What Causes Psoriasis?

The exact cause of psoriasis isn't known, but scientists have theories that tie psoriasis to a genetic factor. Approximately one in three people that have the condition have a history of the disease within their own family. They have a close blood relative that also has psoriasis, making researchers hypothesize that there is a genetic component to the ailment. There have been genes that are associated with psoriasis isolated, but the fact that some people carry this very gene and never show any symptoms of psoriasis means there is more to it than what is now understood.

The mechanism that causes psoriasis makes it considered what is called an immune-mediated condition. This means that the person with psoriasis has an immune system that somehow malfunctions, precipitating the abnormal growth of skin cells. In most people skin cells take almost a full month to grow and replace dead and old skin cells on the surface of the skin. But an immune-system disorder makes the skin cells in someone with psoriasis mature in as little as three days. They then make their way to the surface of the skin where they build up into thick areas that turn red and develop scales.

The actual culprit behind psoriasis is a kind of white blood cell known as a T lymphocyte. These "T cells," as they are called, are supposed to make their way through an individual's body where their proper function is to find foreign substances that are capable of causing infections. Such substances as viruses and bacteria are attacked by these T cells and destroyed before they can do the body any harm. Somehow, in people with psoriasis, the T cells mistakenly launch their attack against perfectly healthy skin cells.

When the hyperactive T cells attack normal skin cells, they set off immune responses that result in the manufacture of healthy skin cells as well as even more T cells. This starts a chain-reaction cycle, which in the end causes most of the brand-new skin cells to migrate upward to the skin's surface. Once there, the dead skin cells combine with the new ones along with the white blood cells to form scaly patches that are characteristic of psoriasis.

The reason behind the malfunctioning T cells isn't at all clear, but there are certain things that trigger them into action. Bouts of psoriasis will begin or get even worse due to these triggers, which can then be identified and avoided in the future in some instances. Common psoriasis triggers include types of infections such as strep throat or injuries to a person's skin like sunburn or a cut. Psoriasis can be triggered by emotions such as stress and by exposure of the skin to cold weather. Alcohol and smoking have been linked to making psoriasis worse, and there are medications such as those used to battle high blood pressure that have been identified as psoriasis triggers.