A recent study indicates that infants, under 3 years old, exposed to at least two general anesthesia procedures might have a higher risk of developing attention deficit hyperactivity disorder (ADHD).

The study was published this month in the journal Mayo Clinic Proceedings.

For the research, the Mayo Clinic scientists processed the data from a previous epidemiological study, that involved children born between 1976 and 1982 in Rochester, Minnesota, and identified those with learning disabilities or ADHD. There were 341 children younger than 19 with ADHD

Researchers looked for exposure to surgery and anesthesia before age 3 in the medical records of the Rochester Epidemiology Project, a decades-long database of all patient care in Olmsted County, Minnesota.

ADHD appeared in 7.3% of the children with no exposure to anesthesia and surgery, and the percentage in the children with one exposure to anesthesia and surgery was around 11.

“With Cesarean section with a general anesthetic, only a single anesthetic, we didn’t find any effect,” said study author Dr. Juraj Sprung, professor of anesthesiology at the Mayo Clinic.

Multiple general anesthesia exposures in infants under 3 might be associated with ADHD.

When children had at least two exposures to anesthesia and surgery, the percentage of ADHD rose to 17.9.

The scientists made adjustments for other factors (gestational age, sex, birth weight, co-morbid conditions, maternal age and education), but the rate of ADHD was still high.

These results may not be applicable to all racial or ethnic groups.

“The population in 1976 and 1982 was mostly white/Caucasian here in Minnesota,” said Dr. Juraj Sprung.

A previous research published in Pediatrics in November 2011, suggested an association between early multiple anesthesia exposures and learning disabilities in language, reading, and math. The study was performed by the same team.

There were animal studies that showed how anesthetics could affect the brain. Rats had damages in the cortical areas of the brains and became hyperactive after anesthesia. The abilities to perform tasks involving executive function were affected in monkeys exposed to ketamine for 24 hours as new-born.

However, it is important to take in consideration the influences of both procedures (anesthesia and surgery), as well as other factors that may lead to ADHD.

“Essentially, we did an observational study and we examined whether there is association with exposure to anesthesia, but not only to anesthesia,” said Dr. Juraj Sprung.

“This is an observational study. A wide range of other factors might be responsible for the higher frequency of ADHD in children with multiple exposures. The findings certainly do suggest that further investigation into this area is warranted, and investigators at Mayo Clinic and elsewhere are actively pursuing these studies,” said study author Dr. David Warner, Mayo Clinic pediatric anesthesiologist.

This study does not suggest that parents should avoid surgery for their infants (as a method to prevent ADHD), if the surgery is needed.

“At the present time, we shouldn’t make any recommendations based on the study, to do or don’t do the surgery. If you need the surgery, if you need the procedure, you certainly should go for it. What I would personally say: If it’s the type of surgery, the type of procedure that can wait, maybe it’s better to wait,” said Dr. Juraj Sprung.

ADHD appears in around 3-5% of children world wide and it is diagnosed in about 2-16% of children over 6 years old. It is a chronic disorder and almost half of those diagnosed in childhood have symptoms into adulthood. Around 4.7 percent of American adults have ADHD, it is estimated. Genetic and environmental factors are implicated in the development of this disorder. ADHD impede attention and focus, and includes restless and impulsive behavior.