What is Psoriasis?

Psoriasis is an inflammatory skin condition. There are five types, each with unique signs and symptoms. Between 10% and 30% of people who develop psoriasis get a related form of arthritis called “psoriatic arthritis,” which causes inflammation of the joints.

Plaque psoriasis is the most common type of psoriasis. About 80% of people who develop psoriasis have plaque psoriasis, which appears as patches of raised, reddish skin covered by silvery-white scale. These patches, or plaques, frequently form on the elbows, knees, lower back,
and scalp. However, the plaques can occur anywhere on the body.

The other types are guttate psoriasis (small, red spots on the skin),
pustular psoriasis (white pustules surrounded by red skin), inverse psoriasis (smooth, red lesions form in skin folds), and erythrodermic psoriasis (widespread redness, severe itching, and pain).

Regardless of type, psoriasis usually causes discomfort. The skin often itches, and it may crack and bleed. In severe cases, the itching and discomfort may keep a person awake at night, and the pain can make everyday tasks difficult.

Psoriasis is a chronic, meaning lifelong, condition because there is currently no cure. People often experience flares and remissions throughout their life. Controlling the signs and symptoms typically requires lifelong therapy.

Treatment depends on the severity and type of psoriasis. Some psoriasis is so mild that the person is unaware of the condition. A few develop such severe psoriasis that lesions cover most of the body and hospitalization is required. These represent the extremes. Most cases of psoriasis fall somewhere in between.

Who Gets Psoriasis
More than 4.5 million adults in the United States have been diagnosed with psoriasis, and approximately 150,000 new cases are diagnosed each year. An estimated 20% have moderate to severe psoriasis.

Psoriasis occurs about equally in males and females. Recent studies show that there may be an ethnic link. It seems that psoriasis is most common in Caucasians and slightly less common in African Americans. Worldwide, psoriasis is most common in Scandinavia and other parts of northern Europe. It appears to be far less common among Asians and is rare in Native Americans.

There also is a genetic component associated with psoriasis. Approximately one-third of people who develop psoriasis have at least one family member with the condition.

Research shows that the signs and symptoms of psoriasis usually appear between 15 and 35 years of age. About 75% develop psoriasis before age 40. However, it is possible to develop psoriasis at any age. After age 40, a peak onset period occurs between 50 and 60 years of age.

About 1 in 10 people develop psoriasis during childhood, and psoriasis can begin in infancy. The earlier the psoriasis appears, the more likely it is to be widespread and recurrent.

Psoriatic arthritis develops in roughly one million people across the United States, and 5% to 10% experience some disability. Psoriatic arthritis usually first appears between 30 and 50 years of age — often months to years after skin lesions first occur. However, not everyone who develops psoriatic arthritis has psoriasis. About 30% of people who get psoriatic arthritis never develop the skin condition.

Causes
Psoriasis may be one of the oldest recorded skin conditions. It was probably first described around 35 AD. Some evidence indicates an even earlier date. Yet, until recently, little was known about psoriasis.

While scientists still do not fully know what causes psoriasis, research has significantly advanced our understanding. One important breakthrough began with the discovery that kidney-transplant recipients who had psoriasis experienced clearing when taking cyclosporine. Since cyclosporine is a potent immunosuppressive medication, this indicates that the immune system is involved.

Immune Mediated. Researchers now believe that psoriasis is an immune-mediated condition. This means the condition is caused by faulty signals in the body’s immune system. It is believed that psoriasis develops when the immune system tells the body to over-react and accelerate the growth of skin cells. Normally, skin cells mature and are shed from the skin’s surface every 28 to 30 days. When psoriasis develops, the skin cells mature in 3 to 6 days and move to the skin surface. Instead of being shed, the skin cells pile up, causing the visible lesions.

Genes. Researchers have identified genes that cause psoriasis. These genes determine how a person’s immune system reacts. These genes can cause psoriasis or another immune-mediated condition, such as rheumatoid arthritis or type 1 diabetes. The risk of developing psoriasis or another immune-mediated condition, especially diabetes or Crohn’s disease, increases when a close blood relative has psoriasis.

Family History. Some people who have a family history of psoriasis never develop this condition. Research indicates that a “trigger” is needed. Stress, skin injuries, a strep infection, certain medications, and sunburn are some of the known potential triggers. Medications that can trigger psoriasis are anti-malarial drugs, beta-blockers (medication used to treat high blood pressure and heart conditions), and lithium. Dermatologists have seen psoriasis suddenly appear after a person takes one of these medications, gets a strep infection, or experiences another trigger.

Psoriasis research continues to accelerate at a rapid pace and will continue to advance our knowledge of what causes psoriasis.

Quality of Life
All types of psoriasis, ranging from mild to severe, can affect a person’s quality of life. Living with this lifelong condition can be physically and emotionally challenging.

Itching, soreness, and cracked and bleeding skin are common. Nail psoriasis can be painful. Even the simple act of squeezing a tube of toothpaste can hurt. One woman described her psoriasis as feeling like “a bad sunburn that won’t go away.”

Several studies have shown that people often feel frustrated. In some cases, psoriasis limits activities and makes it difficult to perform job responsibilities. The National Psoriasis Foundation reports that 56 million work hours are lost each year by those who have psoriasis. Additionally, a survey conducted by the National Psoriasis Foundation in 2002 indicates that 26% of people living with moderate to severe psoriasis have been forced to change or discontinue their normal daily activities.

Studies also have shown that stress, anxiety, loneliness, and low self-esteem are part of daily life for people living with psoriasis. One study found that thoughts of suicide are three times higher for psoriatics than the general population.

Embarrassment is another common feeling. Imagine getting your hair cut and noticing that the stylist or barber is visibly uncomfortable. What if you extended your hand to someone and the person recoiled? How would you feel if you spent most of your life trying to hide your skin?

Treatment Advances Improve Outlook
With the emergence of several new therapies, including the biologic agents, more people are experiencing substantial improvements and reporting a greatly improved quality of life.

References:
American Academy of Dermatology. “American Academy of Dermatology’s Psoriasis Public Awareness Campaign Provides Latest Information About this Skin Condition.” Available at: http://www.newswire1.net/NW2004/C_AAD_CH/111504/index.html. Accessed April 26, 2005.

American Academy of Dermatology. Psoriasis. Available at: http://www.aad.org/public/Publications/pamphlets/Psoriasis.htm. Accessed April 26, 2005.

Bowcock, A et al. “Genetics of psoriasis: The potential impact on new therapies.” Journal of the American Academy of Dermatology. 2003 August;49(2):S51-6.

Gupta MA et al. “Suicidal ideation in psoriasis.” International Journal of Dermatology. 1993 March;32(3):188-90

Holsinger, L. “A battle with my skin.” Journal of the American Academy of Dermatology. 2004 July;51(1)S41-42.

Hurley, HJ. “Papulosquamous Eruptions and Exfoliative Dermatitis” in Dermatology. Philadelphia, PA: W.B. Saunders Company; 1975.

Lebwohl, M. “Innovations in the treatment of psoriasis.” Journal of the American Academy of Dermatology. 2004 July;51(1)S40-41.

The Lewin Group, Inc. The Burden of Skin Diseases. Prepared for the Society for Investigative Dermatology and the American Academy of Dermatology Association. 2005. Available at: http://www.newswire1.net/NW2005/C_AAD_CH/AAD3001388_040605/assets/
downloads/printfriendlyskin.pdf. Accessed June 21, 2005.

National Psoriasis Foundation. Psoriasis and Psoriatic Arthritis: Treatment Guide for the Health Insurance Industry. 2004.