This post has been updated.

The National Institutes of Health announced a new initiative Thursday to find the cause and a treatment for chronic fatigue syndrome, the mysterious, debilitating condition that disables many of its more than 1 million Americans who have it.

NIH Director Francis S. Collins said in an interview that medicine “desperately needs some new ideas” in the fight against the syndrome and the closely related neurological disorder myalgic encephalomyelitis. At the moment, there is no test, cause or treatment for the condition, which causes overwhelming, often disabling fatigue in more than a quarter of the people who have the disorder.

“There’s something going on here, and we ought to be able to come up with an answer with the tools we have,” Collins said.

Collins said the agency will move forward on two fronts. It will launch research at the NIH Clinical Center to intensively study a small number of individuals who have the disorder and will revive a working group focused on encouraging more research on the disorder outside of NIH. But no budget for the efforts has been developed yet, Collins said.

In February, the Institute of Medicine, an arm of the National Academy of Sciences, declared the syndrome a “serious, debilitating” physical disorder — not a psychological illness — in the hope of ending lingering beliefs that the condition was psychosomatic.

Other symptoms include joint and muscle pain, headaches, cognitive difficulties and problems with the immune and neurological systems. It often strikes after a flulike illness or other infection.

NIH spending on the disorder has languished near the bottom of the research agency’s priorities. In July, Brian Vastag, a former reporter for The Washington Post who has the disorder, wrote passionately of the need for additional NIH research.

Carol Head, president of the advocacy group Solve ME/CFS Initiative, said after the NIH announcement that “we are thrilled. This is a disease that has been neglected by the federal government, frankly, for decades.”

Head said that there is no doubt funding for research into the condition would have to increase substantially under the plan outlined by Collins, though she said her group looks forward to knowing how much will be spent.

Nevertheless, she said, “we think the steps that were taken . . . clearly indicate a sea change in the NIH’s commitment to this illness. And from everything we’ve heard, it’s coming from the top, from Dr. Collins.”

Collins said that in recent years, research had focused on the idea that the syndrome was caused by a mouse retrovirus, which proved untrue, but may have halted other promising areas of inquiry. The goal now is to “recruit some new bright ideas and idea generators” to the effort, he said.

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