It’s been long known that many children with autism also have epilepsy or some form of seizure disorder. Not so well understood was the relationship between the two.

But a new Penn study suggests that early life seizures may switch on synapses in the brain that can lead to further development delays in children with autism and other intellectual disorders, including language and learning deficits.

Aggressively treating those seizures may keep those synapses “silent” and allow the brain to develop more normally. “We now have evidence that seizures appear to be worsening the developmental disorder, and when you block those seizures, you reverse that,” said senior author Frances Jensen, chair of neurology at Penn’s Perelman School of Medicine.

“It appears seizures may exacerbate features common in autism,” said Jensen, whose research conducted with colleagues from Harvard and Carleton University was published in the journal Cell Reports.

According to 2014 data from the Centers for Disease Control and Prevention, autism has a prevalence rate of 1 in 59 among 8-year-olds in 11 states surveyed, a 15 percent increase from 2012.

As many as 40 percent of children with autism and intellectual disabilities also have epilepsy, and about 35 percent of children who experience infantile spasms develop long-term intellectual disabilities, including autism, according to the researchers.

The findings build on what is known about brain development. During early childhood, the brain goes through so-called critical periods where synapses linked to language skills are activated gradually. But if the synapses are activated or “unsilenced” prematurely through seizures, they are less available for learning during those critical periods, the researchers said.

“Understanding the precise synaptic changes following seizures gives an opportunity to find treatments that can prevent this early ‘unsilencing,’ ” Jensen said. “The timing is important: We need to stop it right after the seizures and before a critical period of development in a child’s life so the brain can develop without any problems that may lead to future impairments.”

While many of these children may already be prescribed anti-epileptic medications to help prevent seizures, researchers are advocating for additional treatment following each individual seizure.