How Psoriasis and Psoriatic Arthritis Are Related
Psoriasis is a skin condition affecting about 2% of Americans. Psoriasis causes excess buildup of skin cells, triggering red, scaly patches (called plaques) to form in various areas on your body. If you have psoriasis, your immune system goes into overdrive, over-healing cuts and scrapes by producing too much inflammation—and sometimes, this will happen even without injury to your skin. This reaction causes red, scaly patches to form on the surface of your skin, which can be painful, uncomfortable, and irritatingly itchy.
As if dealing with psoriasis isn’t enough, up to 30% of psoriasis patients also develop psoriatic arthritis, a condition that causes joint pain, stiffness and swelling. Although psoriasis is visible on the skin and psoriatic arthritis is internal, the two conditions are closely linked.
Both conditions have to do with an abnormally functioning immune system, one that causes your body to attack itself from the inside. The result of this attack manifests itself in chronic inflammation—in psoriasis, this inflammation affects your skin, and in the case of psoriatic arthritis, inflammation affects your joints.
The typical symptoms of psoriatic arthritis are swelling of your knee and ankle joints, reduced mobility, and pain or tenderness. Inflammation can affect your fingers and toes, resulting in dactylitis, a particular type of swelling that causes digits to look like sausages. Also, psoriatic arthritis can cause enthesitis: inflammation in areas where your tendons and ligaments hook into bone.
Pain varies greatly from patient to patient. Some people experience no pain at all, while some are not able to carry out daily functions. Often, patients describe the feeling of psoriatic arthritis as having a bruise or injury that keeps throbbing and does not subside. Many patients with severe psoriatic arthritis are disabled to the point that they cannot even wash or dress themselves. The number of joints involved and to what degree they are affected determines a patient’s pain level.
How Psoriatic Arthritis Differs From Other Types of Arthritis
While different types of arthritis, such as rheumatoid arthritis (RA), can also co-occur with psoriasis, there are some key differentiators we look for when diagnosing psoriatic arthritis. The diagnosis of psoriatic arthritis involves an assessment of the clinical appearance of the arthritis, the presence of enteritis (inflammation of the intestines), and back pain. The back pain is often lower back pain, which is associated with an unusual amount of stiffness lasting for more than 45 minutes in the morning when getting up—but it gets better with activity and exercise, unlike back pain from wear and tear. Also, a magnetic resonance imaging (MRI) scan may be used to examine specific areas of inflammation. Mainly, the appearance and symptoms of the patient are the most important indicators of whether a person has psoriatic arthritis.
RA is not directly linked to psoriasis, although it often coincides with the skin condition, because both are fairly common in the population. Rheumatoid arthritis affects 3% of Americans, and focuses mainly on small joints in your hands and feet. It is important to note that RA generally does not cause inflammation in tendons or ligaments, and it doesn’t create sausage-like digits or affect larger joints in your body like psoriatic arthritis does. Seeing your rheumatologist is necessary to differentiate between psoriatic arthritis and rheumatoid arthritis, since there are separate treatments for each.
Treating Psoriatic Arthritis
As far as treatments go, select psoriasis treatments such as methotrexate and several biologics like etanercept (Enbrel), adalimumab (Humira), ustekinumab (Stelara) and a number of others including apremilast (Otezla), certolizumab (Cimzia), golimumab (Simponi), and inflizimab (Remicade) can be used for both psoriasis and psoriatic arthritis.
The overlap between some treatments is in part due to their effect on inflammatory proteins called cytokines—reducing the levels of these proteins can cause relief in both skin and joints. Basically, some of the inflammation pathways that cause plaques in your skin also affect your joints. It is important to understand that not all cytokines affect both your skin and your joints; thus, while some treatments can be used for both psoriasis and psoriatic arthritis, this cannot be said for all.
In addition to medication, you may be referred to physical or occupational therapy, based on your level of mobility, to help you with everyday tasks like washing, dressing and even cooking meals. We also may give you pain relievers such as ibuprofen (Advil) and naproxen (Aleve).
Beyond therapy, there are low-impact exercises like yoga, Tai Chi and water exercises you can do on your own to help relax stiff muscles, reduce soreness in joints and promote circulation to improve your range of motion and mobility.
If there is any concern about arthritis or inflammation in general, the best thing you can do for yourself is to get a proper and early diagnosis. Genetics is the main reason for the co-occurrence of psoriasis and psoriatic arthritis; however, psoriatic arthritis can also occur in patients without a family history of the condition. Getting an early evaluation and effective treatment can greatly improve your quality of life and preserve your joints.