For the first three years of his life, Rene Craft's son, Jackson, communicated primarily through screaming tantrums. He never spoke. He didn't point to things. He didn't make eye contact. He had the classic signs of severe autism.
Then a couple of years ago, Jackson got sick. His mother, Rene Craft, says he was running a high fever.
"He was lying in our bed, and he was recovering," Craft says. "And he said out of the blue, 'I like the sheets, Daddy. They're really comfortable.' And then later that day he looked out the window and he said, 'Oh, it's raining, and squirrels eat nuts."
Craft says that she and her husband got a brief glimpse of a son who had been locked in his own world of autism. Then the fever went away, and so did Jackson's improvement.
Craft isn't the first parent to notice the so-called "fever effect." Autism researchers have been hearing reports about it for decades.
Now a team from the Kennedy Krieger Institute in Baltimore has done a study that suggests the fever effect is real.
Laura Curran, Ph.D., is the lead author of the study, which appears in the current issue of the journal Pediatrics.
"We did find fewer autistic-like behaviors when kids had fevers," she says. "And as the fever disappeared, their autistic behaviors returned."
That wasn't true for every child. And the study included just 30 children, and relied on parents to fill out detailed checklists about each child's behavior.
Even so, Curran says it looks like parents have been right all along. She says she's not surprised.
"As a mother myself, I know no one knows their children better than the parents," she says. "And we've been hearing about these anecdotes for many, many years."
Now the question for researchers is how fever affects autism.
Dr. Andy Zimmerman of Kennedy Krieger says the answer probably involves the connections between brain cells — which many researcher believe is one place things go wrong in autism.
Zimmerman says that it's not the rise in a child's temperature that makes the difference. But it may be that brain connections work better in the presence of small proteins called cytokines that are produced by the immune system.
"We'd like to know what those cytokines are in children with autism when they get fevers, to see if one or more of these cytokines might be unusually increased," he says.
That might lead to a treatment that could mimic the beneficial effects of fever without actually making a child sick.
Craft believes researchers will find an answer, and it will help her son.
She says she has noticed that every time Jackson gets a high fever, he undergoes a dramatic change. He may ask to play a game, or make eye contact, or stop biting his hands until they bleed.
"Jackson runs into furniture with his head when he's upset or I question him," Craft says. "When he has a fever, those behaviors disappear."
Craft says she plans to enroll her son in a new study at Kennedy Krieger that will try to explain the fever effect.
. "There is something occurring in his brain that he needs, that he gets when he has a fever," Craft says. "I don't know what it is. That's for the doctors to figure out. But he's in there. He's waiting to come out."