Psoriatic arthritis often occurs with psoriasis. The exact cause is unclear, but it may result from faulty immune activity. Some triggers and risk factors such as an infection, may increase the risk.

Statistics suggest that around 20% of people with psoriasis also develop psoriatic arthritis (PsA).

In this article, we will look at some possible causes, triggers, and risk factors for PsA.

PsA causesShare on Pinterest
Tridsanu Thophet/EyeEm/Getty Images

Experts do not yet know precisely why PsA occurs.

Link with psoriasis

Research suggests a link between psoriasis and PsA, although the exact link is not yet clear. PsA is far less common among people who never develop psoriasis.

Among those with PsA, 68% have skin symptoms before arthritis appears, while 15% develop arthritis and skin lesions at the same time. Another 17% of people with PsA go on to develop skin symptoms.

Both psoriasis and PSA seem to involve problems with the immune system. The immune cells attack healthy joint tissue, causing inflammation, swelling, and pain.

However, it is unclear why PsA affects some people with psoriasis and not others.

Genetic factors

Genetic factors appear to play a role.

Over 40% of people with PsA have a family member with the condition, and scientists have identified genetic features that appear to be linked to it.

Environmental factors

Some environmental factors may make some people more susceptible to PsA, such as a mechanical injury or an infection.

These appear to set off a chronic inflammatory process, mainly in the joints and skin, that involves the release of a substance known as IL-23. IL-23 is a substance known as a cytokine. It is part of the immune response and has pro-inflammatory properties.

As well as IL-23, the cytokine IL-17, tumor necrosis factor (TNF), and specific immune cells also contribute.

One treatment for PsA is a biologic drug known as an IL-23 inhibitor. This medication aims to reduce symptoms by blocking the action of IL-23.

Other factors

PsA can occur at any age, but it is more likely to appear between the ages of 30 and 50 years.

There is evidence that the following factors may play a role in both the onset of PsA and the occurrence of flares:

  • smoking
  • obesity
  • some gut issues, such as subclinical colitis and reduced diversity in the gut microbiome
  • having scalp psoriasis, severe skin psoriasis, and psoriatic nail changes

Experts note that the complexity of interacting factors may make it hard to pinpoint precise environmental causes.

A flare is a time when symptoms worsen. Between flares there may be times of remission, when there are few or no symptoms.

Possible triggers for a PsA flare include:

  • stopping PsA medications, such as steroids
  • infections or wounds
  • stress or depression, which can lead to inflammation

Understanding the potential triggers of PsA flares increases the chance of preventing them. Keeping a journal may help a person identify and avoid their triggers.

Sharing this information with a doctor can help a person identify effective treatments or simple lifestyle changes that could improve symptoms.

Learn more about the diagnosis and treatment of PsA here.

Here are some questions people often ask about the causes of PsA.

What are the main causes of psoriatic arthritis (PsA)?

PsA is an inflammatory disease that often affects people with psoriasis. Genetic features appear to play a role, and environmental factors — such as an injury or infection — may contribute.

Where does PsA usually start?

The early signs of PsA include tender or swollen joints, eye inflammation, and swelling in the fingers, known as dactylitis and sometimes called “sausage fingers.”

Is PsA serious?

Without treatment, PsA can lead to severe pain and permanent joint damage. It can also reduce mobility, affect quality of life, and it may increase the risk of conditions such as cardiovascular disease and other aspects of metabolic syndrome.

Not everyone will experience PsA in the same way, but it is essential to see a doctor early if a person may have PsA, as medication can help manage symptoms and slow its progress.

The exact causes of PsA are not yet clear. However, many scientists and medical professionals believe that it develops due to a faulty reaction in the immune system.

Genetic factors appear to play a role in the development of PsA, but environmental factors, such as an injury or infection, may increase the risk in those who are already susceptible. Risk factors for PsA include age and family history.

Early treatment can help manage PsA and slow its progression.