Decades of cognitive neuroimaging research into the autistic brain highlight the immense complexity of understanding autism spectrum disorder (ASD). As Professor Gina Rippon, a professor emeritus of cognitive neuroimaging, explains, the quest to understand 'How do autistic brains get to be autistic?' is akin to searching for needles in a field of haystacks, given the 86 billion neurons and 100 trillion connections in a typical human brain. Autism is a neurodevelopmental condition present from conception, not a disease, and manifests in an enormously wide array of behavioural symptoms. This leads to the field's adage: 'if you've met one person with autism, you've met one person with autism,' signifying it is not a single condition with a single cause.

This nuanced understanding stands in stark contrast to recent claims made by President Donald Trump, who, following a review commissioned by US Health Secretary Robert F Kennedy Jr, declared a link between mothers taking paracetamol during pregnancy and autism. This announcement, suggesting a 'problem solved' and an 'answer to autism,' was met with widespread outrage and skepticism from the global medical community. Professor Rippon cautioned against the 'dangerous and simplistic' act of drawing firm lines between such a complex condition and one cause, drawing parallels to the discredited 1998 claims by Andrew Wakefield linking the MMR vaccine to autism, which caused lasting damage to vaccine uptake.

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Paracetamol, widely sold as Panadol in the UK and Tylenol in the US, is a common painkiller for expectant mothers, recommended by the NHS as the 'first choice' for short periods at the lowest effective dose. Approximately half of pregnant women in the UK and 65 percent in the US use it. While some studies have suggested a possible link between maternal paracetamol use and higher rates of autism or ADHD, such as reviews by Harvard scientists and a recent analysis by Mount Sinai and Harvard researchers, the evidence remains inconsistent and far from conclusive.

These studies often advise pregnant women to consult doctors and use paracetamol sparingly, emphasizing that the findings do not prove direct causation. Conversely, other significant studies, like a 2024 analysis of 2.4 million Swedish children by the Karolinska Institute, found no association whatsoever between paracetamol use during pregnancy and a child's risk of autism. Britain's Medicines and Healthcare Products Regulatory Agency(MHRA) explicitly stated there is 'no evidence that taking paracetamol during pregnancy causes autism in children.'

The emphasis on a single environmental cause, as suggested by RFK Jr. who stated, 'This is a preventable disease... We know it's an environmental exposure. It has to be,' largely ignores crucial aspects of autism. Experts highlight that autism is highly heritable, with over 800 genes identified as associated with the condition, making it one of the most heritable mental health conditions. Early clinical observations from the 1940s, including those by Leo Kanner, noted unusual behaviours in parents and relatives of autistic children, pointing towards a genetic component that cannot be dismissed by a simple link to paracetamol use.

The perceived 'boom' in autism rates since the early 20th century, from 0.05 percent to one in 36 children in the US and one in 57 in the UK, is largely attributed to widened diagnostic criteria, increased awareness, detection, and acceptance, rather than a genuine epidemic from a novel cause. Past 'scaremongering rhetoric' linking autism to unspecified 'environmental toxins' or mercury in vaccines and dental fillings have been thoroughly investigated and rejected. While some studies have linked low maternal folate levels during early pregnancy to an increased autism risk, suggesting a protective effect from folic acid supplements, these findings are not entirely consistent across all large studies.

Furthermore, the Trump administration's alleged plan to claim leucovorin, a folic acid derivative used in chemotherapy, as a possible autism treatment, exemplifies a concerning trend of promoting simplistic 'pill-for-a-pill' solutions. The reality is that advances in understanding autism stem from persistent research, stunning genetic research techniques, exponential leaps in computing power, human genome sequencing, and large-scale collaborative scientific efforts.

Beyond the autism debate, leading doctors warn that paracetamol, despite its common use and over-the-counter availability, carries significant risks when taken regularly, even at 'safe' doses. While occasional use for headaches or short-term pain is generally considered safe, prolonged or excessive use can severely damage the liver. Pharmacists, like Thorrun Govind, stress that paracetamol is not harmless, and Dr Leyla Hannbeck of the Independent Pharmacies Association warns that exceeding recommended doses, even by a few tablets over days or weeks, can be 'very harmful and even fatal,' leading to liver, brain, and kidney damage. Professor Andrew Moore highlights studies associating paracetamol with increased rates of death, heart attack, stomach bleeding, and kidney failure, noting it can cause liver failure even at standard doses, albeit rarely.

Concerns over overdose led the UK Government to restrict paracetamol sales in 1998. The danger persists through 'staggered overdosing,' where patients subtly exceed daily limits over time, and accidental overdosing due to paracetamol being a hidden ingredient in many cold, flu, and combination remedies. Paracetamol is now the leading cause of acute liver failure in UK adults, with doses of around 7.5g in 24 hours potentially triggering toxicity in some. This occurs because the liver's natural detoxifying agent, glutathione, becomes depleted when processing the drug's toxic by-product, NAPQI, at high or prolonged doses.

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Adding to these concerns, the National Institute for Health and Care Excellence (NICE) revised its guidelines in 2020 to advise against using paracetamol for chronic pain, citing a lack of evidence for its efficacy and potential harms like liver toxicity, kidney damage, and gastrointestinal problems. Health Secretary Wes Streeting urged the public to 'not pay any attention whatsoever to what Donald Trump says about medicine,' advocating for reliance on British doctors, scientists, and the NHS.

Ultimately, while paracetamol remains the recommended first-choice painkiller for pregnant women for short, low-dose periods, as untreated pain or fever also poses risks, the medical community strongly dismisses the simplistic claims linking it definitively to autism, while concurrently urging caution regarding its general long-term or excessive use due to other well-established health risks.