Causes and Risks Factors of Plaque Psoriasis

A Complex Interaction Between Genetics and Your Environment

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As an autoimmune disorder, plaque psoriasis remains something of a mystery in how it causes disease. While genetics play a significant role, other factors are believed to contribute. What we do know is that certain conditions and behaviors can either trigger symptoms of psoriasis or increase the frequency or severity of an outbreak. They range from infections to obesity, medications to stress.

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© Verywell, 2018 


Family history is the strongest risk factor for developing plaque psoriasis. In fact, around a third of the people affected by psoriasis will report having another family member with the disease. The risk of psoriasis seems all the more likely if both parents have it.

While scientists have yet to establish how the genetics work, they have identified nine locations on a gene associated with psoriasis symptoms, which they have labeled PSORS1 through PSORS9. Of these, around 35 percent to 50 percent of people with plaque psoriasis will have a chromosomal mutation of PSORS1.

It is hoped that by breaking the genetic code, scientists may one day be able to "switch off" or repair the mutations associated with the disease.

Common Triggers

While plaque psoriasis can affect anyone, there are a number of factors that appear to increase the likelihood of symptoms (also known as flares).


Both acute and chronic infections can trigger psoriasis symptoms. We see this especially with HIV, a chronic disease associated with persistent inflammation. While the rate of psoriasis is more or less the same as the general population, the severity of the disease is far worse when HIV is involved. Immune suppression appears to be the central factor, whether it is caused by HIV or an acute infection like bronchitis, strep throat, or the flu.

By contrast, treating an infection can often alleviate symptoms. Studies have shown, for example, that statin drugs can reduce the severity of psoriasis common in people with chronic heart disease. The same appears to be true when antiretroviral drugs are used in people with HIV.

Skin Trauma

Skin trauma can also cause plaque psoriasis symptoms, commonly referred to as the Koebner phenomenon. This response is also seen with others conditions such as warts, lichen planus, and molluscum contagiosum.

As many as one in four people with psoriasis experience this, triggered by everything from sunburns and insect bites to skin allergies and needle pricks. Even older skin injuries, such as a surgical wound or tattoo, can become the primary site of a psoriasis flare.


Certain medications are known to trigger psoriasis symptoms. They do not affect all people in the same way and may not cause symptoms at all. However, the drugs most commonly cited include:

  • Lithium
  • Beta-blockers
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Anti-malaria drugs
  • Calcium channel blockers
  • Lipid-lowering medications

In addition, the immediate termination of topical corticosteroids used to treat psoriasis can have a "rebound" effect and lead to a severe flare. For this reason, corticosteroids should always be tapered off gradually, under the guidance of a doctor, if the drug is no longer needed.

Plaque Psoriasis Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

Lifestyle Risk Factors

Insofar as lifestyle risks are concerned, there are three that are inextricably linked to the plaque psoriasis: stress, smoking, and obesity.


Stress has a cause-and-effect relationship to psoriasis. On the one hand, stress can trigger symptoms, while, other the other, symptoms can trigger stress.

In the same way that the body sends out inflammatory signals to heal a wound, psychological stress can trigger an inflammatory response that has an inverse effect, worsening rather than improving the condition.

This is especially worrisome since chronic psoriasis is associated with high rates of depression and anxiety. In some cases, the vicious cycle can only be broken with proper medical treatment, including psychotherapy and the appropriate use of antidepressant or anti-anxiety drugs.


Recent studies have shown that people who smoke more than a pack of cigarettes per day are twice as likely to have severe psoriasis than those who smoke 10 cigarettes or less daily.

Scientists are not sure why this is but believe that smoking may increase the number of autoantigens in the outermost layer of skin (known as the epidermis). These are the proteins that the immune system targets for an autoimmune attack. Others have suggested that smoking simply triggers or accelerates the autoimmune response.

The same research has also concluded that women who smoke are at greater risk of severe psoriasis than men. The number of years a person has smoked also contributes.


Obesity can often give rise to the formation of plaques within folds of skin. While the exact cause of this is unclear, research suggests that the excessive accumulation of fat increases the production of inflammatory proteins known as cytokines.

Cytokines not only increase the overall inflammation, making the symptoms worse, but promote the formation of plaques in areas where fat volumes are greatest (namely, the skin folds).

The association is further evidenced by the relationship between obesity, diabetes, and psoriasis. Whereas obesity can quadruple a person's risk of type 2 diabetes, diabetes can increase the risk and severity of plaque psoriasis by 27 percent.

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