Psoriasis causes
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [5]
Overview
The cause of psoriasis is not known, but it is believed to have a genetic component. Several factors are thought to aggravate psoriasis.
Causes
Common Causes
The cause of psoriasis is not fully understood, but there is some idea that common causes of psoriasis include stress, excessive alcohol consumption, and smoking.
Psoriasis is a fairly idiosyncratic disease. The majority of people's experience of psoriasis is one in which it may worsen or improve for no apparent reason. Studies of the factors associated with psoriasis tend to be based on small (usually hospital based) samples of individuals. These studies tend to suffer from representative issues, and an inability to tease out causal associations in the face of other (possibly unknown) intervening factors. Conflicting findings are often reported. Nevertheless, the first outbreak is sometimes reported following stress (physical and mental), skin injury, and streptococcal infection. Conditions that have been reported as accompanying a worsening of the disease include infections, stress, and changes in season and climate. Certain medicines, including lithium salt and beta blockers, have been reported to trigger or aggravate the disease. Excessive alcohol consumption, smoking and obesity may exacerbate psoriasis or make the management of the condition difficult.[1][2]
Individuals suffering from the advanced effects of the Human immunodeficiency virus, or HIV, often exhibit psoriasis.[3] This presents a paradox to researchers as traditional therapies that reduce T-cell counts generally cause psoriasis to improve. Yet, as CD4-T-cell counts decrease with the progression of HIV, psoriasis worsens.[4] In addition, HIV is typically characterized by a strong Th2 cytokine profile, whereas psoriasis vulgaris is characterized by a strong Th1 secretion pattern.[5] It's hypothesized that the diminished CD4-T-Cell presence causes an over-activation of CD8-T-Cells, which are responsible for the exacerbation of psoriasis in HIV positive patients. It is important to remember that most individuals with psoriasis are otherwise healthy and the presence of HIV accounts for less than 1% of cases. The prevalence of psoriasis in the HIV positive population ranges from 1 to 6 percent, which is about 3 times higher than the normal population.[6]
Psoriasis occurs more likely in dry skin than oily or well-moisturized skin, and specifically after an external skin injury such as a scratch or cut. This is believed to be caused by an infection, in which the infecting organism thrives under dry skin conditions with minimal skin oil, which otherwise protects skin from infections. The case for psoriasis is opposite to the case of athlete's foot, which occurs because of a fungus infection under wet conditions as opposed to dry in psoriasis. This infection induces inflammation, which causes the symptoms commonly associated with psoriasis, such as itching and rapid skin turnover, and leads to drier skin as the infecting organism absorbs the moisture that would otherwise go to the skin. To prevent dry skin and reduce psoriasis symptoms, it is advised to not use shower scrubs, as they not only damage skin by leaving tiny scratches, they also scrape off the naturally occurring skin oil. Additionally, moisturizers can be applied to moisturize the skin, and lotions used to promote skin oil gland functions.
References
- ↑ [1] Psoriasis Triggers at Psoriasis Net. SkinCarePhysicians.com 9-28-05. American Academy of Dermatology, 2008.
- ↑ Behnam SM, Behnam SE, Koo JY (2005). "Smoking and psoriasis". Skinmed. 4 (3): 174–6. PMID 15891254.
- ↑ [2][3] Fife, Jeffes, Koo, Waller. Unraveling the Paradoxes of HIV-associated Psoriasis: A Review of T-cell Subsets and Cytokine Profiles. 5-18-07. Retrieved 5-13-08.
- ↑ Ortonne JP, Lebwohl M, Em Griffiths C (2003). "Alefacept-induced decreases in circulating blood lymphocyte counts correlate with clinical response in patients with chronic plaque psoriasis". Eur J Dermatol. 13 (2): 117–23. PMID 12695125.
- ↑ Austin LM, Ozawa M, Kikuchi T, Walters IB, Krueger JG (1999). "The majority of epidermal T cells in Psoriasis vulgaris lesions can produce type 1 cytokines, interferon-gamma, interleukin-2, and tumor necrosis factor-alpha, defining TC1 (cytotoxic T lymphocyte) and TH1 effector populations: a type 1 differentiation bias is also measured in circulating blood T cells in psoriatic patients". J. Invest. Dermatol. 113 (5): 752–9. doi:10.1046/j.1523-1747.1999.00749.x. PMID 10571730. Unknown parameter
|month=ignored (help) - ↑ [4] A Case Report of Severe Psoriasis in a Patient with AIDS: The Role of the HIV Virus and the Therapeutic Challenges Involved. Vol: 13 No 2, 2002. National Skin Center. Retrieved 05-13-08.