Psoriasis | Causes of Psoriasis

Although scientists have not yet identified the exact cause or causes of psoriasis, they do know that psoriasis begins in the body’s immune system. Specifically, it is triggered when a certain type of T cell malfunctions and reproduces uncontrollably. These malfunctioning T cells travel to the surface of the skin, and start an inflammatory reaction in which skin cells multiply 7 to 12 times faster than normal. The end result is the formation of psoriatic plaques. Biologic treatments for psoriasis fight back by reaching far beneath the skin to halt this psoriatic process exactly where it starts—in the immune system.

Psoriasis tends to run in families, indicating that there is a genetic component of the disease. Statistically speaking, 30 to 50 percent of people with psoriasis have relatives who also have psoriasis. A child born to two parents who have psoriasis is more likely to develop it than if one parent has psoriasis. The risk also is high--but not 100 percent--if an identical twin has psoriasis, which suggests that genes alone are not responsible.

What else plays a role in developing psoriasis? Environmental factors are thought to trigger psoriasis in people who have a genetic tendency toward the disease. The environment also may cause flare-ups, which are the periods when existing skin plaques worsen temporarily. Flares are common in psoriasis, as are remissions, when the disease appears to get better suddenly.

Several triggers have been linked to psoriasis flares, including:

Damage to the skin -- Injury, frequent rubbing or scratching the skin may cause plaques to worsen in a process known as Koebner’s phenomenon.

Infections -- Streptococcal throat infections (strep throat) may trigger guttate psoriasis, a form of psoriasis that usually occurs in childhood.

Medications -- Drugs linked to a worsening of psoriasis include lithium, drugs used to treat malaria, beta-blockers, non-steroidal anti-inflammatory drugs, and oral steroids.

Stress -- Some studies have linked stress to flares, which can occur as much as one month after the stressful event.

Alcohol and smoking -- Drinking and smoking are not considered major risk factors for developing psoriasis, but they may trigger flares, especially alcohol consumption in men and smoking in women.

Diet -- While nutrition may play a role in psoriasis, the scientific basis for improving symptoms with diet has not been established.

Climate -- Psoriasis is often better in the summer months, when the skin is exposed to sunshine, and worse during the cloudy winter months. Winter may be a good time for a vacation to a sunny spot!