June 20, 2024

Childhood General Anesthesia and Subsequent Diagnoses of ADHD

In December 2016, the U.S. Food and Drug Administration (FDA) warned “that repeated or lengthy use of general anesthetic and sedation drugs during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester may affect the development of children’s brains.” The FDA adds, “Health care professionals should balance the benefits of appropriate anesthesia against the potential risks, especially for procedures lasting longer than 3 hours or if multiple procedures are required in children under 3 years,” and “Studies in pregnant and young animals have shown that using these drugs for more than 3 hours caused widespread loss of brain nerve cells.”

That raises a concern that such exposure could lead to increased risk of psychiatric disorders, including ADHD.

Noting “There are inconsistent reports regarding the association between general anesthesia and adverse neurodevelopmental and behavioral disorders in children,” a South Korean study team conducted a nationwide population study to explore possible associations through the country’s single-payer health insurance database that covers roughly 97% of all residents.

The team looked at the cohort of all children born in Korea between 2008 and 2009, and followed them until December 31, 2017. They identified 93,717 children in this cohort who during surgery received general anesthesia with endotracheal intubation (a tube inserted down the trachea), and matched them with an equal number of children who were not exposed to general anesthesia.

The team matched the unexposed group with the exposed group by age, sex, birth weight, residential area at birth, and economic status.

They then assessed both groups for subsequent diagnoses of ADHD.

In general, children exposed to general anesthesia were found to have a 40% greater risk of subsequently being diagnosed with ADHD than their unexposed peers.

This effect was found to be dose dependent by several measures:

  • Duration of surgery: two-to-three-hour surgeries were associated with a 50% greater risk of subsequent ADHD, and surgeries of more than three hours with a 60% greater risk.
  • Number of exposures: two exposures were associated with a 54% increased risk, and three or more exposures with a 67% greater risk.
  • Placement in an Intensive Care Unit was associated with a 60% greater risk of ADHD.

All three measures were highly significant.

The authors concluded, “exposure to general anesthesia with ETI [endotracheal intubation] in children is associated with an increased risk of ADHD … We must recognize the possible neurodevelopmental risk resulting from general anesthesia exposure, inform patients and parents regarding this risk, and emphasize the importance of close monitoring of mental health. However, the risk from anesthesia exposure is not superior to the importance of medical procedures. Specific research is needed for the development of safer anesthetic drugs and doses.”

Joo Young Song, Hye Ryeong Cha, Seung Won Lee, Eun Kyo Ha, Ju Hee Kim, and Man Yong Han, “Association Between Receipt of General Anesthesia During Childhood and Attention Deficit Hyperactive Disorder and Neurodevelopment,” Journal of Korean Medical Science (2023), 38(6):e42, https://doi.org/10.3346/jkms.2023.38.e42.

U.S. Food and Drug Administration, “FDA Drug Safety Podcast: FDA review results in new warnings about using general anesthetics and sedation drugs in young children and pregnant women,” January 14, 2022, https://www.fda.gov/drugs/fda-drug-safety-podcasts/fda-drug-safety-podcast-fda-review-results-new-warnings-about-using-general-anesthetics-and-sedation.

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A New ADHD Medication That Works Differently in the Brain

The FDA has approved a new once-daily pill called centanafadine (trade name SIMTRIYO®). Approved for adults and kids aged 6 and older (weighing at least 44 lbs / 20 kg), centanafadine is a new category of ADHD treatment that aims to give fast results with fewer of the downsides of traditional stimulants.

What Makes This Drug Different?

To understand why centanafadine is unique among medications for ADHD, it helps to look at how ADHD brain chemistry works:

  1. Norepinephrine: Powers focus, alertness, and attention span.
  1. Dopamine: Drives motivation, reward system, and decision-making.
  1. Serotonin: Regulates mood, anxiety levels, and emotional stability.

Stimulants like Ritalin and Adderall work mainly in the dopamine system.  Nonstimulants like atomoxetine, viloxazine, clonidine and guanfacine work mainly on the norepinephrine system.  Centanafadine is the first drug in a new class called NDSRIs (Norepinephrine, Dopamine, and Serotonin Reuptake Inhibitors). We can describe its effects as follows:

  • Heavy boost to Norepinephrine: Delivers the strong focus and attention boost you need.
  • Moderate, smooth increase to Dopamine: Helps with motivation and brain executive function without triggering massive dopamine spikes that lead to addiction or heavy crashes.
  • Moderate boost to Serotonin: Helps smooth out mood swings and keeps anxiety under control.

What Did Clinical Trials Show?

The FDA approved centanafadine based on studies involving thousands of adults, teens, and children. Here are the key findings:

Centanafadine showed some improvement in ADHD symptoms within the very first week of taking it although a full effect takes about six weeks.

In adult trials, taking 200 mg or 400 mg daily led to significant improvements in real-world skills:

  • Time management and prioritizing tasks
  • Starting projects without procrastinating
  • Planning complex tasks and staying organized
  • Short-term working memory

In trials with children (ages 6–12) and teens (ages 13–17), centanafadine significantly reduced core ADHD symptoms like hyperactivity, impulsivity, and lack of focus compared to a placebo.

About 30% to 40% of adults with ADHD also suffer from anxiety. Traditional stimulants can make anxiety worse. In a trial specifically designed for adults dealing with both ADHD and anxiety, centanafadine effectively treated ADHD symptoms without firing up their anxiety, which might be due to its serotonin boost.

Does Centanafadine have Side Effects?

While Centanafadine was well-tolerated by most people in studies, like any prescription medication, it comes with important safety guidelines.

Prescribing Warnings:

  • Suicidal Thoughts in Children: In trials for kids aged 6 to 12, centanafadine was linked to a higher risk of suicidal thoughts and behaviors compared to a sugar pill.  Although rare, parents and doctors should look for changes in mood or behavior, especially when starting or changing doses.
  • Stimulant Classification: Because it acts on central nervous system pathways, especially dopamine, centanafadine is classified as a CNS stimulant so might lead to addiction. While it has a much lower abuse risk than stimulants like Ritalin or Adderall, doctors should still evaluate patients for any history of substance abuse before prescribing.

Common Side Effects:

  • Kids & Teens: Decreased appetite, stomach ache, nausea, rash, and headache.
  • Adults: Dry mouth, difficulty sleeping (insomnia), decreased appetite, nausea, and headaches.

Other Warnings:

  • Heart & Blood Pressure: It can cause small increases in heart rate and blood pressure, so doctors will check these regularly.
  • Drug Interactions: It cannot be taken with certain antidepressants (MAOIs) due to dangerous blood pressure risks.

The Bottom Line

Overall, centanafadine is a new step forward in how we treat ADHD. Because it acts differently in the brain than traditional treatments, patients who struggle with stimulant-related anxiety or side effects may find it useful to explore with their doctor.

Nitrogen Dioxide Linked to Higher ADHD Risk: Insights from a Massive South Korean Study

A landmark nationwide study from South Korea has uncovered a significant link between prenatal exposure to air pollution — specifically nitrogen dioxide (NO2) — and an increased risk of ADHD in children. 

While researchers have long suspected that air pollutants interfere with fetal brain development through inflammation and oxidative stress, this study is one of the largest and most comprehensive of its kind, following nearly 1.5 million births for up to 13 years. 

Why South Korea? 

South Korea provided a unique countrywide “laboratory” for this research due to two key infrastructure strengths: 

  • Universal Health Data: A national insurance database that tracks the health outcomes of the entire population. 
  • Granular Air Monitoring: A network of 642 monitoring stations that allowed researchers to precisely estimate what pollutants mothers were breathing based on their postal codes. 

Key Findings: The “Smoking Gun” of NO2 

While the study looked at several pollutants, nitrogen dioxide — a byproduct of fossil fuel combustion in cars and power plants — emerged as the primary concern. 

Pollutant 

Association with ADHD Risk 

Nitrogen Dioxide (NO2) 

Strongest Link: Every 1-ppb (part-per-billion) increase in exposure linked to a 22% rise in risk. 

Sulfur Dioxide (SO2) 

Minimal Link: Only a slight 4% increase per ppb. 

Ozone (O3) carbon monoxide (CO), & particulates 

No significant association was found. 

The scale of the NO2 risk is particularly striking. Over the typical range of exposure levels found in the study (an interquartile range of 13 ppb), the data suggest a threefold increase in ADHD risk for children in the highest-exposure groups compared to the lowest. 

Accounting for Other Factors 

To ensure the results weren’t skewed by other variables, the researchers controlled for a wide range of confounders including: 

  • Socioeconomic and employment status. 
  • Maternal age and baseline health. 
  • The child’s sex. 
  • The presence of 14 different medical conditions around childbirth. 

The authors emphasized the strong association between maternal nitrogen dioxide exposure and ADHD, while also noting the small but significant association with sulfur dioxide.  

The Take-Away: A New Frontier for Public Health 

Historically, air quality laws have been designed to protect our lungs and hearts. However, this study adds to a growing body of evidence suggesting that the brain is likewise vulnerable. 

In a commentary on the findings, expert George Ayoub argued that “neurodevelopment should be explicitly considered” when governments perform cost-benefit analyses on air quality regulation.  My view is a bit different.  The association is intriguing but the study does not establish cause and effect.  Many statistically significant environmental risk associations for neurodevelopmental disorders have disappeared after controlling for maternal risk for ADHD.  I hope this research team will do those analyses if feasible.

New Meta-analysis Finds Structured Executive Function Training Largely Ineffective

Executive functions (EFs) are the cognitive control systems that allow people to pursue goals, make decisions, and adapt to changing circumstances. Researchers generally break them into three overlapping capacities: working memory (holding and manipulating information in mind), inhibitory control (suppressing impulses and filtering out distractions), and cognitive flexibility (switching between tasks or mental frameworks). Strong EFs in childhood predict academic achievement, social competence, and long-term mental health; weaknesses in these areas that go unaddressed can persist into adulthood, undermining school performance, career prospects, and well-being. 

The Background:

Interest in training these skills has grown rapidly, but most research has been conducted in Western settings. China presents a distinctive context. Collectivist values make group-based programs culturally natural, and parental investment in academic outcomes is high. Both of these factors should, in theory, work in an intervention’s favor. At the same time, tightly scheduled school days (sessions typically capped at 30 minutes or less) constrain what is actually deliverable. A growing number of randomized controlled trials (RCTs) have tested EF interventions with Chinese children, but until now, no one has pulled that evidence together systematically. 

The Study:

A new network meta-analysis did exactly that. The researchers screened RCTs involving Chinese children aged 3–12, including both typically developing children and those showing subclinical signs of ADHD or autism spectrum disorder (ASD), for instance, siblings of children with an ASD diagnosis. Children who already carried a formal neurodevelopmental diagnosis were excluded. Fifty-two trials covering nearly 3,000 children met the inclusion criteria. Interventions fell into four categories: 

  • Computerized adaptive n-back training with metacognitive coaching (strategy instruction and self-monitoring): 14 trials, 486 children 
  • Stop-signal and rule-switching tasks targeting inhibitory control and cognitive flexibility, delivered face-to-face: 18 trials, 632 children 
  • Hybrid physical-cognitive training moderate-to-vigorous aerobic exercise combined with concurrent cognitive demands (e.g., brisk walking while counting backward) in 20–30-minute sessions: 10 trials, 298 children 
  • Computerized cognitive flexibility training (set-shifting, dual-task coordination), self-paced with progressive difficulty: 10 trials, 312 children 

The headline finding is that three of the four intervention types produced statistically significant improvements across all three EF domains. The exception was the hybrid physical-cognitive program, which did not reach significance for inhibitory control. Positive results across the board might sound encouraging until you look at the actual effect sizes. 

The Results:

The actual effects were negligible. Every significant result fell well below what methodologists define as a “small” effect (a standardized mean difference, or SMD, of 0.2). The largest effect size in the entire analysis was an SMD of 0.097  (less than half that threshold). The authors summarize the interventions’ effects as “modest,” but that is generous phrasing for numbers that, in practical terms, amount to very little. The analysis also showed signs of publication bias, meaning that studies with null or negative results may not have been published, potentially inflating even these modest figures. 

The Take-Away: 

It is important to note that these results don’t necessarily mean that this is the last word on EF training. The results apply specifically to Chinese children working within the time constraints of Chinese school schedules, and they exclude children with diagnosed ADHD, a population for whom cognitive interventions sometimes show larger effects. Generalizing beyond those boundaries is unwarranted. 

What the findings do suggest is that structured EF programs, as currently implemented in Chinese educational settings, are not delivering meaningful real-world benefits. Statistical significance, it is worth remembering, is not the same as practical significance, and the gap between the two is sharp here. 

July 17, 2026