Almost as common as the cold and as hard to find a cure for
"In psoriasis, activated T cells accumulate in the outer layer (epidermis) and inner layer (dermis) of the skin, where they reproduce at a rapid rate due to chemicals called cytokines, such as TNF-alpha, which send a fault message to the skin..."— Psoriasis: Everything You Need to Know, Richard Langley MD
Psoriasis affects about one person in 50 -- more than a million in the UK alone. Its name has a Greek root -- pura, meaning itch. But itching does not always accompany psoriasis. Nevertheless for 1 to 2 per cent of the population, red and angry-looking lesions and silver scaly flakes are part of their lives. Medical science concentrates on management, of sometimes severe cases, while searching for a cure.
Psoriasis -- the more we know the sooner the cure
Greek physician Hippocrates first mentioned psoriasis in his 400 BC writings, lumping it with other skin conditions including leprosy. In 200 AD Galen, a Roman doctor used the words "psoriasis vulgaris" and from that time it became a catch-all to describe skin disorders.
Most patients have a relatively mild form of the disease. Dr Langley estimates 80 to 90 per cent of sufferers can control it with topical and over-the-counter applications. But at the higher end the silver scaly and red patches can cover most of the body and require hospitalisation. The associated psoriatic arthritis affects 5 per cent of skin psoriasis sufferers.
Modern science concentrates on the faulty immune system aspect – and the fact this encourages the skin to overproduce skin cells in affected areas. Alternative medicine takes the view psoriasis requires purification of the toxins in the body. The US-based National Psoriasis Foundation (NPF) encourages sufferers to try both types of treatment.
In less enlightened times, back to the Greeks and Romans, society considered psoriasis like leprosy, mange and vitiligo. It required sufferers to wear special clothing and warn others away with a bell. In the mid-18th century Viennese doctors realised psoriasis was different from leprosy and then came the 19th century Russian breakthrough mentioned earlier.
Even two hundred years ago scientists knew of the hereditary nature of psoriasis and they now attribute it to three factors; genetics, environmental factors and the immune system, says Dr Langley.
Treatments 100 years ago were mostly topical applications – dithranol, coal tar, salicylic acid and Dead Sea salt baths – combined with sunlight. The 1950s brought the combination of topical and systemic steroids and in the 1970s treatments expanded to include the psoralen and ultraviolet A (longer range) light combination. Topical vitamin D3, retinoids and cyclosporine became popular in the 1990s and in the 21st century the trend is toward using biological therapies and laser treatment, says Dr Langley.
Psoriasis comes in several forms.
• The previously described plaque variety affects mostly elbows, knees, scalp, back and lower buttocks
• Erythrodermic ( or exfoliative) psoriasis covers almost all the body, even inside the mouth and nose and can progress from plaque psoriasis in result from a sudden flare up and requires hospitalization.
• Inverse psoriasis is in the skin folds, either with plaque psoriasis or on its own.
• Guttate psoriasis often occurs in childhood after a strep throat infection. It is raised bumps, in contrast to plaque, and usually clears up completely.
• Psoriatic arthritis is inflammation of the joints, as opposed to the skin. It particularly affects the hands, wrists, ankles, feet, neck and back. Dr Langley estimates 15 to 30 per cent of psoriasis patients will develop the arthritic form.
• Psoriasis of the scalp gets to about 50 per cent of psoriasis sufferers, particularly on the hairline and behind the ears.
• Pustular psoriasis produces small blister-like area of non-infected pus on the skin.
The sun and light treatment
The sun’s ultraviolet (UV) rays quieten the faulty signals from the immune system, says Dr Langley. This accounts for psoriasis sufferers noticing an improvement in summer, even on unexposed areas, and the opposite in winter.
Phototherapy is exposure to the longer (UVA) or shorter (UVB) rays and can include taking light-sensitising drugs to increase the UV's effectiveness. Patients can take the treatments at an authorized clinic or at home. The UVB rays gives us a tan, or in excess, sunburn. They work better on psoriasis than UVA rays but do not penetrate as deeply as needed.
UVA does not work well by itself but with psoralen can provide a very effective treatment, known as PUVA (psoralen+UVA). Patients take the psoralen in a pill or ointment and must wear UV protection (full clothing and sunglasses) for 24 hours after treatment, because they are more susceptible to sunlight. Combining UVB and topical coal tar goes back to 1925, notes Dr Langley. This produces good results because the coal tar makes the skin more sensitive to UV light.
Topical and over-the-counter treatments account for most of the self-medicating among psoriasis sufferers. They can be creams, ointments, lotions, gels or even aerosols.
• Coal tar is one of the oldest remedies still in use, and one of the few remedies available to psoriasis patients before 1920. Along with the above forms it can be a bath solution or shampoo. It can make the skin more sensitive to ultraviolet light but be messy. The higher the concentration of tar the higher the potency but also the higher the carcinogenic possibility, notes author Lisa LeVan in "The Psoriasis Cure", although her theory is not scientifically conclusive.
• Topical steroid creams can bring the itch of psoriasis under control, says Dr Langley. They are the most commonly prescribed topical therapy and their potencies range from mild ( 0.5 per cent hydrocortisone), which is available over the counter to the super-potent ointments such as clobetasol propionate 0.05 per cent.
• Like coal tar, anthralin is very messy and has lost popularity for that reason. It comes in a range of potencies and some treatments centres may use it combination with UVB light. This is the Ingram Regimen – putting on anthralin before UVB light treatment.
• Vitamin D, which can slow the rate of skin cell multiplication, comes in the form of calcopotriol. It works well with the high-potency topical steroids, in severe cases.
Modern systemic treatments
A big leap forward to the cure for psoriasis was establishing its link with the immune system late last century, says Dr Langley. This gave rise to several systemic and biologic treatments. Systemic drugs are usually for medium to severe cases and work in conjunction with other therapies.
• Methotrexate works by reducing the rapid turnover of skin cells, says Dr Langley. It is also an anti-inflammatory on white blood cells. It can benefit sufferers of the all-covering erythrodermic as well as pustular psoriasis.
• Cyclosporine was originally given to organ transplant patients as an immune suppressant, so its application to psoriasis sufferers came by chance. Highly effective and quick acting, it works by inhibiting activation of the T lymphocyte cells.
• Soriatane is a first-line systemic drug that works for chronic forms of pustular psoriasis, in patients who will not be bearing children at any stage. It does not work well on plaque psoriasis, according to the Archives of Dermatology.
• Humira may be used a first-line systemic drug for plaque psoriasis and has a lower rate of adverse effects compared with methotrexate, says the Archives of Dermatology.
• Enbrel – taken by sub-cutaneous injection twice a week at first and then weekly after three months, has had good results at trials with 75 per cent showing noticeable improvement.
Biologic drugs work by interfering with specific components of the autoimmune system, says Dr Langley. Biologics are often naturally occurring substances and are so-called “designer” drugs, he says.
• Stelara is injected. The first dose is 45mg under the skin, for patients under 100 kg. Heavier ones get twice the dose. The second is a month later. It compares favourably with Enbrel for effectiveness and works well with chronic plaque psoriasis, notes the Archives of Dermatology.
• Alefacept is a fully human biologic agent that works on the activated T-cells, reducing the number in circulation. Administration is via a single intra-muscular injection once a week for 12 weeks.
• Efalizumab is another injected biologic and works by preventing the activation of T-cells and stopping them entering the skin. In trials it has shown rapid clearing but psoriasis returned after two when the injections stopped.
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