New research shows children who receive general anesthesia for surgery before the age of 4 often had diminished language comprehension, lower IQ and decreased gray matter density in parts of the brain.

The research team noted additional research is needed to determine the exact molecular effects anesthesia has on the brain, but hope their will help lead to the development of mitigating strategies for what could be a "dilemma" for children's health, Cincinnati Children's Hospital reported.  

"The ultimate goal of our laboratory and clinical research is to improve safety and outcomes in young children who have no choice but to undergo surgery with anesthesia to treat their serious health concerns," said Andreas Loepke, lead study author and an anesthesiologist in the Department of Anesthesiology at Cincinnati Children's. "We also have to better understand to what extent anesthetics and other factors contribute to learning abnormalities in children before making drastic changes to our current practice, which by all measures has become very safe."

Past studies have found widespread cell death, permanent deletion of neurons, and diminished brain function in rodents exposed to general anesthesia.  In the recent study, a team of researchers looked at 53 healthy participants of a language development study who were between the ages of 5 and 18 and had no history of surgery and compared their scores with those of participants in the same age range who had undergone surgery before the age of 4.

They found the average test scores for all 106 children in the study were within population norms, but the children who had been exposed to anesthesia before the age of 4 generally had lower comprehension and performance IQ scores than those who had not. The researchers also observed decreased language and IQ scores associated with lower gray matter density in the occipital cortex and cerebellum.

Past research has estimated the loss of one IQ point could decrease a person's lifetime earnings by about $18,000. If the potential loss of 5 to 6 IQ points observed in the study are factored in, this could meant the six million children who undergo surgery in the U.S. every year have a potential loss of lifetime earnings equal to about  $540 billion.

The study highlights the need to improve methods of administering anesthesia to children, and parents are urged to discuss potential risks with their pediatrician or surgeon.

"It is important to note that no surgeries are truly elective in young children," Loepke said. "Many surgical procedures early in life treat life-threatening conditions, avert serious health complications, or improve quality of life. These cannot be easily postponed or avoided."

The findings were published in a recent edition of the journal Pediatrics.