A new study has shown that Rhesus macaques infants repeatedly exposed to anesthesia displayed persistent anxiety-linked behaviors during their later life in response to social stress. The study is published in the British Journal of Anaesthesia.
Previous studies have shown a possible association between multiple exposures to anesthesia and learning problems. The cause-and-effect relationship hasn’t bee clear because children who need surgery may have underlying medical issues. Also, research in other animal models, such as rodents, has shown anesthesia exposure early in life can lead to cell death in the brain and cognitive impairments.
In the latest study researchers sought to determine whether non-surgical exposure to sevoflurane, an inhaled anesthetic commonly used with children, could lead to cognitive and behavioral alterations in a nonhuman primate (NHP) model. A translational animal model for this type of study provides information for consideration in the human clinical population.
Researchers exposed rhesus macaques three times during the first six weeks of life to sevoflurane for four hours each time. Animals’ behavioral responses to a mild stress (an unfamiliar human) were recorded at one and two years of age. In these situations, animals exposed to anesthesia displayed increased behaviors such as scratching, self-touching and self-grooming, which could be interpreted as fidgeting.
The team is continuing to assess the effects of early anesthesia exposure on behavior at older ages.
In human children, alterations in anxiety levels could impact learning in school or test scores, although existing evidence is not so fine-grained. Epidemiological studies find increased incidence of learning disabilities and ADHD in kids with more than one exposure before the age of 3-4 years. The monkey studies are consistent with these reports and provide an opportunity to understand the mechanisms of anesthesia-induced cognitive changes, as well as show that the effects in humans may at least be partially due to anesthesia itself rather than surgery or an underlying condition that requires surgery, Raper says.