Rheumatoid arthritis is a chronic inflammatory and autoimmune condition that can affect a person’s joints and the rest of their body, inducing fatigue, sleep and creating cognitive difficulties.
There has been limited understanding of how inflammation affects the brain for people with conditions, like rheumatoid arthritis (RA). Researchers are starting to focus in on that topic and they’ve published their examination of the issue in a new study in Nature Communications.
“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.” says Andrew Schrepf, Ph.D., a research investigator at Michigan Medicine’s Chronic Pain and Fatigue Research Center and one of the lead authors of the study.
Schrepf says the effects of inflammation are more understood in short-term illnesses, but the same can’t be said for chronic conditions.
“When a person becomes sick with the flu, for example, they begin to show symptoms of the inflammation happening in their body, such as feeling lethargic and being unable to control their body temperature,” he says. “We wanted to understand what is happening in conditions where patients have inflammation for weeks, months or years, such as in rheumatoid arthritis.”
Using functional and structural neuroimaging of the data set at baseline and six months, the research team examined whether higher levels of peripheral inflammation were associated with brain connectivity and structure.
“We took the levels of inflammation in their peripheral blood, just as it would be done clinically by a rheumatologist to monitor the severity of their disease and how it’s being controlled,” Schrepf says. “We found profound and consistent results in a couple areas of the brain that were becoming connected to several brain networks. We then looked again six months later and saw similar patterns, and this replication of results is not that common in neuroimaging studies.”
Co-first author Chelsea Kaplan, Ph.D., an anesthesiology research fellow at Michigan Medicine, then examined the functional connectivity of 264 regions of the brain and identified increased connectivity patterns in patients experiencing heightened levels of inflammation.
“In a graph theoretical analysis across the whole brain network, and correlating that with levels of inflammation, we saw a lot of convergence across methods and time points for the amount of connectivity in the inferior parietal lobule and medial prefrontal cortex,” Kaplan says.
“This showed us that the brain doesn’t operate in isolation. It also demonstrated how inflammation we measure in the periphery may be actually altering functional connections in the brain and playing a role in some of the cognitive symptoms we see in rheumatoid arthritis.”
While the data support the idea that rheumatoid arthritis inflammation targets the brain and not just the joints, researchers pointed out additional research is needed on the correlation.