Anesthesia Before Age 4 May Affect IQ, Language Comprehension

Children who underwent surgery with general anesthesia before 4 years of age later scored lower on tests for listening comprehension and performance IQ than children who did not undergo anesthesia, a study published in June’s Pediatrics has revealed.

Although the researchers failed to find the kind of measurable neuronal deletion seen in animal studies of anesthesia use during brain development, authors Barynia Backeljauw, BS, from Cincinnati Children’s Hospital Medical Center in Ohio, and colleagues note the lower performance IQ and language comprehension scores associated with lower grey matter density in the occipital cortex and cerebellum.

“The present findings suggest that general anesthesia for a surgical procedure in early childhood may be associated with long-term diminution of language abilities and cognition, as well as regional volumetric alterations in brain structure,” the authors write.

The researchers looked at healthy children who completed a language study from age 5 to 18 years, comparing 53 children who had undergone surgery with anesthesia before age 4 years with 53 children matched for age, handedness, sex, and socioeconomic status who lacked general anesthesia exposure.

Children who had been exposed to anesthesia had scores for listening comprehension that were, on average, 6 points lower than those of unexposed children (adjusted P = .039) and had IQ performance scores, on average, 6.4 points lower than unexposed children (adjusted P = .039). Test scores fell within population norms for both groups, regardless of past anesthesia exposure.

The authors note that the study could not prove causation: There was no way to determine whether neurocognitive differences arose from other sources, such as surgery itself, including associated inflammation and pain, or the underlying indication for surgery.

The authors write that the loss of even a single IQ point can decrease an individual’s lifetime earnings by $18,000. A 5- to 6-point decline, as seen in this study, could result in a loss of more than $540 billion among the 6 million children who undergo surgery annually in the United States, the authors write.

“Moreover, a potential population-wide downward shift of the IQ distribution could result in an increase in the number of very low performers (IQ<70) and concomitant reduction in the number of high performers, with dramatic societal implications.”

“These provocative findings warrant additional research efforts to better define human applicability of animal data, to delineate the phenomenon’s mechanisms, and to devise mitigating strategies for this potential dilemma for child health,” the authors conclude.