Study of patients with chronic fatigue condition may offer clues to long Covid

Jennifer Caldwell was active and energetic, working two jobs and caring for her daughter and parents, when she developed a bacterial infection that was followed by severe dizziness, fatigue and memory problems.

That was almost a decade ago, and since then he has battled the condition known as myalgic encephalomyelitis/chronic fatigue syndrome, or ME/CFS. Ms. Caldwell, 56, of Hillsborough, North Carolina, said she went from being able to ski, dance and work two jobs as a clinical research coordinator and caterer to having to stay in bed most of the time. of the day.

“I haven’t felt well since and I haven’t worked a day since,” said Ms. Caldwell, whose symptoms include severe dizziness when her legs are not elevated.

The condition has also “cognitively ruined me,” he said. “I can’t read something or understand it very well, I can’t remember new things. It’s like being in a state of limbo. “That’s how I describe it, lost in limbo.”

Seven years ago, the National Institutes of Health began a study of patients with ME/CFS, and Ms. Caldwell became one of 17 participants who took part in a series of tests and evaluations of their blood, bodies and brains.

Findings of the studywhich was published Wednesday in the journal Nature Communications, showed notable physiological differences in the immune system, cardiorespiratory function, gut microbiome, and brain activity of ME/CFS patients compared to a group of 21 healthy study participants.

Medical experts said that although the study was a snapshot of a small number of patients, it was valuable, in part because ME/CFS has long been dismissed or misdiagnosed. The findings confirm that “it’s biological, not psychological,” said Dr. Avindra Nath, chief of nervous system infections at the National Institute of Neurological Disorders and Stroke, who led the study.

The findings may have implications for patients with long Covid, which often includes symptoms similar or identical to those of ME/CFS. Although the study participants were recruited before the pandemic, they all had a type of ME/CFS preceded by an infection, in the same way that Covid is preceded by a coronavirus infection.

“Everything we learn from ME/CFS will benefit long Covid patients, and I think everything we learn from long Covid will benefit ME/CFS patients,” said Dr. Nath, who said the infections experienced by The patients in the study varied. (None had Lyme disease; Ms. Caldwell’s infection was C. diff.)

Differences in the immune system were among the clearest findings, said Dr. Anthony Komaroff, a professor of medicine at Harvard Medical School who was not involved in the research but served as a study reviewer for the journal. “They found a chronic activation of the immune system, as if the immune system was engaged in a long war against a foreign microbe, a war that it could not completely win and therefore had to keep fighting,” he said.

Dr. Nath said his theory is that, in both post-infectious ME/CFS and long Covid, “either there are bits of that pathogen stuck together and driving this thing” or “the pathogen is gone, but whatever “The immune system never calmed down again.”

Another distinctive finding was that, when participants were asked to perform tasks measuring their grip strength, a part of their brain involved in coordinating and directing actions showed decreased activation, while, in healthy people, it showed decreased activation. increased.

That area of ​​the brain, the right temporal-parietal junction, is involved in “telling the legs to move, telling the mouth to open and eat; It kind of says do something,” Dr. Komaroff said. “When it’s not turned on properly, it’s harder to get the body to make that effort,” he continued, adding that the NIH researchers “speculate that the chronic immune stimulation they found and the changes in the gut microbiome they found could lead to these brain changes, which then lead to symptoms.”

Experts cautioned that the results of the small study may not reflect the experience of many people with ME/CFS.

The condition can also develop in people who have not experienced infections. And although ME/CFS is often characterized by severe energy depletion after physical or cognitive exertion (a phenomenon called post-exertional malaise), study participants had to be functional enough to undergo intense testing. during visiting days at the NIH in Maryland.

“They selected fairly healthy patients,” said Dr. Carmen Scheibenbogen, a professor of immunology at the Institute of Medical Immunology at the Charité hospital in Berlin, who was not involved in the study. “I think there are a lot of interesting findings, but it’s disappointing because this was a very important approach and they selected patients who are not very representative.”

Beth Pollack, a research scientist at the Massachusetts Institute of Technology, said that in the years after they participated, four of the 17 patients “spontaneously recovered” from the condition, which she said is “not typical of ME/CFS.” .

Both she and Dr. Scheibenbogen also noted that the study did not find some medical signatures of the condition that have been documented by other research. For example, it did not find that patients performed worse on cognitive tests or had neuroinflammation.

“These are well-established pathologies and really fundamental to ME/CFS,” Ms. Pollack said, adding “so this didn’t address everything and contradicted some things we know.”

Dr. Scheibenbogen said the most important findings are that the condition is due to a dysregulation of the immune system and that researchers clearly state that it is a physiological condition “not a psychosomatic disease.”

Experts said the study, which is the NIH’s first detailed look at ME/CFS, should be considered just one step toward understanding the condition, its severity and its potential remedies. “We must move the field toward treatment research,” Ms. Pollack said.

For Ms. Caldwell, some aspects of the experience as a study participant were sobering, such as when she scored a 15 on a 100-point scale of physical functioning and a 6.25 on a 100-point “vitality” scale that measures energy level, fatigue. and feelings of well-being.

His main hope for the study, he said, is that it encourages doctors and others to recognize ME/CFS and take it seriously.

“We’re on the verge of trying to be understood, so this study is very important,” he said. “I’ve been criticized, dismissed, invalidated and belittled for so long,” she added, “so the validation is huge for me.”