A photo of a person's hand suffering from joint pain, as evident by red pain spots on the finger.

Key Takeaways 

  • The chronic inflammation caused by rheumatoid arthritis (RA) has been shown to increase the risk of developing Parkinson disease (PD). 
  • Patients with rheumatoid arthritis (RA) should be aware of their elevated risk of Parkinson disease (PD) and work closely with their care provider to monitor inflammation.  
  • Physicians should be aware of the increased risk of Parkinson disease (PD) among their patients with rheumatoid arthritis (RA) and refer them promptly to a neurologist at the first sign of motor symptoms. 

It turns out that there is a potential link between rheumatoid arthritis (RA) and an increased risk of developing the neurological disorder Parkinson’s disease (PD).  

New research, which examined data from nearly 55,000 patients with RA, revealed that they were nearly twice as likely to receive a PD diagnosis compared to those without the autoimmune disease. 

Previous studies have explored the potential connection between RA and PD, but the results have been inconsistent. In fact, one study suggested a lower risk of PD (35 percent reduced risk) for individuals with RA while a more recent study, conducted in Taiwan, revealed that patients with rheumatic disease, including RA, had a higher rate of PD (37 percent higher rate) compared to the general population. 

It’s important to note that previous studies did not account for such factors as body mass index or diabetes, which could influence the results.  

About the Study

To address this gap, the researchers conducted a new study. They analyzed data from 54,680 patients diagnosed with RA between 2010 and 2017, including 39,010 with seropositive RA and 15,670 with seronegative RA. Seropositive refers to the presence of RA autoantibodies in the blood and means a high level of rheumatoid factor is present. Seronegative means these autoantibodies are not in the blood. 

The study followed these patients until 2019 and compared their outcomes to a control group of 273,000 individuals. The average age of the participants in the study was 58 years, and about 75 percent of them were female.  

Individuals eligible for the study needed: 

  • A registered diagnostic code for RA to show they were diagnosed between 2017 and 2020 
  • A 180-day or more prescription for any arthritis inflammation medication, including DMARDs, bDMARDs, or tsDMARDs 
  • Proof of enrollment by a physician in the Rare and Intractable Disease (RID) program for seropositive RA (SPRA) 
  • A national health checkup within two years before the RA diagnosis date, which provided medical and health behavior information from the health screening 

The Study Findings

Researchers found that people with RA had a 1.74-fold higher risk of developing PD compared to those without RA. This means that RA could be linked to an increased chance of getting PD. They also discovered that the occurrence of PD was significantly higher in those with SPRA, a more severe form of RA.  

To make sure the results were reliable, the researchers compared the characteristics of the participants and adjusted for different factors such as age, gender, smoking, alcohol drinking, physical activity, low income, body mass index (BMI), and other medical conditions like diabetes, hypertension, hyperlipidemia, chronic kidney disease, myocardial infarction, stroke, and depression. 

They looked at the influence of factors like menopause, age at menopause, and hormone replacement therapy (HRT). While more research is needed to fully understand these factors, researchers found that the association between RA and PD was stronger in women who hadn’t reached menopause yet compared to women who had. This suggests that RA could have a bigger impact on PD risk in younger women who don’t have other PD risk factors like age and estrogen deficiency.  

Researcher also examined the relationship between the type of medication used to treat RA and the risk of developing PD. They found that people who used certain types of DMARDs, called bDMARDs, didn’t have an increased risk of PD, while those who didn’t use these medications had a higher risk.  

This suggests that bDMARDs might help lower the risk of PD in people with RA. Another study found a similar result in patients with inflammatory bowel disease. However, the number of participants using these medications was small, so more studies are necessary to fully explore the benefits of DMARDs in relation to PD risk. 

What This Means for You

While more research is needed to understand how RA and PD are connected, this study indicates that doctors who treat patients with RA should be aware of the higher chance of developing PD. If you have RA and start experiencing early motor problems that are not related to inflammation, it is a good idea to talk to your doctor about seeing a neurologist. 

If you or someone you know has RA and is experiencing a decline in motor skills, it is important to contact your health care provider right away to discuss the possibility of seeing a neurologist. 

Be a More Proactive Patient with ArthritisPower

ArthritisPower is a patient-led, patient-centered research registry for joint, bone, and inflammatory skin conditions. You can participate in voluntary research studies about your health conditions and use the app to track your symptoms, disease activity, and medications — and share with your doctor. Learn more and sign up here.

Bacelis  J, et al. Decreased risk of Parkinson’s disease after rheumatoid arthritis diagnosis: a nested case-control study with matched cases and controls.  J Parkinsons Dis. 2021;11(2):821-832. doi: https://doi.org/10.3233/JPD-202418.

Chang  CC, et al. Autoimmune rheumatic diseases and the risk of Parkinson disease: a nationwide population-based cohort study in Taiwan. Ann Med. 2018;50(1):83-90. doi: https://doi.org/10.1080/07853890.2017.1412088

Kang J, et al. Rheumatoid Arthritis and Risk of Parkinson Disease in Korea. JAMA Neurology. 2023. doi: https://doi.org/10.1001/jamaneurol.2023.0932.

Li  X, et al. Subsequent risks of Parkinson disease in patients with autoimmune and related disorders: a nationwide epidemiological study from Sweden. Neurodegener Dis. 2012;10(1-4):277-284. doi: https://doi.org/10.1159/000333222

Rugbjerg  K, et al.  Autoimmune disease and risk for Parkinson disease: a population-based case-control study. Neurology. 2009;73(18):1462-1468. doi: https://doi.org/10.1212/WNL.0b013e3181c06635.

Sung  YF, et al. Reduced risk of Parkinson disease in patients with rheumatoid arthritis: a nationwide population-based study. Mayo Clin Proc. 2016;91(10):1346-1353. doi:https://doi.org/10.1016/j.mayocp.2016.06.023

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