Rheumatoid Arthritis May Raise Parkinson’s Risk

A retrospective cohort study called Rheumatoid arthritis and risk of Parkinson disease in Korea, published in JAMA Neurology, investigated the association between rheumatoid arthritis (RA) and Parkinson’s disease (PD) in over 328,000 participants in Korea. While on the surface, RA, an autoimmune disease, and PD, a neurodegenerative disorder, do not seem to have much in common, chronic inflammation may lie at the root of both of these conditions. A few studies have in fact noted that the incidence of RA and PD may be related, but these results have been conflicting and not entirely conclusive.

Researchers utilized data from the National Health Insurance Service (NHIS), a universal social insurance program that covers nearly the entire Korean population, to explore the link between RA and PD incidence. Within this cohort, 39,010 had seropositive RA (SPRA) and 15,670 had seronegative RA (SNRA); 273,400 matched controls did not have RA. The majority of participants were female with a mean age of 58.6 years.

After a mean follow up of 4.52 years, 290 participants diagnosed with RA had developed PD, while 803 of the matched controls developed PD, corresponding to a 1.74-fold higher risk for PD in the RA group. Furthermore, participants who had SPRA had a higher risk of PD than participants who had SNRA. Premenopausal women and those who did not use biological disease-modifying antirheumatic drugs also had an increased risk of developing PD. Researchers recommend that clinicians should be aware of the association between RA and PD and should refer patients with RA presenting with early signs of PD without synovitis to a neurologist.

It’s important to note that, in this study, disease activity was not taken into account and therefore it is unknown whether the risk of PD is affected by RA disease severity. Additional variables such as genetic contributors and environmental exposure were also not taken into account. As disease prevalence differs across various geographic regions, additional studies should be conducted in other populations to confirm these results.

Citation:

Kang, J., et al. (2023). Rheumatoid Arthritis and Risk of Parkinson Disease in Korea. JAMA neurology, 80(6), 634–641. https://doi.org/10.1001/jamaneurol.2023.0932