.
Langerhans cells pick up viruses, bacteria, allergens, and other foreign
substances that invade the body and deliver them to other cells in the
immune defense system. Langerhans cells appear to be hyper-active in the
skin of people with atopic diseases. Certain Langerhans cells are
particularly potent at activating white blood cells called T cells in
atopic skin, which produce proteins that promote allergic response. This
function results in an exaggerated response of the skin to tiny amounts
of allergens.
Scientists have also developed mouse models to study
step-by-step changes in the immune system in atopic dermatitis, which
may eventually lead to a treatment that effectively targets the immune
system.
Drug Research: Some researchers are
focusing on new treatments for atopic dermatitis, including biologic
agents, fatty acid supplements, and new forms of phototherapy. For
example, they are studying how ultraviolet light affects the skin's
immune system in healthy and diseased skin. They are also investigating
biologic agents, including several aimed at modifying the response of
the immune system. A biologic agent is a new type of drug based on
molecules that occur naturally in the body. One promising treatment is
the use of thymopentin to reestablish balance in the immune system.
Researchers also continue to look for drugs that suppress
the immune system. In this regard, they are studying the effectiveness
of cyclosporine A. Clinical trials are underway with another drug called
FK506, which is applied to the skin rather than taken orally. Also,
anti-inflammatory drugs have been developed that affect multiple cells
and cell functions, and may prove to be an effective alternative to
corticosteroids in the treatment of atopic dermatitis.
Several experimental treatments are being evaluated that
attempt to replace substances that are deficient in people with atopic
dermatitis. Evening primrose oil is a substance rich in gamma-linolenic
acid, one of the fatty acids that is decreased in the skin of people
with atopic dermatitis. Studies to date using evening primrose oil have
yielded contradictory results. In addition, dietary fatty acid
supplements have not proven highly effective. There is also a great deal
of interest in the use of Chinese herbs and herbal teas to treat the
disease. Studies to date show some benefit, but not without concerns
about toxicity and the risks involved in suppressing the immune system
without close medical supervision.
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Although the symptoms of atopic dermatitis can be
difficult and uncomfortable, the disease can be successfully managed.
People with atopic dermatitis can lead healthy, productive lives. As
scientists learn more about atopic dermatitis and what causes it, they
continue to move closer to effective treatments, and perhaps,
ultimately, a cure.
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National Institute of Arthritis and Musculoskeletal and
Skin Diseases
Centers for Disease Control and Prevention
American Academy of Dermatology
American Academy of Allergy, Asthma, and Immunology
National Eczema Association for Science and
Education
Food Allergy and Anaphylaxis Network (FAAN)
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