One Boston lab is scrutinizing brain waves of infants to detect very early signs of autism. Another is studying how fevers in children with autism may be linked to a dramatic but temporary reduction in symptoms. Others are measuring how the brains of people with the developmental disorder process information differently than those without the condition.

Researchers across the region, who’ve spent years deciphering autism, say Health and Human Services Secretary Robert F. Kennedy Jr.’s pledge to determine what causes autism by September is not only wildly unrealistic, it may undermine decades of science into a complex condition that affects millions of children in the United States.

The mounting uneasiness comes as the number of children diagnosed with autism, which affects how people communicate and interact with the world, continues to rise. The latest numbers, released Tuesday by the Centers for Disease Control and Prevention, show one in 31 children aged 8 years old were diagnosed with autism spectrum disorder in 2022, up from one in 36 two years earlier. (Autism spectrum disorder refers to the broader range of conditions associated with the brain condition.)

The CDC report noted the increased prevalence is attributed to improved access to screening, particularly among “previously underserved groups,” such as children of color and those from lower income communities.

Kennedy, a longtime vaccine critic, has for years pushed the debunked claim that routine childhood vaccines cause autism. Last week, during a Trump administration cabinet meeting, he announced his plan to devote hundreds of scientists to his new mission and tap David Geier, who has long claimed a link between vaccines and autism, to lead it.

The Health and Human Services Department did not return a request for comment. But on Wednesday, Kennedy pledged at a news conference that “we’re going to follow the science no matter what it says and we will have some of the answers by September.”

He reiterated his long-held stance that autism is caused by environmental toxins, such as pesticides, pollution and even ultrasounds but did not name specific vaccines, as he has in the past. Yet he contradicted the conclusion of his agency’s own report from a day earlier by repeatedly referring to the rise in cases as an epidemic. He also criticized scientists and “mainstream media” for their “epidemic denial.”

Kennedy said his new autism research panel would be staffed with credible scientists and that it would issue traditional research grants to study autism’s cause.

“We’re going to remove the taboo. People will know they can research and they can follow the science no matter what it says, without any kind of fear that they’re going to be censored, that they’re going to be gaslighted, that they’re going to be silenced, that they’re going to be defunded,” he said.

But even before Kennedy spoke, researchers said they doubted the mission would be credible.

“I am concerned that the outcome is a foregone conclusion, and that is the worst way to do science,” said Mriganka Sur, a professor at Massachusetts Institute of Technology and director of the Simons Center for the Social Brain, which studies autism.

Sur compared Kennedy’s championing of a debunked theory of autism, coupled with the Trump administration’s sweeping termination of hundreds of research grants, to a dangerous slide into “Lysenkoism,” a reference to the 1940’s era when thousands of scientists in the Soviet Union were dismissed, imprisoned, or executed for not adhering to a political campaign that discredited genetics.

“All the decades of work and research that the National Institutes of Health has built up is being just summarily destroyed,” he said.

Scientific consensus has long held that genetics plays a large role in autism; that some people are more at risk of the disorder because of their genes.

“There are certain genes we know cause autism, and there are other genes that may be linked to autism but don’t necessarily always cause it, and there may be other combinations of genes that we have yet to find,” said Dr. Ann Neumeyer, medical director of the Lurie Center for Autism at Massachusetts General Hospital, and an associate neurology professor at Harvard Medical School.

Research has linked a number of factors before and during birth to a higher risk of autism in children, including: prenatal exposure to air pollution or certain pesticides, advanced parental age during conception, and even prenatal exposure to fever and inflammation.

The link between fever, inflammation, and autism has fascinated scientists, as parents report that some children with the disorder show temporary improvements in their ability to speak and socialize after having a fever.

Neumeyer and colleagues from MIT and Harvard Medical School are studying children with autism to see if they can find signs of changes in their blood after a fever that might provide answers.

“We are trying to better characterize what’s happening during a fever that’s causing this improvement,” Neumeyer said. “If there’s a chemical [produced during a fever] that can improve autism transiently, maybe we could devise a treatment that would help people in the future.”

Autism is a wily disorder, complex in its roots and evasive to researchers searching for effective medications to ease symptoms.

“Probably there are many different causes of autism, in the same way there are many different reasons that people get heart disease,” Neumeyer said.

Gloria Choi, an associate brain and cognitive sciences professor at MIT who is collaborating with Neumeyer, said scientists believe it’s not the fever itself that may be positively affecting children with autism, but molecules produced by the body’s immune system that can be activated during a fever. Her work with mice found that, in some cases of infection, an immune molecule is released that can suppress a region in the brain that has previously been linked to social behavioral deficits in mice.

“We are coming to realize more and more that the brain is not a stand alone organ,” Choi said. “It’s influenced by many things in your body, many other systems and organs. People are coming to recognize the immune system has such a profound influence on how the brain functions.”

At Boston University, Helen Tager-Flusberg, director of the Center for Autism Research Excellence, is working with infants and uncovering signs that autism can be pinpointed in a child long before they start speaking. Using a device known as an EEG, which can read the brain’s electrical activity, they compare the brain signals of infants whose older siblings have been diagnosed with autism to those whose siblings do not have the disorder.

“You pick up brain activity while the baby is sitting quietly on mom’s lap,” Tager-Flusberg said.

The scientists then follow the children for two to three years until they are old enough for a comprehensive evaluation and diagnosis to determine whether they have autism.

“We can see differences in the brain signals in the first six months of life, long before babies receive [most] vaccinations, signals that distinguish those babies who end up with autism,” she said.

The team is still studying the data but believe it shows that even in these earliest months, the brains of infants with autism are processing information differently than those without the disorder.

Tager-Flusberg’s team is part of a consortium of scientists, stretching from the U.S. to the UK, studying infants’ brain waves, a project that has included thousands of babies over more than a decade. Given the years of research devoted to untangling autism, she said she doubts RFK, Jr. and his new team will be able to credibly determine the cause of autism by September, as he has vowed.

“They can’t possibly collect all the data they would need in that time,” she said. “It’s completely infeasible.”

Kay Lazar can be reached at kay.lazar@globe.com Follow her @GlobeKayLazar.