General anesthesia may be to blame for lower IQ and language skills in children who underwent surgery at a young age, a new study suggests.

Researchers from Cincinnati’s Children’s Hospital found children, aged four and younger, who received general anesthesia for surgery had diminished language comprehension and lower IQ scores when compared to their peers.

The study compared the scores of 53 healthy participants, ages 5 to 18 years, with no history of surgery, to test scores of 53 children of the same age range who had undergone surgery before the age of four.

The children were also compared and matched by gender and socioeconomic status.

Results showed that children exposed to anesthesia scored significantly lower in listening comprehension and performance IQ.

Researchers noted however, that scores were within population norms regardless of surgery history.

The study also looked at brain structure, and found that decreased language and IQ scores were associated with lower gray matter density in two parts: the occipital cortex (lobes at the back of the brain) and the cerebellum, which is responsible for motor control.

The children were assessed using oral and written language scales, as well as the Wechsler Intelligence Scale. Brain structures were examined using MRI scans.

The study follows previous research that showed widespread cell death, permanent deletion of neurons, and neurocognitive impairment in laboratory rats after exposure to general anesthesia.

Lead study author Dr. Andreas Loepke said, in light of these studies, there are growing health concerns for children undergoing anesthesia.

“Numerous studies have found that there’s widespread neuronal cell death and altered brain structure as well as long-term learning impairment following anesthetic exposure early in life,” Loepke told CTV’s Canada AM on Monday.

Researchers are “not entirely sure” why anesthetics have this effect on children in particular, Loepke said, but studies on animals have found that young, vulnerable neurons are “tricked” by anesthetics to go into “cell suicide.”

“That’s a normal process for the normal brain, but anesthesia exaggerates this process, and we believe that younger children have more neurons that are young and vulnerable to this process,” said Loepke, who is a professor of Clinical Anesthesia and Pediatrics at the University of Cincinnati.

Despite the major safety concern, Loepke says he doesn’t recommend changes at this point.

“These surgeries can’t be postponed often times because surgeries need to be performed to save patient’s lives and to prevent major health problems,” Loepke said. “So sometimes it’s more important to take care of these than those theoretical concerns about anesthesia.”