Causes and Risks Factors of Plaque Psoriasis

A Complex Interaction Between Genetics and Your Environment

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 or behaviors can either trigger symptoms or increase the frequency or severity of an outbreak. These "triggers" range from infections and obesity to medications and stress.

plaque psoriasis risk factors
© Verywell, 2018 


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

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 for psoriasis, 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 a symptomatic episode, known as a flare.


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 a defining factor for the activation of psoriasis, whether it is caused a chronic infection like HIV or diabetes or an acute one like bronchitis, strep throat, or the flu.

By contrast, treating an infection can often alleviate symptoms. By way of example, a 2013 study from Poland reported that statin drugs reduced the severity of psoriasis in people with chronic heart disease by helping alleviate the underlying inflammation. The same appears to be true when antiretroviral drugs are used to treat HIV.

Skin Trauma

Skin trauma can also cause plaque psoriasis symptoms, commonly referred to as the Koebner phenomenon. (This response is seen with other skin conditions such as warts, lichen planus, and molluscum contagiosum.) As many as one in four people with psoriasis experience this phenomenon, 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 suddenly and inexplicably become the primary site of a psoriasis flare.


Certain medications are known to trigger psoriasis symptoms. They may not affect all people with psoriasis in the same way or cause any symptoms at all. The drugs most commonly cited include:

In addition, the sudden 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.

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


A 2014 study from the University of California, Davis reported 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 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 on the surface of cells that the immune system recognizes as harmful and attacks. Others have suggested that smoking simply triggers or accelerates the autoimmune response.

The researchers 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.


Stress has a cause-and-effect relationship with psoriasis. On the one hand, stress can trigger symptoms of the disease, while, on the other, symptoms can trigger stress. In the same way that the body sends out inflammatory signals to help heal a wound, psychological stress can trigger an inflammatory response that worsens rather than improves 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 the appropriate medical treatment, including psychotherapy and the use of antidepressants or anxiolytic (anti-anxiety) drugs.


Obesity can often give rise to the formation of plaques within folds of skin. While the exact cause of this is unclear, a 2012 study in Nutrition & Diabetes suggests that the excessive accumulation of fat increases the production of inflammatory proteins known as cytokines.

Cytokines not only increase inflammation, making symptoms worse, but also 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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