The exact cause of psoriasis is not yet known, but scientists believe it has something to do with the immune system of T cells and other white blood cells called neutrophils. Whereas T cells normally defend against foreign objects in the body like viruses and bacteria, T cells in patients with psoriasis attack healthy skin cells by mistake, as if they are trying to heal a wound or fight an infection. These overactive T cells then trigger increased production of neutrophils and other white blood cells, which leads to many of the symptoms associated with psoriasis. What scientists don’t understand, however, is what causes these T cells to malfunction in the first place.
Scientists and doctors believe that two key factors are involved, the immune system and genetics. Psoriasis is an autoimmune disease, which means that the body attacks itself. In the case of psoriasis, the T cells mistakenly attack healthy skin cells, resulting in plaques and inflamed red areas of skin. As for genetics, it seems that some people inherit genes which make them more likely to develop psoriasis. Those with immediate family members who have psoriasis are at a much greater risk for developing the disease themselves. That said, only 2 to 3 percent of people with the gene will develop the condition. Nonetheless, a genetic predisposition combined with triggers can result in the development of psoriasis.
A flare-up of psoriasis typically starts with a trigger. The most common ones include stress, infections, injury to skin, smoking, heavy alcohol consumption, vitamin D deficiency, hormone changes, and certain medications. Infections include both skin infections and other infections, a very common one being strep throat. As for injury to the skin, this includes everything from cuts and scrapes to bug bites and severe sunburns. Smoking and alcohol are not only triggers, but can also worsen symptoms and make treatments less effective. Low levels of vitamin D can impact the body’s ability to keep the skin healthy. Hormone changes during puberty and menopause can trigger flare-ups, while pregnancy may make symptoms better or make them disappear completely. In terms of medications, antimalarial drugs and iodides, high blood pressure medications such as beta blockers, and lithium prescribed for bipolar disorder are all potential triggers.
Anyone can develop psoriasis, no matter their age, race, or gender, but there are certain risk factors that can increase the chances of developing the disease. These include family history, viral and bacterial infections, stress, obesity, and smoking. Starting with family history, having just one parent with psoriasis increases the chances of developing psoriasis, and having two parents with psoriasis increases the chances even more. As for viral and bacterial infections, people with HIV and children with recurrent infections are more likely to develop the disease. Stress impacts the immune system and is therefore often discussed in association with psoriasis. Obesity, on the other hand, creates more surface area and skinfolds for plaques to develop, so excess weight increases the risk as well. Lastly, smoking tobacco can increase both the risk and the severity of symptoms, and may also play a role in the initial onset of psoriasis.
Resources:
1) https://www.mayoclinic.org/diseases-conditions/psoriasis/symptoms-causes/syc-20355840
2) https://www.healthline.com/health/psoriasis
3) https://www.webmd.com/skin-problems-and-treatments/psoriasis/psoriasis-causes-triggers#1