General anesthesia in early childhood and possible association with autism: a population-based matched cohort study

Structural basis for the inhibition of cystathionine-β-synthase by isoflurane and its role in anaesthesia-induced social dysfunction in mice

BACKGROUND

Anaesthesia has been shown to impair social functioning, but the underlying mechanisms remain largely unknown. The volatile anaesthetic isoflurane potentially disrupts the methionine cycle and trans-sulphuration pathway, contributing to social deficits. Cystathionine-β-synthase (CBS), a key enzyme in this pathway, might be targeted by isoflurane. We investigated the CBS-isoflurane interaction and its role in neuronal function and social behaviour.

METHODS

Mice aged 3-15 months were anaesthetised with 2 vol% isoflurane for 2 h, and social behaviours were tested 24 h after exposure. Alterations in neuronal activity were assessed using electrophysiological analysis in vivo. Pharmacological activators (S-adenosylmethionine [SAM]) or inhibitors (amino-oxyacetic acid [AOAA]), and adeno-associated virus (AAV) were used to modulate CBS activity. The binding site of isoflurane on CBS was determined using X-ray crystallography. A novel transgenic model with a point mutation knock-in was constructed to eliminate the CBS-isoflurane interaction.

RESULTS

Isoflurane inhibited CBS activity (by 0.35-fold [0.07] vs 1.00-fold [0.05]; P<0.001), leading to neuronal hypoactivity in the anterior cingulate cortex (ACC) and social impairments in adult and elderly mice. SAM, AOAA, and AAV interventions demonstrated a causal link. Structural and functional analysis identified the lysine 273 (K273) in CBS to be involved in isoflurane inhibition. CBS K273A knock-in mice exhibited increased CBS activity compared with wild-type littermates after isoflurane exposure (2.2-fold [0.22] vs 1.0-fold [0.28]; P<0.001), with successful alleviation of ACC neuronal hypoactivity and social dysfunction.

CONCLUSIONS

These findings reveal a crucial role for CBS inhibition by isoflurane in anaesthesia-induced social impairment.

Effects of Cohabitation on Neurodevelopmental Outcomes in Rats Discordant for Neonatal Exposure to Sevoflurane

Background

Having a sibling with autism spectrum disorder is a risk factor for autism spectrum disorder. We used a rat model in which the general anesthetic sevoflurane (SEVO) induces autism spectrum disorder-like neurodevelopmental abnormalities to test whether they can be transmitted via cohabitation.

Methods

Male rat pups from several litters were mixed and randomized to 3 new litter types: SEVO-exposed (SEVO), SEVO-unexposed (control), and equal numbers of SEVO-exposed and SEVO-unexposed (MIXED). After weaning, rats in experiment 1 were housed with littermates in SEVO, control, and MIXED (MIXED-exposed and MIXED-unexposed) pairs. In experiment 2, MIXED-exposed and MIXED-unexposed rats were paired with an unfamiliar naïve cagemate. Corticosterone levels, gene expression, central inflammatory markers (experiment 1), and behavior and corticosterone levels (experiment 2) were assessed in adulthood.

Results

In experiment 1, compared with control rats, SEVO rats exhibited abnormalities in the hypothalamic-pituitary-adrenal axis, inflammatory markers, oxytocin, arginine vasopressin, and DNA methylation systems. Almost all these measures in MIXED-exposed and MIXED-unexposed rats were statistically indistinguishable from and similar to those in SEVO or control rats, with most measures in MIXED rats being similar to those in SEVO rats. Experiment 2 showed that pairing with unfamiliar, naïve rats after weaning caused MIXED-unexposed and MIXED-exposed rats' behavior to be no different from that of control and SEVO rats, respectively; however, the 2 groups of MIXED rats also did not differ from each other.

Conclusions

These findings suggest that neurodevelopmental abnormalities can be transmitted to otherwise healthy individuals through interactions during cohabitation; however, subsequent pairing with unfamiliar, naïve cohabitants may weaken this interaction effect.

The Relationship between Early Exposure to General Anesthesia and Neurobehavioral Deficits

BACKGROUND

In contemporary medical practice, general anesthesia plays an essential role in pediatric surgical procedures. While modern anesthetic protocols have demonstrated safety and efficacy across various pathological conditions, concerns persist regarding the potential neurotoxic effects associated with early exposure to general anesthesia.

SUMMARY

Current research primarily examines the neurocognitive developmental impacts, with limited focus on neurobehavioral developmental disorders. This review presents a comprehensive analysis of clinical trial results related to five critical neurobehavioral developmental disorders: fine motor disability, attention-deficit hyperactivity disorder, impulse control disorders, autism spectrum disorder, and developmental coordination disorder. Furthermore, this review synthesizes insights from basic research on the potential toxicological mechanisms of general anesthetic agents that could influence clinical neurobehavioral changes. These findings provide valuable guidance for the prudent and safe utilization of anesthetic agents in pediatric patients.

KEY MESSAGES

This review explores the potential connections between general anesthesia and five neurobehavioral disorders, highlighting the importance of cautious anesthetic use in children in light of current research findings.

The Future of Social Media, Anesthesiology, and the Perioperative Physician

Social media has rapidly developed in the past decade to become a powerful and influential force for patients, physicians, health systems, and the academic community. While the use of social media in health care has produced many positive changes, such as rapid dissemination of information, crowd-sourced sharing of knowledge, learning, and social interaction, social media in health care has also negative effects. Recent examples of negative impacts of social media include rapid and unchecked information dissemination leading to patient misinformation and inadvertent reputational harm for health care professionals due to engaging in controversial topics on public platforms. Members of the anesthesiology community, like other medical specialties, have rapidly adopted social media at many different levels. However, most anesthesiologists, health systems, and academic communities have little education, preparation, and guidelines on optimizing the use of social media technology while minimizing the risks of social media. Anesthesiology has been and will continue to be impacted by the forces of technology and the cultural influences of social media for the foreseeable future. The purpose of this article was to examine the recent history of social media adoption in anesthesiology and perioperative medicine, understand the current impact of social media across our specialty, and consider how the future development of technology and evolving social and cultural dynamic influences of social media will have on anesthesiology over the next quarter century.

The Role of Neuroactive Steroids in Analgesia and Anesthesia: An Interesting Comeback?

Published evidence over the past few decades suggests that general anesthetics could be neurotoxins especially when administered at the extremes of age. The reported pathology is not only at the morphological level when examined in very young and aged brains, given that, importantly, newly developing evidence suggests a variety of behavioral impairments. Since anesthesia is unavoidable in certain clinical settings, we should consider the development of new anesthetics. A promising and safe solution could be a new family of anesthetics referred to as neuroactive steroids. In this review, we summarize the currently available evidence regarding their anesthetic and analgesic properties.

Unanswered questions of anesthesia neurotoxicity in the developing brain

PURPOSE OF REVIEW

This article reviews recent advances and controversies of developmental anesthesia neurotoxicity research with a special focus on the unanswered questions in the field both from clinical and preclinical perspectives.

RECENT FINDINGS

Observational cohort studies of prenatal and early childhood exposure to anesthesia have reported mixed evidence of an association with impaired neurodevelopment. Meta-analyses of currently available studies of early childhood exposure to anesthesia suggest that, while limited to no change in general intelligence can be detected, more subtle deficits in specific neurodevelopmental domains including behavior and executive function may be seen. Several studies have evaluated intraoperative blood pressure values and neurocognitive outcomes and have not found an association. Although many animal studies have been performed, taking into consideration other peri-operative exposures such as pain and inflammation may help with translation of results from animal models to humans.

SUMMARY

Advances have been made in the field of developmental anesthetic neurotoxicity over the past few years, including the recognition that anesthetic exposure is associated with deficits in certain cognitive domains but not others. Although the most important question of whether anesthetic agents actually cause long-term neurodevelopmental effects in children has still not been answered, results from recent studies will guide further studies necessary to inform clinical decision-making in children.

Early exposure to general anaesthesia and increasing trends in developmental behavioural impairments: is there a link?

Over the past two decades there has been an increase in reports of attention deficit-hyperactivity disorder and perhaps autism spectrum disorder that appear to coincide with a substantial number of general anaesthesia interventions during early stages of human brain development. Is there a link between anaesthesia exposure and neurocognitive effects considering the growing body of evidence in numerous animal species, including humans, that suggests long-lasting socio-affective behavioural impairments after early exposure to general anaesthesia? Could routinely used general anaesthetics contribute as environmental toxins? Here we present the case that this notion is worthy of further consideration.