Causes and Risk Factors of Psoriatic Arthritis

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Psoriatic arthritis is a chronic inflammatory type of arthritis associated with the skin condition psoriasis. If not properly treated and managed, it can be progressive and lead to permanent joint damage and disability. 

It is an autoimmune disease the affects both the joints and skin and typically runs in families. The exact cause of psoriatic arthritis is unknown but the disease has a genetic component, along with immunologic and environmental risk factors.

Common Causes

There are three main aspects researchers have identified that contribute to the development of psoriatic arthritis: autoimmune changes, environmental exposures, and genetic risk factors. 

An autoimmune disease is a condition where the immune system mistakenly attacks the body. Psoriatic arthritis may result from an infection that activates the immune system. Streptococcal infections, such as strep throat, are a suspected trigger for the autoimmune response that leads to psoriatic arthritis.

Various immune system abnormalities also contribute to an increased risk of psoriatic arthritis. Activated T cells are present in the tissue of both the skin and the joints. It is also thought that cytokines, such as TNF-alpha, play a role in the inflammatory process which leads to cartilage destruction and skin inflammation associated with psoriatic arthritis.

Genetics

Approximately 40 percent of patients with psoriasis or psoriatic arthritis have family members who also have the condition. Studies show patients with a family history of psoriatic arthritis are up to 48 times more likely to develop the disease than those without a family history. Psoriatic arthritis is considered "more highly heritable" than other autoimmune diseases.

Children of parents with psoriasis are three times more likely to develop psoriasis and have a greater risk of developing psoriatic arthritis compared to children of parents without psoriasis. Similarly, if an identical twin has psoriatic arthritis, the other identical twin is highly likely to also have the disease or to develop it eventually.

Many genes associated with increased susceptibility of psoriatic arthritis are also linked to psoriasis. But not all genes are associated with both diseases.  

Lifestyle Risk Factors

There are environmental factors that appear to be related to the risk of developing psoriatic arthritis. Exposure to certain infections is considered a possible risk factor. Psoriatic arthritis is also more common in people who have been infected with the human immunodeficiency virus (HIV) compared to the general population.  

Other lifestyle factors that may influence the development of psoriatic arthritis include heavy lifting, injuries, infections that require antibiotics, and smoking. 

A 2011 study of 159 patients with psoriasis who went on to develop psoriatic arthritis found lifting cumulative loads of more than 100 pounds per hour was associated with a 2.8-times greater risk of developing the disease, and prior injuries corresponded with a 2.1-times greater risk.

One aspect that can affect the development of rashes in people with psoriatic arthritis is known as the Koebner phenomenon. This is when psoriatic lesions form in new places following skin trauma, such as a cut, bruise, or burn, or simply from the skin getting irritated from rubbing against a waistband, belt buckle, shoe, or bra strap. The cause of the Koebner phenomenon is unclear but cytokines, stress proteins, adhesion molecules, and autoantigens may be involved.

A Word From Verywell

While many of the risk factors for psoriatic arthritis are not modifiable, there are things you can do to manage the condition. Talk to your rheumatologist about medications and lifestyle changes that can help maintain your quality of life.

Reducing stress, following a healthy diet, keeping skin hydrated, maintaining a healthy weight, engaging in moderate, low-impact exercises, and avoiding smoking and drinking alcohol are things you can do to help reduce inflammation and prevent flare-ups of joints and skin.

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