If you’re one of the 7.5 million Americans affected by psoriasis (PsO), you know the challenge of dealing with those red, scaly, itchy plaques that appear out of nowhere on places like your elbows, arms, and legs. Now imagine having to cope with a second disease on top of it—an equally painful condition that attacks, not your skin, but your joints.
That’s the reality for up to 30% of people with severe PsO who find themselves doing battle with psoriatic arthritis (PsA). As its name suggests, PsA can cause pain, stiffness, and swelling in your body, making everyday movement uncomfortable.
While one doesn’t guarantee the other, it’s a legit fear if you have psoriasis that it could turn into psoriatic arthritis in the future. Here’s what you need to know to stay one step ahead of the disease.
The PsO/PsA Link
You might wonder how a disorder that’s all about skin lesions could be connected to a condition focused on your joints. Wacky as it seems, though, they are intimately related. “Some people think of psoriasis and psoriatic arthritis as two diseases, and others think of them as a single entity, psoriatic disease,” says Ana-Maria Orbai, M.D., assistant professor of medicine and director of the Psoriatic Arthritis Program in the division of rheumatology at Johns Hopkins University in Baltimore. “Psoriatic disease can affect different parts of the body—like the skin and the musculoskeletal system, including the spine—and people’s symptoms can be different depending on the body part.”
The shared roots of PsO and PsA stem from an out-of-control inflammatory response in your body that sends your immune system into overdrive. In the case of psoriasis, the immune system attacks healthy skin cells, leading to red patches of skin covered with silver scales. In psoriatic arthritis, your immune systems zeroes in on joints, ligaments, and tendons instead.
What Are the Odds?
Despite the connection between conditions, most people with PsO won’t develop PsA. “The risk of psoriatic arthritis among patients with psoriasis is 10% overall, and up to 30% among patients with more severe psoriasis,” says John Davis III, M.D., a rheumatologist at the Mayo Clinic in Rochester, MN. “The longer someone has had skin psoriasis, the higher the risk of psoriatic arthritis.” There often is a gap of 10 to 20 years between being diagnosed with PsO and seeing symptoms of arthritis. Also, though less common, you might develop symptoms of PsA first, followed by skin symptoms of PsO later.
When symptoms of PsA do appear, it’s easy to overlook them at first. But bouts of persistent aches and soreness brought on by nothing in particular (no overly ambitious pickup game of basketball with your kids or dramatic falls on the black diamond trail), is a potential clue something’s up.
Couple that with swelling in your finger joints or ankles, or lower back pain that worsens with rest and improves with activity, and you’ve got the makings of a case for psoriatic arthritis. “Psoriatic arthritis is a musculoskeletal disease—it can affect everything from the small joints of your fingers to the larger joints in your knees,” says Dr. Orbai.
It’s more than joint pain, though: PsA also affects the spots where tendons and ligaments connect with bone or support the bone. A specific type of PsA-related inflammation called enthesitis can develop where tendons attach to your heelbone, leading to additional pain when you walk.
Know Your Risk Factors
Despite extensive research, scientists have yet to fully understand who will get PsA and who won’t. There is a genetic component to the disease: About 40% of people with PsA have at least one relative with either PsO or PsA.
In addition, certain factors make the progression of PsO to PsA more likely. “We know that people with scalp, intergluteal, and nail psoriasis have a higher chance of developing psoriatic arthritis,” says Dr. Orbai. “For example, people with scalp psoriasis—which commonly affects the back of the head, the front of the hairline, and behind the ears—have up to four times higher risk of psoriatic arthritis than people with other forms of the disease.”
And while only 40% of people with psoriasis have the nail form of the disease (pitted, deformed nails), the condition appears in 80% of people with the PsA, making nail psoriasis one of the leading risk factors for psoriatic arthritis.
Lifestyle Changes Can Help
If you have PsO, there are things you can do to try to lower your chances of developing PsA, too. “One modifiable risk factor is being overweight or obese,” says Dr. Orbai. “A possible explanation is that there might be more wear and tear on joints when someone is carrying more weight, which leads to inflammation. It could also be because inflammation is amplified by the fatty cells in the tissue.”
Regular exercise and smart food choices based on the Mediterranean diet (including leafy greens, fresh fruit, fish, and olive oil) can help you reach a healthy weight and lower inflammation in your body.
Other ways to reduce your chances of developing PsA? If you smoke, quit. Moderate your alcohol intake, avoid cold weather (well, as much as you can), and find ways to boost your mood: A 2017 Canadian study found that psoriasis patients who reported depression were at a 37% greater risk of developing psoriatic arthritis.
Dealing with Dual Diseases
There are no cures for either psoriasis or psoriatic arthritis, but the conditions are treatable, says Dr. Davis. Typically, you’ll start with drugs that target the inflammatory process affecting your skin and joints. “Once psoriasis and psoriatic arthritis are considered moderate to severe, a patient can try medications like injectable biologicals or infusible biologicals,” says Dr. Orbai. “There are psoriatic disease-specific biologicals like the interleukin-17 inhibitors and interleukin-23 inhibitors, and also biologicals known as TNF inhibitors approved by the FDA for both psoriasis and psoriatic arthritis.” Because the Interleukin-17 and Interleukin-23 inhibitors are specific to PsA, they probably won’t work if you have another form of arthritis, like rheumatoid, so proper diagnosis is key.
The good news: Drugs for these conditions keep getting better and better. “These diseases have a wide spectrum,” Dr. Davis says. “However, with today’s treatments and medications, there is increasing hope that we will be able to prevent permanent complications or joint damage if you are vigilant about taking medications and making lifestyle modifications.”
The most important thing to know is that PsA is chronic and progressive, so if you wait and do nothing, it will only get worse. Left untreated, PsA can cause permanent damage to your joints and ligaments. If you have psoriasis and think you might have symptoms of psoriatic arthritis—even if you’re not sure—it’s smart to talk with your doctor right away.