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

Study of patients with chronic fatigue 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 intense dizziness, fatigue and memory problems.

That was almost a decade ago, and ever since, she’s suffered from a 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 almost every day.

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

The disease also “messed me up cognitively,” she said. “I can’t read something and understand it very well, I can’t remember new things. It’s a bit like being in a state of uncertainty. That’s how I describe it, lost in limbo.

Seven years ago, the National Institutes of Health began a study of ME/CFS patients, and Ms. Caldwell became one of 17 participants who engaged in a series of tests and evaluations of their blood, their body and their brain.

Results of the studypublished 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 participants in good health under study.

Medical experts said that although the study was only a snapshot of a small number of patients, it was useful, in part because ME/CFS has long been dismissed or misdiagnosed. The results confirm that “it’s biological, not psychological,” said Dr. Avindra Nath, head of the department 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 include symptoms similar or identical to those of ME/CFS. Although study participants were recruited before the pandemic, all had a type of ME/CFS preceded by infection, just as Covid is preceded by coronavirus infection.

“Whatever we learn from ME/CFS will benefit ME/CFS patients, and whatever we learn from ME/CFS will benefit ME/CFS patients, I think,” said Dr. Nath, who said the infections experienced by the study patients 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 reviewer of the study for the newspaper. “They found 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 continue fighting,” he said. he declares.

Dr. Nath said his theory is that in both long-term and post-infectious ME/CFS, “you either have pieces of that pathogen that stay and drive this thing,” or “the pathogen disappeared, but whatever it did for the immune system, it simply never stabilized 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 reduced activation – whereas, in people in good health, she showed increased activation.

This area of ​​the brain, the right temporoparietal junction, is involved in “telling the legs to move, the mouth to open and eat – it kind of means to do something,” Dr. Komaroff said. . “When it doesn’t turn on properly, it’s more difficult to get the body to make that effort,” he continued, adding that the NIH researchers “speculate that the chronic immune stimulation they have found and the changes in the gut microbiome that they found could lead to these brain changes, which then lead to symptoms.

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

The disease can also develop in people who have not been infected. And while ME/CFS is often characterized by a severe loss of energy after physical or cognitive exertion (a phenomenon called post-exertion malaise), study participants had to be functional enough to undergo an intense assessment for days of visits to the NIH in Maryland.

“They selected rather healthy patients,” said Dr. Carmen Scheibenbogen, 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 results, it’s just disappointing because it 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, noted that in the years since their participation, four of the 17 patients “spontaneously recovered” from the disease, which she said is “not typical of ME/CFS”.

She and Dr. Scheibenbogen also pointed out that the study did not find medical signatures of the disease documented by other research. For example, the study did not find that patients performed worse on cognitive tests or had neuroinflammation.

“These are well-established pathologies and really central to ME/CFS,” Ms. Pollack said, adding “so it doesn’t address everything and contradicts some of the things we know.”

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

Experts said the study, which is the first detailed NIH study of ME/CFS, should be considered only a step in understanding the disease, its severity and potential cures. “We need to 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 15 on a 100-point scale of physical functioning and 6.25 on a scale “vitality” of 100 points measuring energy level and fatigue. and feelings of well-being.

Her main hope for this study, she says, is that it will encourage doctors and others to recognize ME/CFS and take it seriously.

“We’re kind of on the cusp of trying to get our heads around it, so this study is a big deal,” she said. “For so long I was criticized, dismissed, invalidated, belittled,” she added, “so the validation is huge for me.”

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Eric D. Eilerman

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