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Psoriasis
 

Psoriasis Introduction

:psoriasis.jpg Psoriasis is a noncontagious inflammatory skin condition. It is often defined as a common chronic, or recurrent disease. Psoriasis is characterized by dry, well circumscribed, silvery scaling papules and plaques of various sizes. [1] Approximately 3 million Americans are affected (8 out of every 10,000 people). Psoriasis generally appears between the ages of 15 to 35 years old. Caucasians are at the greatest risk, as whites are diagnosed more frequently than African-Americans. Men and women are equally affected. There is also a strong genetic predisposition for the disease.

Although the actual cause of psoriasis is unknown, the pathophysiology is well documented. Normally, skin cells turn over in about a month. Cells from the lowest layer of skin move to the surface, primarily the keratinocytes. However, in persons with psoriasis this process takes only three or four days. The keratinocyte’s cell cycle is altered, thereby changing the balance and homeostasis of certain cell signals, specifically cAMP (cyclic adenosine monophosphate) and cGMP (cyclic guanidine monophosphate). Psoriasis causes cGMP signals to elevate and cAMP to decrease. This leads to a defining characteristic is psoriasis patients-increased cell numbers. [2] Clinically, inflammation of the dermis and a build up of dead skin cells which form thick scales, is also observed.

Proposed causes of psoriasis include elevated cGMP due to oxidative stress. Oxidative stress can be the result of alcohol consumption, food allergies, stress, and infection. Incomplete protein digestion, bowel toxemia, and liver function have been linked to psoriasis as well. These possible causes are, more than likely, linked to the abovementioned connection of oxidative stress and altered cGMP/cAMP levels. [3]

Psoriasis Symptoms

The onset of psoriasis can be gradual or sudden, but usually appears after a number of months. Patients complain of itchy skin patches that may be dry and red, and then become covered with silver scales. Affected patches of skin are raised and have a red border. The scales can crack and bleed. Commonly affected boy locations include; extensor surface of elbows and knees, the trunk, scalp, buttocks, sacral area, hands, and occasionally nails (which may be psoriatic arthritis if the patient also suffers from arthritic symptoms). [1]

The course of psoriasis is generally characterized by chronic remissions, recurrences and/or possibly exacerbations. Almost 50% of patients report that a stressful event occurred within one month of the first episode. [4] Once the first episode has occurred, some factors may then precipitate future flare-ups, such as; severe sunburn, viremia, group A β-hemolytic streptococcal upper respiratory infection, allergic drug reactions, and topical and systemic drugs such as β–blockers and lithium.

Other conditions that may mimic psoriasis include; atopic dermatitis, lichen simplex chronicus, seborrheic dermatitis, secondary or tertiary syphilis, Reiter’s syndrome, candidiasis, lichen planus, pityriasis rosea and tinea corporis.

Psoriasis Treatment

Psoriasis is generally not life threatening. It is considered important to control psoriasis on both physical and psychological levels. This condition often has a dramatic impact on one’s self-esteem. Depending on the extent and severity of the plaques, various approaches may be utilized.

Conventional Psoriasis Treatment:

Treatments can be categorized into lubricating creams, topical corticosteroids, light therapy, immune suppressants, and other topical creams. [1]

Lubricating creams may include commercial moisturizers [Neutrogena], hydrogenated oils, and white petroleum [Vaseline]. These are applied after bathing to prevent further drying, which can cause the skin to crack.

Specific topical creams include; Anthralin [Drithocreme, Micanol], which inhibits cell proliferation; a retinoid gel called tazarotene [Tazorac], which cannot be used by pregnant women or those who are trying to conceive due to possible birth defects; coal tar preparations that decrease cell proliferation (often smell bad and stain clothing); and calipotrieine [Donovex], which is a Vitamin D derivative that also slows down cell growth. Topical corticosteroids are also used in conjunction with these topical preparations. These combination creams, or ointments, are considered more effective when covered with occlusive dressings or when incorporated into flurandrenolide tape. The potency and type of topical preparation is selected based on severity of lesions.

Immune suppressants such as oral methotrexate are reserved for the most severe and disabling cases. Methotrexate appears to interfere with the rapid proliferation of keritninocytes, however, it also effects many other organ functions and administration must be closely monitored. Cyclosporines are also used for unresponsive and severe cases, but also have the same deleterious effects as methotrexate.

PUVA [psoralen-ultraviolet light therapy] is useful for cases with extensive lesions, covering large regions of the skin surface. Patients usually receive an oral dose of methoxsalen, followed by long wave UV therapy. This procedure may increase the incidence of UV-induced skin cancer with repeated exposures.

Supplements helpful for Psoriasis

Essential fatty acids

Certain essential fatty acids found in fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have reduced the severity of psoriasis in a number of controlled trials. [6, 7] Essential fatty acids are thought to exert effects via the inflammation cascade, which can modulate many dysfunctions that lead to or control various chronic disease states.

Fumaric acid

Fumaric acid esters have been used effectively in cases of severe and widespread psoriasis. [8] Because of the increased incidence of side effects like nausea, skin flushing, and kidney and liver abnormalities, this therapy is reserved only for patients with severe cases, when other therapies have been ineffective.

Capsaicin

The primary compound with the greatest activity in hot peppers is capsaicin. Capsaicin has been shown to deplete substance P, which is associated with pain perception. A double blind trial demonstrated the topical application of capsaicin cream, and showed significant improvements in psoriasis lesions and improvements of the adverse symptoms associated with the condition, namely, itching. [9]

Vitamin D

Studies have shown both topical and oral doses of vitamin D to be effective in treating psoriasis. With topical applications of 1,25-dihydroxycholecalciferol, the majority of patients noticed excellent or moderate improvements in their psoriasis symptoms. [10] Oral doses of 1,25-dihydroxycholecalciferol have even demonstrated complete remission in some patients. [11]

Glycyrrhiza glabra

One of the key constituents of licorice is glycyrrhetinic acid [GA]. When applied topically, GA has a similar anti-inflammatory effect as topical hydrocortisone. [12]

Aloe vera

Topically applied aloe extract, included in a hydrophilic cream, was more effective than placebo. Furthermore, it did not show toxicity or any other objective side-effects in a placebo controlled double-blind study. [13]

References

1. Merck Manual of Diagnosis. Merck Research Laboratories, Whitehouse Station, NY, 1999: 512-514.

2. Voorhees J and Duell E. Imbalanced Cyclic AMP-Cyclic GMP Levels in Psoriasis. Adv Cyc Nucl Res 1975;5:755-757.

3. Murray MT and Pizzorno JE. Encyclopedia of Natural Medicine, 2nd Ed. Prima Publishing, Rocklin, CA 1998:764-765

4. Seville RH. Stress and Psoriasis: the Importance of Insight and Empathy in Prognosis. J Amer Acad Derm 1989;20(1):97-100.

5. Muller-Limmroth W, FRohlich HH. Effect of various phytotherapeutic expectorants on mucociliary transport. Fortschritte der Medizin 1980; 98(3):95-101.

6. Bittner SB, et al. A double blind randomized placebo controlled trial of fish oil in psoriasis. Lancet 1988;1:378-380.

7. Kojima T, et al. Long-term administration of highly purified eicosapentaenoic acid provides improvement in psoriasis. Dermatoligica 1991;182:225-230.

8. Nieboer C, et al. Systemic therapy with fumaric acid derivatives: new possibilities in the treatment of psoriasis. J Am Acad Dermatol 1989;20:601-608.

9. Ellis CN, et al. A double-blind evaluation of topical capsaicin in pruritic psoriasis. J Am Acad Dermatol 1993;29:438-442.

10. Perez A, et al. Efficacy and safety of topical calcitriol (1,25-dihydroxycholecalciferol) for the treatment of psoriasis. Br J Dermatol 1996;134:238-246.

11. S Takamoto, et al. Effect of 1-Alpha-Hydroxycholecalciferol on Psoriasis Vulgaris: A Pilot study. Calcif Tissue Int 1986;39:360-364.

12. Evans FQ. The rational Use of Glycyrrhetinic Acid in Dermatology. Br J Clin Pract 1958;12:269-279.

13. Syed TA, et al. Management of psoriasis with Aloe vera extract in a hydrophilic cream: a placebo-controlled, double-blind study. Trop Med Int Health. 1996;Aug 1(4):505-9.