Common Types of Psoriasis
Psoriasis is a lifelong disease that affects the skin. It is thought to be an autoimmune disease. Psoriasis is currently incurable, but treatments are available to control symptoms. There are five main types: plaque, guttate, inverse, pustular and erythrodermic. Of these, plaque psoriasis is by far the most common, affecting about 85 percent of people with the disease. Plaque psoriasis manifests as reddish to whitish scaly patches, often appearing on the skin of the knees, elbows, scalp and lower back. Raised, inflamed, silvery-white patches are called plaques. Guttate psoriasis is a less common variant of the disease, in which many small, round, red or pink spots form over large areas of the body. Inverse psoriasis is a form that features smooth reddish patches that often appear in folds of skin, such as under the arms, or between the thighs and groin.
What Causes Psoriasis?
Experts still debate the exact causes of psoriasis, but the disease clearly results from the excessive growth and reproduction of deep-layer skin cells called keratinocytes. According to a popular hypothesis, psoriasis is an autoimmune disease: The immune system mistakenly targets some of its own cells for attack. Here we see white blood cells (T-cells) migrate from the bloodstream to the epidermis of the skin, where they release inflammation-promoting proteins called cytokines. Among the most damaging of these is tumor necrosis factor-alpha (TNF-a). TNF-a triggers inflammation and promotes excessive growth and accumulation of skin cells, which die as they pile up on the surface, forming silvery plaques.
How Psoriasis Plaques Form
Tumor necrosis factor-alpha and other cytokines promote excessive skin cell production and ongoing inflammation. As cells die, they pile up at the surface, forming silvery-whitish plaques. Although flare-ups may improve, or worsen, for no apparent reason, episodes may be triggered by a number of factors, including: bacteria or viral infections (especially strep infections); dry air, or overly dry skin; injury to the skin, including cuts, burns, and insect bites; certain medications, including beta-blockers and lithium; physical or emotional stress; too little, or too much, sunlight (sunburn), too much alcohol; smoking (especially among women who also drink alcohol); and sleep loss.
Treating Mild Psoriasis With Topical Medications
Topical medications, such as corticosteroid creams, vitamin D analogs, retinoids, and calcineurin inhibitors, can reduce inflammation, helping slow excess cell growth. Treatments that combine a vitamin D analog (a synthetic form of vitamin D) with a corticosteroid are more effective than either ingredient alone. The old topical treatment, coal tar, can be effective, but it is notoriously smelly and may stain clothes and skin. Retinoids, derived from vitamin A, help normalize DNA activity in skin cells. While often effective, corticosteroid use is linked to a rebound effect, in which symptoms get worse after therapy is halted. Topical creams and ointments usually provide symptom relief for most patients with mild to moderate psoriasis. But they do not address the underlying causes of the disease.
Treating Psoriasis With UV Phototherapy
Phototherapy, or treatment with UV light, is among the most effective treatments for psoriasis. UV appears to help in a number of ways. Here, UV light suppresses the activity of immune cells that promote inflammation. UV exposure prompts the cells to release less tumor necrosis factor-alpha, which reduces inflammation. Some of the inflammation-promoting cells also die. Phototherapy can be done in your doctor’s office or at home. On a doctor’s recommendation, controlled exposure to sunlight can be practiced at home. Variations on standard UV therapy include use of the excimer laser and the pulsed dye laser. These therapies use lasers to precisely target plaques with specific wavelengths of UV-B light. With regular treatment sessions, the lasers gradually and safely limit the activity of overactive skin cells and/or inflammation-promoting T-cells.
Treating Psoriasis With Immune Suppressing Drugs
White blood cells communicate, propagating inflammation through the release of cytokines. Systemic immune suppressing agents interrupt this process. Agents include acitretin, methotrexate and cyclosporine. Although they can offer significant relief, studies show that these “non-biologic” agents are somewhat less effective than newer, more expensive “biologic” drugs. These immunosuppressant agents may also carry bigger long-term risks. Because they suppress the immune system in general, susceptibility to infections increases. Originally developed for cancer chemotherapy, methotrexate is used in much lower doses to treat psoriasis. As such, it is generally safe and well tolerated. However, some of the side effects associated with chemotherapy, such as nausea or hair loss, may still occur.
Treating Psoriasis With Biologics
Biologics are new drugs tailored to interfere with messenger chemicals, or to bind to specific receptors for those chemicals on immune system T-cells. Unlike topical agents, which only address symptoms, biologics target the underlying cause of psoriasis. By blocking receptors for cytokines such as tumor necrosis factor-alpha, biologics prevent the escalation of inflammation. Biologic drugs—so called because they consist of proteins derived from living cells—must be injected. They’re highly expensive, but experts note they are more effective, and have fewer side effects, than older systemic drugs. While systemic drugs dampen immune system activity generally, biologics target specific mediators of inflammation. Because they are so new, the long-term effects of using these agents remains uncertain. Examples include: adalimumab (Humira®), etanercept (Enbrel®), golimumab (Simponi®), infliximab (Remicade®), and ustekinumab (Stelara®).
More About Treatments for Psoriasis
Treating psoriasis typically requires several different approaches that may possibly include lifestyle changes, nutrition, and medication. The extent of treatment depends on the severity of the symptoms, a person’s age, overall health, and other factors. As there is no cure for psoriasis, doctors and dermatologists will often try several methods before finding the right one for a patient.