A study carried out in mice finds that a common general anesthetic called isoflurane significantly interferes with the growth of neurons in the developing brain. These worrying findings back up a raft of earlier studies. Share on Pinterest Could general anesthetics alter brain development in infants? General anesthetics are used on hundreds of thousands of children each year in the United States. But over recent years, some concerns have been raised regarding this. So much so that in April 2017, the U.S. Food and Drug Administration (FDA) warned of potential risks to developing brains. They write that “repeated or lengthy use of general anesthetic and sedation drugs […] in children younger than 3 years or in pregnant women during their third trimester may affect the development of children’s brains.” The warning comes following studies that have hinted at long-term cognitive deficits in children following anesthesia. For instance, retrospective studies found that children who underwent surgery performed worse in language and cognitive tests, and saw an increase in Medicaid billing codes relevant to learning disorders.

General anesthesia and the developing brain In itself, the earlier studies do not prove a direct link. When a child undergoes surgery, there must be an underlying medical condition, and, of course, the surgical procedure itself could be to blame. There are other factors that might also play a role, such as parental stress. Beyond the retrospective human studies, there is a growing body of animal research that has come to similar conclusions. For instance, a study published in 2015 investigating repeated anesthetic exposure to infant rhesus monkeys found an increased frequency of anxiety-related behaviors at the age of 6 months. Recently, a team of researchers set out to understand what might be going on in the brain to produce these cognitive changes in infants. To this end, they used a mouse model and the general anesthetic isoflurane. The group was led by Eunchai Kang and Dr. David Mintz, both of the Johns Hopkins School of Medicine in Baltimore, MD, and their findings are published this week in PLOS Biology. Isoflurane was first approved for use in the U.S. in 1979. It is regularly used in children and is generally considered safe and effective. The researchers were specifically interested in charting its impact on the dentate gyrus, a part of the hippocampus. This region of the brain is vital for learning and the formation of new memories. The hippocampus houses a large population of neurons that develop in the period shortly after birth. Fifteen-day-old mice were exposed to 4-hour doses of isoflurane, equivalent to the doses used in children. The development of their hippocampus was subsequently recorded.