From the Journals

Rheumatoid arthritis linked to increased Parkinson’s risk


 

FROM JAMA NEUROLOGY

Rheumatoid arthritis (RA) is linked to almost a twofold increased risk for Parkinson’s disease (PD), new research shows.

Claims data in 55,000 patients with RA and 273,000 age- and sex-matched controls show that those with RA were 1.74 times more likely than controls to be diagnosed with PD.

“If patients with rheumatoid arthritis begin exhibiting motor symptoms such as muscle rigidity, tremors, or slowed movement, it is imperative that they be evaluated by a qualified neurologist to rule out the possibility of developing Parkinson’s disease,” study investigator Hyungjin Kim, MD, PhD, told this news organization.

Dr. Kim is an associate professor in the department of medical humanities at Sungkyunkwan University School of Medicine in Seoul, South Korea.

The findings were published online in JAMA Neurology.

Conflicting findings

The investigators note that a number of studies have examined the link between RA and PD, with conflicting results – one even showing a 35% reduced risk for PD for individuals with RA. A more recent population-based study in Taiwan showed a 37% higher rate of PD in patients with rheumatic disease.

However, previous studies did not control for important variables such as body mass index or diabetes.

For the current study, the investigators analyzed claims on about 55,000 patients diagnosed with RA between 2010 and 2017, with follow-up until 2019, and compared the outcomes of this group vs. those of 273,000 controls.

The mean age of claimants was 58 years, and 75% were female.

Results showed that those diagnosed with seropositive RA were about twice as likely as controls to be diagnosed with PD. Those with seronegative RA were 1.2 times as likely as controls to be diagnosed with PD.

Dr. Kim noted that although the pathogenic link between RA and PD remains elusive, inflammation probably plays an important role. “Inflammatory cytokines such as tumor necrosis factor alpha and interleukin-6, which are increased in RA patients, can induce microglial activation, leading to neuroinflammation,” he stated.

“These inflammatory cytokines are known to be associated with the dysfunction and degeneration of nigral dopaminergic neurons, which are important in the pathogenesis of PD,” he added.

The investigators noted that patients with RA may have been subject to more frequent health care services than controls and so were more likely to obtain a PD diagnosis.

Another possibility was that because patients with health check-ups were included in the analysis, the findings may have been biased toward those who were older and who had a higher income.

Dr. Kim noted that additional research is required to clarify the pathogenic connection between RA and PD.

“Moreover, additional studies are necessary to explore the potential influence of novel therapeutic treatments for RA on Parkinson’s disease susceptibility in patients with RA,” he said.

Commenting on the findings for this news organization, David Sulzer, PhD, professor of psychiatry, neurology, and pharmacology at Columbia University in New York, said that the study adds to the growing body of evidence showing there is an autoimmune component to PD.

Dr. Sulzer pointed to data in several papers he published with others to this effect, including one showing higher rates of PD in people with inflammatory bowel disease.

The study had no specific funding. The study investigators and Dr. Sulzer report no relevant disclosures.

A version of this article first appeared on Medscape.com.

Recommended Reading

New JAK inhibitor study data confirm benefit in alopecia areata
MDedge Internal Medicine
Tofacitinib may have possible protective effect against ILD in RA
MDedge Internal Medicine
FDA approves new formulation of Hyrimoz adalimumab biosimilar
MDedge Internal Medicine
DMARDs taper-to-discontinuation trial deemed inconclusive
MDedge Internal Medicine
Biosimilars and patients: Discussions should address safety, cost, and anxiety about change
MDedge Internal Medicine
Registry data ‘reassure’ on biologics’ heart attack risk in rheumatoid arthritis
MDedge Internal Medicine
Meta-analysis examines cancer risk concern for JAK inhibitors
MDedge Internal Medicine
Researchers seek to understand post-COVID autoimmune disease risk
MDedge Internal Medicine
FDA puts partial hold on investigational alopecia areata drug deuruxolitinib
MDedge Internal Medicine
Normal CRP during RA flares: An ‘underappreciated, persistent phenotype’
MDedge Internal Medicine