Donald Trump officially announced a link between prenatal exposure to acetaminophen and the risk of developing autism. This was met with both skepticism and victory by critics and proponents of an environmental link in the development of neurodevelopmental disabilities. The likelihood of the existence of a causal link between acetaminophen use and autism is unclear and the evidence is contradictory.

A review of 20 lines of evidence and a research study by Jonesill, John P., et al (2024) suggested that acetaminophen exposure leads to many, if not all cases of autism. This hypothesis is based on the understanding achieved through animal studies that acetaminophen changes brain metabolism and signaling and alters long-term behaviors in memory and social function (Jonesill, John P., et al., 2024). Some research even suggests that acetaminophen decreases empathy. The mechanism of injury is believed to be toxic metabolites of acetaminophen as it breaks down in the body, including N-acetyl-p-benzoquinone imine (NAPQI, believed to cause neural cell death (Jonesill, John P., et al., 2024).

The research in this area is conflicting though. Acetaminophen has antioxidant and anti-inflammatory properties. As such, it is thought to have a neuroprotective effect on hippocampal neurons and reduce oxidative stress, increasing cultured neuronal cell survival (Tripathy, Debjani & Grammas, Paula, 2009).

In 2021, Ahlqvist, Viktor H., et al., analyzed a cohort study of acetaminophen use during pregnancy with children who were at risk of autism, ADHD, and intellectual disability. What is remarkable about this study is that it surveyed 2, 480, 797 children born between 1995-2019 in Sweden. This study did something that past studies had not: It controlled for sibling diagnosis. The results indicated no association between prenatal acetaminophen exposure and a child’s risk of autism, ADHD, or intellectual disability (Allegaert, K & van den Anker, J., 2020). Why does this matter? Statistical models without sibling control where a link between acetaminophen use and autism has been found may be a victim of a confounding variable.

It is interesting to note that a causal relationship has been hypothesized to exist between acetaminophen and autism spectrum disorder due to a higher prevalence of autism in circumcised boys. Presumably, acetaminophen use during the procedure is considered to be the root cause (Jonesill, John P., et al., 2024). This is an example of how research studies can be interpreted in different ways. Frisch and Simonson (2015) hypothesized that exposure to a single painful stimulus can contribute to lifelong deficits in an individual’s stress response and that this is the reason for increased rates of autism in circumcised males.

There are many unanswered questions about the link between acetaminophen exposure and the development of neurodevelopmental disabilities. It is important to review studies carefully before suggesting and implementing new public policies in this area.

Allegaert, K., & van den Anker, J. (2020). How to translate neurocognitive and behavioural outcome data in animals exposed to paracetamol to the human perinatal setting?. Archives of medical science : AMS, 20(4), 1294–1306. https://doi-org.methodistlibrary.idm.oclc.org/10.5114/aoms.2020.100715

Frisch, M., & Simonsen, J. (2015). Ritual circumcision and risk of autism spectrum disorder in 0- to 9-year-old boys: national cohort study in Denmark. Journal of the Royal Society of Medicine, 108(7), 266–279. https://doi-org.methodistlibrary.idm.oclc.org/10.1177/0141076814565942

JonesIII, J. P., Williamson, L., Konsoula, Z., Anderson, R., Reissner, K. J., & Parker, W. (2024). Evaluating the Role of Susceptibility Inducing Cofactors and of Acetaminophen in the Etiology of Autism Spectrum Disorder. Life, 14(8), 918. https://doi.org/10.3390/life14080918

Mischkowski, D., Crocker, J., & Way, B. M. (2019). A Social Analgesic? Acetaminophen (Paracetamol) Reduces Positive Empathy. Frontiers in Psychology, 10, 538. https://doi-org.methodistlibrary.idm.oclc.org/10.3389/fpsyg.2019.00538

Tripathy, D. & Grammas, P. (2009) Acetaminophen inhibits neuronal inflammation and protects neurons from oxidative stress. J Neuroinflammation 6, 10. https://doi.org/10.1186/1742-2094-6-10