What causes psoriasis?

No one knows exactly what causes psoriasis, but most researchers now conclude that it is related to the immune system (psoriasis is often called an "immune-mediated" disorder). In psoriasis, the immune system is somehow triggered, which in turn speeds up the growth cycle of skin cells. A normal skin cell matures in 28 to 30 days and is shed from the skin's surface unnoticed. But a psoriatic skin cell takes only 3 to 4 days to mature and move to the surface, and the cells pile up and form the elevated red lesions.

Who gets psoriasis?

Psoriasis appears to be slightly more prevalent in women than men. The average age of diagnosis is 28, and psoriasis most commonly appears between the ages of 15 and 35. However, it can develop at any time—a first-time diagnosis of psoriasis has been seen in very old people and in new-born babies and small children. Psoriasis in infants is considered rare, although between 10 percent and 15 percent of those with psoriasis get it before age 10. About 150,000 to 260,000 new cases of psoriasis are diagnosed each year.

How is psoriasis diagnosed?

No special blood test or other diagnostic tool exists for psoriasis. The diagnosis is usually determined through examination of the skin by a physician or other health care provider. Less commonly, a skin biopsy is examined under the microscope for biological evidence of psoriasis. The presence of small pits in the fingernails is also an indicator of psoriasis.

Is psoriasis contagious?

No, psoriasis is not contagious. It is not something you can "catch" or "pass on." Lesions of psoriasis may be unsightly, but they should not be regarded as an infection or an open wound. An individual with psoriasis poses no threat to the health or safety of others.

What parts of the body are affected?

Psoriasis most commonly appears on the scalp, knees, elbows and torso. But psoriasis can develop anywhere, including the nails, palms, soles, genitals and face (which is rare). Often the lesions appear in a symmetrical fashion, in the same place on the right and left sides of the body.

Do people know they are going to get psoriasis?

It is not possible to predict who will get psoriasis, although heredity clearly plays a role in predisposing people to develop the disease. A family association exists in one out of three cases. However, there is no established pattern of inheritance, so many people cannot trace a family history of psoriasis. The National Psoriasis Foundation has created and continues to support the National Psoriasis Tissue Bank to facilitate worldwide investigation into the genetic causes of psoriasis and psoriatic arthritis. Environmental factors such as physical trauma to the skin, infections, stress and reactions to certain drugs may trigger the onset of psoriasis, even in people without an apparent family history of psoriasis.

Is there a cure for psoriasis?

There is no cure, but there are many different treatments, both topical and systemic, that can clear psoriasis for periods of time. Experimentation is often required to find a treatment that works for a particular person. Some people who have psoriasis experience spontaneous remissions, but no one knows why this happens and they are unpredictable.

Do people die from psoriasis?

Yes. About 400 people die from complications caused by psoriasis each year. Primarily, such complications occur in relation to a severe, extensive form of psoriasis, such as generalized pustular psoriasis or erythrodermic psoriasis, where large areas of skin are shed. The skin plays an important role in regulating body temperature and serving as a barrier to infection. When a person's skin is compromised to such a great extent, secondary infections are possible. Fluid loss is a complicating factor in these serious forms of psoriasis, and a great strain is also placed on the circulatory system. Also, approximately 400 people receive social security disability due to psoriasis each year.

Is psoriasis associated with other diseases?

Between 10 percent and 30 percent of people who have psoriasis will also develop psoriatic arthritis, which is similar to rheumatoid arthritis but generally milder. Psoriatic arthritis causes inflammation and stiffness in the soft tissue around joints, and it frequently involves the fingers and toes.Other parts of the body can be affected as well, including the wrists, neck, lower back, knees and ankles. In severe cases, psoriatic arthritis can be destructive to joints and disabling.

Can people with psoriasis function normally?

For the most part, people with psoriasis function normally. Sometimes people experience low self-esteem because psoriasis is unsightly. Psoriasis is often misunderstood by the public, which can make social interactions awkward. This may lead to emotional problems such as anxiety, anger, embarrassment and depression. Psoriasis can affect the type of work people do if it is visible.

What is the economic impact of psoriasis?

Psoriasis is a chronic illness that, in many cases, requires continuous treatment. The cost of medications and visits to the doctor are ongoing. Severe cases may require periods of hospitalization. It is estimated that 56 million hours of work are lost each year by people who suffer from psoriasis, and between $1.6 billion and $3.2 billion is spent annually on treating psoriasis.

Is there hope that a cure will be found?

Yes. There is more research activity into psoriasis going on today than ever before. Tremendous progress has been made in understanding psoriasis, both in terms of the immune system problems related to the disease and the underlying genetic causes. The National Psoriasis Foundation and the federal government are promoting and funding research to find the cause and cure for psoriasis.