Psoriasis

Psoriasis is a condition whose main symptom is gray or silvery flaky patches on the skin which are red and inflamed underneath. In the United States, it affects 2 to 2.6 percent of the population, or between 5.8 and 7.5 million people. Commonly affected areas include the scalp, elbows, knees, arms, stomach and back. Psoriasis is autoimmune in origin, and is not contagious. Around a quarter of people with psoriasis also suffer from psoriatic arthritis, which is similar to rheumatoid arthritis in its effects. Psoriasis was first given that name in complete differentiation from other skin conditions by the Austrian dermatologist Ferdinand von Hebra in 1841, although there are what are believed to be descriptions of the disease in sources going back to ancient Roman and possibly even biblical times.

Effect on the quality of life
Individuals with psoriasis may experience significant physical discomfort and some disability. Itching and pain can interfere with basic functions, such as self-care, walking, and sleep. Plaques on hands and feet can prevent individuals from working at certain occupations, playing some sports, and caring for family members or a home. The frequency of medical care is costly and can interfere with an employment or school schedule. People with moderate to severe psoriasis may feel self-conscious about their appearance and have a poor self-image that stems from fear of public rejection and psychosexual concerns. Psychological distress can lead to significant depression and social isolation.

Causes
Psoriasis is driven by the immune system, especially involving a type of white blood cell called a T cell. Normally, T cells help protect the body against infection and disease. T cells help create scabs over wounds. In the case of psoriasis, T cells are put into action by mistake and become so active that they trigger other immune responses, which lead to inflammation and to rapid turnover of skin cells. Most recently, the natural or innate immune system has been found to be highly implicated. Non-specific natural responses of the skin immune system, and virtually every subsystem of that, are activated in psoriasis. Epidermal cells up on the surface of the skin, forming itchy patches or plaques. The first outbreak of psoriasis is sometimes triggered by emotional or mental stress or physical skin injury, but heredity is a major factor as well. In about one-third of the cases, there is a family history of psoriasis. Researchers have studied a large number of families affected by psoriasis and identified genes linked to the disease. (Genes govern every bodily function and determine the inherited traits passed from parent to child.) People with psoriasis may notice that there are times when their skin worsens, then improves. Conditions that may cause flareups include infections, stress, and changes in climate that dry the skin. Also, certain medicines, including Lithium salt and beta blockers, which are prescribed for high blood pressure, may trigger an outbreak or worsen the disease. Other autoimmune diseases such as HIV/AIDS may significantly worsen the symptoms of psoriasis. Alcohol consumption and obesity may also worsen the condition.

Treatment
Specialist dermatologists generally treat psoriasis in steps based on the severity of the disease, size of the areas involved, type of psoriasis, and the patient's response to initial treatments. This is sometimes called the "1-2-3" approach. In step 1, medicines are applied to the skin (topical treatment). Step 2 uses ultraviolet light treatments (phototherapy). Step 3 involves taking medicines by mouth or injection that treat the whole immune system (called systemic therapy).

Over time, affected skin can become resistant to treatment, especially when topical corticosteroids are used. Also, a treatment that works very well in one person may have little effect in another. Thus, doctors often use a trial-and-error approach to find a treatment that works, and they may switch treatments periodically (for example, every 12 to 24 months) if a treatment does not work or if adverse reactions occur.

Topical treatment
Treatments applied directly to the skin may improve its condition. Doctors find that some patients respond well to ointment or cream forms of corticosteroids, vitamin D3, retinoids, coal tar, or anthralin. Bath solutions and moisturizers may be soothing, but they are seldom strong enough to improve the condition of the skin. Therefore, they usually are combined with stronger remedies.