Normally, skin replaces itself a cell at a time. As a new cell grows and moves toward the surface, an old one dies and that’s where lay the causes of psoriasis.
With psoriasis, the code regulating the replacement of skin cells in an orderly fashion is overwritten by the immune system. T-cells, instead of attacking bacteria or virus, attack healthy skin cells. The body’s reaction is to produce an abundance of new cells, which move to the upper layer of skin too rapidly, creating the unnatural thickening, reddening, and scaliness of the skin that doctors call psoriasis.
There are eight distinct forms of psoriasis, with the most common form “plague psoriasis” covering 80 percent of all psoriasis cases. Researchers have identified at least part of this psoriasis problem as genetic. The balance of the problem, though, is likely environmental, ranging from normal stressors like cold air and sunlight to abnormal impacts, as from smoking and certain pharmaceuticals and drugs.
Genetically speaking, as many as 36 separate genes have been identified as causing psoriasis. Of these, some are “crossover” genes that also contribute to Crohn’s disease and celiac disease (both more common in people with psoriasis). Unfortunately, these 36 represent only 22 percent of an individual’s risk for psoriasis, so the genetic component of research into psoriasis is literally in its infancy.
In fact, 10 percent of the population shares these psoriatic genes. Only 3 percent actually get psoriasis, and this average increases the farther one lives from the equator. Combine the right number and location of psoriatic genes with environmental factors (family history, frequent bacterial or viral infections, stress, heavy alcohol use), and the result is psoriasis. Add a dose of lithium, beta-blockers, iodine compounds, or antimalarial drugs all prescription medications and psoriasis springs full-blown.
Researchers have also targeted causes like skin injury a puncture wound, a deep scrape, even a bad sunburn can cause psoriasis, according to the Koebner phenomenon. Examination of the available data also suggests that as many as 30 percent of individuals with psoriasis who sustain a bone injury may go on to develop psoriatic arthritis.