Young children who undergo multiple procedures requiring anesthesia could be at higher risk for developing attention-deficit hyperactivity disorder (ADHD) later on, according to a new study published in the current issue of the journal Mayo Clinic Proceedings.
Researchers from the Mayo Clinic in Rochester, Minn. and Children's Hospital in Boston analyzed the medical records of more than 5,300 children previously enrolled in other studies. They found that children younger than two years old who underwent more than one procedure that called for anesthesia were more likely to develop ADHD.
But Dr. David Warner, a co-author and professor of anesthesiology at the Mayo Clinic, stressed that the study only found an association between the procedures performed on the children in the study and ADHD.
"We need to do more work to confirm whether this is really a problem in children or not," he said. "We can't exclude there is a problem, but we also haven't determined there is a problem."
The potential effects on the developing brain also remain unknown, he said. Previous studies on young rodents found a link between anesthesia exposure and problems with learning and memory. But while researchers are able to separate out the effects of anesthesia on animals by exposing them only to anesthesia, they cannot do the same in children, making it difficult to determine whether ADHD is related to the anesthetic drugs, to the specific procedures, or to other medical conditions.
"It's not normal for a one-year-old to have two surgeries before the age of two, so maybe there are some underlying conditions that leads them to have surgery," said Dr. Rod Eckenhoff, vice chair of research in the Department of Anesthesia and Critical Care at the University of Pennsylvania in Philadelphia. Eckenhoff was not involved with the Mayo Clinic research.
Prior research on children has also linked surgical procedures to learning disabilities, autism spectrum disorders in children and the risk of deteriorating brain function in the elderly.
In an editorial accompanying the study, Dr. Deborah Culley of Harvard Medical School in Boston wrote that the known benefits of surgery in infants and young children should outweigh an unproven risk.
"The decision to proceed with surgery with anesthesia in an infant is best made based on what is known about the indications for-- and benefits of -- the procedure and general anesthetic, rather than what is unknown but feared," she wrote. She also added that doctors should take certain precautions, such as minimizing how long an infant is exposed to anesthesia.
Eckenhoff said even though the relationship between surgical procedures that use anesthesia and ADHD is only associative right now, the findings should serve as a wake-up call to anesthesiologists; the drugs they use millions of times a year may have effects they never realized.
"(W)e need to start looking carefully," he said, "and think about trying to develop drugs that don't have the potential to have effects on the brain."