A recent study demonstrates how the chronic inflammation that characterizes rheumatoid arthritis affects the brain. The results of the study may explain the cognitive symptoms described as “brain fog.”
More than 1.3 million people in the United States live with rheumatoid arthritis.
Rheumatoid arthritis is an autoimmune disorder. In which the body’s immune system does not recognize the synovial fluid in the joints. And then attacks the fluid in the joints, causing chronic inflammation.
But can this chronic inflammation also affect the brain? And if so, how?
This question prompted researchers — co-led by Andrew Schrepf and Chelsea Kaplan, from the University of Michigan in Ann Arbor — to examine the brains of 54 people with rheumatoid arthritis.
Schrepf, a research investigator at Michigan Medicine’s Chronic Pain and Fatigue Research Center, explains the motivation for the study, the results of which have now been published in the journal Nature Communications.
He explains, “Even though it has been assumed for a long time that the inflammation we see in blood is impacting the brain, up until this study we didn’t know precisely where and how those changes in the brain were actually happening.”
Schrepf adds that the effects of inflammation are easier to understand when the illness is short-lived, such as in the case of the flu.
But he also notes that the researchers “wanted to understand what is happening in conditions where patients have inflammation for weeks, months, or years, such as in rheumatoid arthritis.”
Studying the brain in rheumatoid arthritis
Specifically, Schrepf and colleagues wanted to see how the peripheral inflammation of arthritis affects the structure and connectivity of the brain.
To this end, they used functional MRI and structural MRI to scan the brains of 54 participants aged 43–66. Brain scans were taken both at the beginning of the study and 6 months later.
The study participants had lived with rheumatoid arthritis for an average period ranging between 2.85 years and over 20 years.
“We took the levels of inflammation in their peripheral blood. As it a rheumatologist would do clinically to monitor the disease’s severity and how it’s being controlled,” Schrepf explains.
“Finding profound and consistent results in a couple areas of the brain that were becoming connected to several brain networks. We looked again 6 months later and saw similar patterns, this replication of results is not common in neuroimaging studies.”
Investigating how inflammation affects patterns of functional connectivity in more detail, researchers examined the connections between 264 brain regions.
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