Psoriatic Arthritis vs. Multiple Sclerosis: What Are the Differences?

Psoriatic arthritis (PsA) and multiple sclerosis (MS) are both autoimmune diseases. They occur when the immune system malfunctions and attacks healthy cells and tissue. With PsA, the immune system attacks the skin and joints. With MS, attacks focus on the protective coverings of nerve cells of the brain, spinal cord, and eyes.

Both PsA and MS are progressive diseases, which means they will get worse with time. It is, therefore, important to get an early diagnosis and treatment to reduce the complications and damage these conditions can cause.  

This article will discuss PsA vs. MS, including symptoms, causes, and treatment. 

Symptoms

Some symptoms of PsA and MS are similar because the underlying processes of these two conditions are alike. These conditions also have many differences. Both have symptoms that come and go in the form of flare-ups (times of higher disease activity and more symptoms) and remission (times of fewer symptoms and reduced disease activity).

Psoriatic Arthritis

PsA affects less than 1% of the American population. But PsA affects about 30% of people with psoriasis, an inflammatory skin condition that causes red patches of skin with silvery scales to pile up.

Joint pain, stiffness, and swelling are the main symptoms of PsA. They can affect any part of the body, including the fingers and toes, hands and feet, and the spine.

PsA affects joints on one or both sides of the body and can sometimes resemble another type of inflammatory arthritis called rheumatoid arthritis, which causes inflammation in the lining of joints.

Additional symptoms of PsA are:

• Joint warmth and redness may occur.
• Dactylitis: Swollen fingers and toes result, with the digits becoming so swollen they resemble small sausages.
• Enthesitis: This is inflammation of the entheses, the places where tendons and ligaments attach to bone. The feet are frequently affected, especially the backs of the heels and the soles of the feet.
• Low back pain: Some people with PsA develop a condition called spondylitis, inflammation of the joints of the vertebrae of the spine. Pain can include sacroiliitis, inflammation of the joints where the spine and pelvis meet.
• Skin symptoms: Symptoms include thick, red patches of skin covered by silver scales. These patches are itchy and sore and can appear anywhere on the body but are frequently seen on the elbows, knees, scalp, hands, and soles of the feet.
• Nail changes: Changes include pitting, crumbling, and nail bed separation.
• Eye inflammation: A condition called uveitis may occur, which can cause eye pain, redness, and blurry vision. Uveitis can lead to vision loss if left untreated.

PsA is sometimes confused with MS. This is because it is a type of spondyloarthritis, an umbrella term for conditions that cause inflammation of the spine. Symptoms of spondyloarthritis can overlap with MS.

According to a study reported in 2019 in the journal Multiple Sclerosis and Related Disorders, as many as 7% of MS diagnoses were actually spondyloarthritis conditions.

Multiple Sclerosis

Symptoms of MS can vary from person to person and depend on the amount of nerve damage and what nerves might be affected. Some people with MS may have long periods of remission, whereas others may lose their ability to walk or care for themselves.

Symptoms of MS can affect movement, vision, and function. Common symptoms include:

• Numbness or weakness of the limbs, frequently affecting one side of the body at a time
• Electric shock sensations that are felt with certain movements, especially when bending the neck
• Muscle stiffness and spasms
• Tremors
• Lack of coordination or an unsteady gait
• Eye problems (which usually affect one eye at a time) such as partial or complete vision loss, pain with eye movement, double vision, and/or blurred vision
• Slurred speech
• Dizziness
• Fatigue
• Tingling or pain in different body areas
• Problems with sexual, bowel, or bladder function

Causes

As with all autoimmune diseases, the causes of PsA and MS are unknown. One theory as to what might cause an autoimmune disease is that some types of microorganisms (such as bacteria or viruses) or drugs can trigger changes that confuse the immune system and lead it to malfunction. This might happen to people who already have genes that make them susceptible to autoimmune diseases.

Psoriatic Arthritis

Incorrect immune system responses in PsA cause the immune system to attack the joints and promote the overproduction of skin cells. Researchers believe PsA can develop from both genetic and environmental risk factors.

Many people with PsA have a family member with PsA or with psoriasis, or they may have psoriasis themselves. Researchers have discovered certain genetic markers that are linked to the development of PsA.

Researchers also know that certain triggers—such as physical trauma, chronic stress, infections, or environmental factors (like toxins)—might trigger PsA in people who have genes linked to PsA.

Risk factors for PsA are:

• Psoriasis: Having psoriasis is the single greatest risk factor for PsA.
• Family history: A family history of psoriatic disease (PsA and/or psoriasis) can raise your risk.
• Age: Anyone can develop PsA, but it seems to occur most frequently in adults between the ages of 35 and 55.
• Smoking: Smoking is associated with oxidative stress, which can promote chronic inflammation.

Multiple Sclerosis

The specific cause of MS is unknown. With MS, a malfunctioning immune system destroys the myelin sheath—the fatty substance coating and protecting the fibers of the brain and spinal cord. When myelin is damaged and nerve fibers are exposed, the messages that travel along those nerve fibers are blocked or slowed down.

Researchers don’t know why MS develops in some people and not in others. What they do know is that a combination of genetics and environmental factors is to blame.

Risk factors linked to MS are:

• Age: MS can affect anyone regardless of age, but onset is usually around 20–40 years of age.
• Sex: Females are 3 times more likely to have MS than males.
• Certain infections, including Epstein-Barr, the virus responsible for infectious mononucleosis may trigger MS.
• Race: White people seem to have the highest risk for MS.
• Vitamin D: Having low vitamin D and low exposure to sunlight increase MS risk. MS is more common in areas farther from the equator.
• Having other autoimmune diseases increases risk.
• Being a smoker: Smokers are more likely than nonsmokers to have MS.

Diagnosis

There is no single test that can confirm a person has PsA or MS so, doctors will employ a variety of different methods to figure out what is causing your symptoms.

Psoriatic Arthritis

Diagnosing PsA starts with looking for telltale signs of the condition. This includes inflammation of one or more joints, tendon inflammation, swollen fingers and toes, spinal inflammation, and nail and skin symptoms. In addition, your doctor will ask about any family history of PsA or psoriasis or personal history of psoriasis.

Blood work that can help diagnose PsA include rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody testing. RF is a protein found in the blood of people with rheumatoid arthritis. RF and anti-CCP testing in people with PsA will be negative.

X-rays of the hands and feet might also be done to look for any bone or joint damage that may have occurred early on with PsA. PsA often causes bone erosion and joint damage that is not seen with other rheumatic conditions.

Your doctor might request additional tests and blood work to rule out other conditions with similar symptoms, especially if they are still unsure of your diagnosis.

Multiple Sclerosis

A diagnosis of MS relies on ruling out other conditions that might cause similar signs and symptoms. Your doctor will likely start with getting a detailed medical history and physical examination that includes:

• Medical history: Your doctor will ask you about past and present symptoms that you are experiencing. They will also ask about your family history of MS or other autoimmune diseases and your environmental exposures and other illnesses.
• Neurological exam: A neurological examination looks at vision, hearing, strength, swallowing, facial sensations, reflex, coordination, gait, and balance examination.

Your doctor will also request additional testing, including:

• Blood work: Blood tests help rule out other conditions that cause similar symptoms. Bloodwork also looks for specific molecular biomarkers linked to MS, which can help in diagnosis.
• Spinal tap (lumbar puncture): A small sample of cerebrospinal fluid is taken from the spinal canal. Spinal fluid can contain abnormalities in antibodies linked to MS. This test can also rule out infections and other conditions with similar symptoms as MS.
• Magnetic resonance imaging (MRI) scans: These can reveal MS lesions on the brain and spinal cord. Sometimes contrast is used to highlight lesions to figure out if the disease is active.
• Evoked potential tests: These tests record electrical signals produced by the nervous system in response to stimulation.

Treatment  

Both PsA and MS are lifelong conditions without a cure. Treatment for both conditions can help manage symptoms, slow down disease progression, prevent complications, and improve your quality of life.

Psoriatic Arthritis

Treatment for PsA focuses on controlling inflammation to prevent joint damage and control skin symptoms. A treatment plan will depend on how severe your disease is and what joints are affected. You may need to try different treatments before you find one that manages your symptoms of PsA.

Medications your doctor might prescribe for PsA include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) relieve pain and inflammation in mild PsA.
• Conventional disease-modifying antirheumatic drugs (DMARDs) slow down disease progression and reduce inflammation that could lead to permanent damage. The most-prescribed DMARD is Otrexup (methotrexate).
• Biologic DMARDs target different pathways in the immune system and reduce the effects of the immune system. Common biologics for treating PsA are Humira (adalimumab), Remicade (infliximab), Orencia (abatacept), and Cosentyx (secukinumab).
• Janus kinase (JAK) inhibitors work to taper down the immune system and prevent inflammation.
• Otzela (apremilast) blocks an enzyme called phosphodiesterase type 4 (PDE4) to control inflammation.

If PsA causes skin symptoms, your doctor might prescribe topical treatments, including corticosteroid creams, anti-inflammatory medications, and phototherapy to help reduce skin patches, itching, and skin pain.

Most people with PsA will never need surgery, but surgery is recommended if your joints have been severely damaged by PsA. Surgery can help to relieve pain and improve mobility.

Multiple Sclerosis

Many medicines can help people with MS to manage the effects of their disease. It is important to work closely with your doctor to find the best treatment plan that works for you and causes the least side effects.

Medicines used to treat MS include:

• DMARDs slow down the progression of the disease and prevent flare-ups. They also work to calm down the immune system so that it does not attack myelin.
• Beta interferons ease symptoms and reduce flare-ups.
• Copaxone (glatiramer acetate) stops the immune system from attacking myelin.
• Mavenclad (cladribine) or Tecfidera (dimethyl fumarate), among others, affect the immune system and reduce MS symptoms.
• Chemotherapy drugs, including Lemtrada (alemtuzumab) and Novantrone (mitoxantrone), are used to curb the immune system and keep it from attacking myelin.
• Corticosteroids are used for treating flare-ups of MS.
• Plasma exchange may be done when MS flare-ups don’t respond to steroids. This involves the removal of some of your blood. The plasma (liquid part) is then separated and discarded. The blood cells are mixed with a protein solution or donor plasma and put back into the body.

Your doctor may also recommend treatments to manage specific symptoms, including:

• Muscle relaxants for muscle stiffness and spasms
  
• Medicines to manage fatigue
• Antidepressants to manage mood symptoms
• Medicines like Ditropan (oxybutynin) and Detrol (tolterodine) to manage bladder symptoms

Physical therapy and occupational therapy can also help manage symptoms of MS. A trained healthcare professional can show you how to exercise to stay active. They can also teach you how to use assistive devices, such as a cane or walker, so you can get around more easily.

Lifestyle Disease Management

People with PsA and MS can benefit from making healthy lifestyle choices. These might include:

• Getting plenty of rest: Make sure you are getting the best sleep you can to keep you alert, active, and keep your pain levels down.
• Stay active: If you have mild to moderate symptoms of PsA or MS, regular, light exercise can improve your strength, balance, and coordination. This can include activities like swimming, walking, stationary bicycling, and yoga.
• Eat a balanced diet: While there isn’t any specific evidence that diet can reduce symptoms of PsA or MS, a healthy diet might help to keep inflammation down, relieve symptoms, keep your medicines working well, and reduce your risk for disease complications or other serious health conditions.
• Manage stress: Stress can trigger or worsen symptoms of PsA and many people with MS think it affects their condition also. Some stress relief activities to help you manage stress are yoga, tai chi, massage, or deep breathing.

Prevention

PsA and MS are not preventable diseases. If you have a family history of PsA, MS, or another autoimmune disease, ask your doctor to help you identify risk factors for these conditions.

With PsA, researchers know that some people have a higher risk for the condition, but there is no treatment or tool to prevent a person from getting PsA. Much like PsA, the development of MS cannot be predicted or stopped. However, it is possible to slow down disease progression in both conditions and prevent flare-ups.

Summary

Psoriatic arthritis and multiple sclerosis are both autoimmune diseases that result when the immune system malfunctions and attacks healthy tissues. In PsA, the immune system attacks skin and joints, and with MS, those attacks are directed toward the myelin sheath, the protective covering on nerve fibers of the brain, spinal cord, and eyes.

There is no cure for PsA or MS, and both conditions will get worse with time.  Early diagnosis and aggressive treatment are vital to slowing down disease progression and reducing the potential for complications of these conditions.

A Word From Verywell  

If you are diagnosed with psoriatic arthritis or multiple sclerosis, make sure you check in with your treating doctor regularly. PsA and MS are aggressive conditions and need strong medicines to reduce the potential for serious complications.

These conditions can also affect the organs, especially the eyes, so be sure to discuss your risk for other conditions, their symptoms, and preventive measures. It is important to work with a rheumatologist (a specialist in conditions affecting the joints and the musculoskeletal system) and other specialists to manage PsA or MS. This is the best way to improve your prognosis and maintain quality of life.