Causes and Risk Factors of Psoriasis

Show Article Table of Contents

psoriasis causes and risk factors

Illustration by Verywell

Although there are several different types of psoriasis, all are considered autoimmune disorders, meaning they develop when the body's immune system turns on itself and attacks healthy tissue—in this case, skin—in much the same way it would a real threat, such as bacteria or a virus. Researchers don't understand psoriasis completely, but it is believed to be a genetically-driven disorder that can be stimulated or exacerbated by factors such as weather, injury, illness, or stress.

Causes

According to the National Psoriasis Foundation (NPF), inflammation is the most likely mechanism behind the development of psoriasis.

Inflammation begins when a type of white blood cell called a T cell detects the presence of something harmful to the body, such as a virus or bacterium. In defense, the T cell triggers the production of a cytokine—a type of protein—called tumor necrosis factor, or TNF, which is manufactured by white blood cells to stimulate and activate the immune system. 

In an immune system disorder such as psoriasis, too much TNF is produced, causing the body to attack healthy tissues. In the case of psoriasis, this sequence of events affects healthy skin cells, causing them to turn over at a significantly faster rate than normal. Usually, it takes skin cells around 30 days to form, mature, and die off. With psoriasis, this cycle is shortened to as few as three to six days.

The result is an accumulation of cells on the surface of the skin: New cells are created more quickly than old ones can die and flake away. Most often the buildup of skin cells forms a rash made up of scales, or plaques, although there are some types of psoriasis in which skin changes are different. For example, in pustular psoriasis, fluid-filled lesions form on the skin. In guttate psoriasis, the rash is characterized by lesions shaped like teardrops.

Genetics

The immune system glitch that causes psoriasis is believed to be hereditary. Although the link between genetics and psoriasis isn't fully understood, according to the NPF, around 25 individual variations in genes that may increase a person's likelihood of having psoriasis have been identified.

Having one (or more) of the genes that create a predisposition to psoriasis isn't a guarantee that you will develop the condition, however; the National Institutes of Health reports that only about 3.2 percent of adults have psoriasis.

One thing scientists are working on is identifying specific genes that cause specific types of psoriasis. Research has found, for example, that when triggered by an environmental factor such as an infection, a mutation called CARD14 may be involved in plaque psoriasis and psoriatic arthritis. CARD14 might also be associated with pustular psoriasis.

Understanding the role that genes play in psoriasis is important. It can help scientists come up with treatments that may be more effective and targeted.

Risk Factors

While it may be true that your genetics have laid the groundwork for developing psoriasis, for some, the presence of another risk factor may be needed to make that possibility a reality. Some of the same risk factors that can "spark" the condition initially can also cause it to flare over time.

Infections

Any type of infection can cause psoriasis to appear or flare. This is especially important to note in the case of guttate psoriasis, which almost always follows an infection—in particular, a strep infection. Guttate psoriasis is the second most common type of psoriasis, according to the NPF, and mostly strikes children and young adults. The rash of guttate psoriasis is made up of small, teardrop-shaped lesions.

HIV is another infection that's often associated with psoriasis. People with HIV don't have psoriasis any more often than those who don't, but the severity of the condition is much worse for them. This isn't surprising, given that HIV suppresses the immune system, which is directly involved in psoriasis.

Skin Injury

Any sort of trauma to the skin—a cut or scrape, a surgical procedure, even a tattoo or a sunburn—can cause a flare of psoriasis known as the Koebner phenomenon. Scientists don't totally understand why a skin injury would have this effect in someone with psoriasis but suspect that a combination of cytokines, stress proteins, adhesion molecules, and autoantigens may converge to contribute to Koebner reactions.

It often doesn't take much to trigger Koebner lesions. Sometimes simply rubbing against the skin will do it, so if you have psoriasis it's important to protect your skin as much as possible. Wear long sleeves and pants when working in the yard, for example. And always treat minor skin injuries right away. Clean scrapes and cuts with soap and water, apply an antibiotic ointment, and cover with a bandage. See your dermatologist for wounds that are slow to heal or for signs of infection such as unusual pain, heat, or redness.

Obesity

Research suggests that obesity is a significant risk factor for psoriasis. It's hypothesized that this is because 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).

Obesity also can affect psoriasis treatment, increasing the risk of side effects from medications and lowering the effectiveness of certain treatments that have to be adjusted according to body weight. 

Medications

The following are just some of the drugs and classes of drugs shown to worsen some or all types of psoriasis:

  • High blood pressure medications including beta-blockers, such as Inderal (propranolol); and angiotensin-converting enzyme (ACE) inhibitors, such as Vasotec (enalapril) and Altace (ramipril)
  • Lithium, which is prescribed to treat bipolar disorders
  • Antimalarials, such as Plaquenil (hydroxychloroquine) and Aralen (chloroquine), have been found to cause psoriasis flares in around 30 percent of people who take them. Plaquenil sometimes is used to treat lupus and rheumatoid arthritis.
  • Interferons, prescribed mainly to treat hepatitis C 
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Terbinafine, an antifungal
  • The antibiotic tetracycline
  • Tumor necrosis factor-a inhibitors, including Remicade (infliximab), Humira (adalimumab), and Enbrel (etanercept). Ironically, these are often used to treat chronic psoriasis and psoriatic arthritis, but in rare cases have been found to exacerbate the condition instead.
  • Tar and anthralin (common topical treatments for plaque psoriasis)

While oral steroids may be prescribed to help clear psoriasis, they can also have a dangerous side effect: Stopping oral or topical steroids sometimes can cause psoriasis to come back with a vengeance. If you have psoriasis and are prescribed an oral corticosteroid to treat another condition, talk to your dermatologist or the doctor who's managing your psoriasis.

Lifestyle and Environment

In particular, how and where you live can play a role in the development of psoriasis and your ability to manage it effectively.

Smoking

Given how harmful cigarettes are to health in general, it's not surprising that there's research showing a strong association between smoking and psoriasis. Not only does smoking increase a person's risk of developing psoriasis, the amount a person smokes has an impact on how serious their psoriasis is and how well they respond to treatment. In other words, people with psoriasis who smoke may not get the full benefits of medications and other therapies.

Stress

Stress has an enormous impact on the immune system and, therefore, can play a significant role in psoriasis. To complicate matters, when psoriasis breakouts occur, they can cause stress and anxiety that can further exacerbate them.

Emotional stress can come in many forms. Though virtually unavoidable, there are ways to help control it that may, in turn, help keep psoriasis flares at bay, including regular exercise (even daily walks), yoga, meditation, and deep-breathing techniques. Physical stress—from surgery, say, or childbirth—is also a common trigger for psoriasis outbreaks.

Cold Weather

Low temperatures sap the air of moisture, which in turn leads skin to be dry. For this reason, people with psoriasis often have flare-ups in winter or when they visit a cold climate. Cold weather periods are also associated with less sunlight. Ultraviolet radiation (rays from the sun) is beneficial to psoriatic skin. Too much sun can be a problem as well, though. A sunburn can cause psoriasis to develop in the areas of skin that become burned.

Gluten

Some studies have found that certain people with psoriasis have high levels of gluten antibodies, an indication that they're reacting to gluten in their diet (even if they haven't been diagnosed with celiac disease or non-celiac gluten sensitivity). Much more research needs to be done to confirm that there's truly a link between gluten in the diet and psoriasis.

However, if you happen to have psoriasis and also have been diagnosed with celiac disease, you'll need to follow a gluten-free diet in order to treat your celiac disease. As a bonus, it might help your psoriasis. You may even see an improvement in your skin if you have psoriasis in addition to high levels of antibodies to gluten in your blood and decide to cut gluten from your diet, according to the NPF

View Article Sources