28 January 2015. Although drugs must be carefully tested and shown to be safe before they can be approved for use, pre-market testing may not secure that pharmaceuticals are brain safe – especially anesthetics used in children. Before an operation, anesthesia puts the patient to sleep and removes pain perception by blocking certain brain functions. Could this interference result in longer-term effects? A variety of animal models suggest that the answer is yes, but the conclusions from clinical studies are unclear.
As early development is likely the most vulnerable life stage regarding anesthetic agents, studies have been conducted in children undergoing surgical procedures, e.g., for congenital malformations. While some studies have suggested developmental delays in operated children, the question is who should these children be compared to? Could it be that the underlying diagnosis was the reason for any delay? This problem is not easily solved, as anesthesia is not used in children unless there is a valid indication, such as necessary surgery.
A similar conundrum exists for brain drain risks from environmental chemicals. We are all exposed to them, but their effects on brain development are poorly known – controlled studies with different treatment groups would likely be unethical, and unexposed comparison groups may be difficult to find. However, the absence of documentation should of course not be understood as evidence that no risk is present.
To put the problem in perspective, 1.5 million US infants under 12 months receive anesthesia every year, and the total for children below 15 years is 6 million. For comparison, the U.S.Centers for Disease Control estimate that 0.5 million children aged 1-5 years have elevated blood-lead concentrations (above 50 micrograms per liter). A slightly higher number of children are born every year with elevated exposure to methylmercury (more than 0.58 micrograms of mercury per gram of maternal hair), and hundreds of thousands are exposed to potentially toxic levels pesticides and other known or suspected brain drainers. Now that the US Food and Drug Administration is actively exploring ways to protect developing brains against brain-toxic anesthetics, hopefully more protective approaches can be developed for chemicals in general.