Autism: debunking Trump claims, and what scientists still don't know

Summary of Autism: debunking Trump claims, and what scientists still don't know

by NPR

13m•February 3, 2026
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Overview of Shortwave — "Autism: debunking Trump claims, and what scientists still don't know"

This NPR Shortwave episode (host Emily Kwong, with brain correspondent John Hamilton) examines recent government statements about autism, corrects widespread misinformation, and summarizes what science reliably says — and still does not know — about autism spectrum disorder (ASD). The episode covers disputed claims about vaccines, Tylenol, and vitamin B9 (leucovorin); the history of harmful autism theories; contemporary estimates and drivers of rising diagnoses; and new biological research (including brain organoids) probing autism’s diversity.

Key takeaways

  • Claims that groups who avoid vaccines "have no autism" are false. Autism has been observed across populations worldwide regardless of vaccination status.
  • Current evidence does not support a causal link between maternal acetaminophen (Tylenol) use and autism: large, rigorous reviews find no association; some small studies and meta-analyses suggested possible links but had important confounders (e.g., infection, fever).
  • Proposals to broadly treat autistic children with leucovorin (a form of vitamin B9) are premature. It’s unclear how many autistic children have B9 deficiency or whether leucovorin improves core symptoms; pediatricians and neurologists oppose wide distribution.
  • Vaccines are not a risk factor for autism. Historical concerns about mercury (thimerosal) are largely obsolete; thimerosal has been removed from most vaccines for decades.
  • The apparent "rise" in autism prevalence is largely due to increased awareness, broader diagnostic criteria (DSM-5 consolidated autism-related diagnoses in 2013), more screening, reduced stigma, and better recognition in girls — not necessarily a true biological epidemic.
  • Autism is biologically complex: strong genetic components (including inherited and spontaneous mutations), some environmental risks (e.g., prenatal heavy metal exposure), and varied brain-development patterns. But no single biomarker currently identifies autism in an individual brain scan.

Topics discussed

  • Recent government claims about autism (remarks from 2025 press conference)
  • Tylenol (acetaminophen) and autism risk: studies from 2024–2025 and methodological issues
  • Leucovorin (vitamin B9) as a proposed treatment and professional skepticism
  • Vaccine safety and the persistence of vaccine-related misinformation
  • Historical myths: "refrigerator mother" theory and early incorrect hypotheses
  • Prevalence trends and reasons for increased diagnoses (CDC ~3.2% of 8-year-olds)
  • Biological research into autism: genetics, spontaneous mutations, brain development, and organoid studies
  • The potential to subtype autism biologically to guide targeted treatments

Evidence & science explained

  • Prevalence: CDC data cited — ~3.2% of eight-year-olds are diagnosed with ASD (about double the 2010 rate). Much of this increase is attributed to diagnostic, social, and awareness changes.
  • Genetics:
    • Twin studies show high heritability (identical twins 60–90% concordance in some studies), indicating a strong genetic component.
    • Hundreds of genes implicated; complexity suggests many biological pathways can lead to autism.
    • Spontaneous (de novo) mutations — especially those occurring in sperm from older fathers — account for a large fraction of cases in low‑risk families.
  • Environmental risks:
    • Prenatal exposure to certain heavy metals (lead, mercury) can increase risk due to effects on early brain development; exposures have declined over decades.
    • Large, well-controlled studies do not support vaccines or routine Tylenol use in pregnancy as causal for autism.
  • Brain differences:
    • Group-level patterns: atypical early growth (accelerated in first years then slowed) and altered connectivity — often stronger local connections but weaker long-range connections.
    • No current scan/biomarker can definitively diagnose autism in an individual.
  • Organoid research:
    • Lab-grown human brain organoids (modeling fetal brain development) allow functional tests of autism-associated genes.
    • Work by Dr. Sergiu Pasca (Stanford) and colleagues shows ~10% of tested genetic changes prevented interneuron generation or migration in organoids — suggesting specific developmental processes can be disrupted by certain mutations.
    • Goal: identify biological subtypes of autism, which could enable targeted therapies for particular disrupted systems.

Misconceptions and statements debunked

  • "Groups that don't take vaccines have no autism" — incorrect. Autism has been found across demographic and cultural groups worldwide; vaccination status does not determine autism prevalence.
  • Tylenol causes autism — not supported by best available evidence. Some smaller studies suggested possible associations but failed to control for key confounders (fever/infection); larger and more rigorous reviews found no link.
  • Government plan to formalize leucovorin for autistic children — premature and not supported by conclusive evidence that B9 deficiency is common in autism or that leucovorin improves core ASD symptoms.
  • Claims of a toxin-driven "epidemic" (e.g., RFK Jr.) — misleading. Certain toxins (lead/mercury) can raise risk, but exposures have decreased; the lists of alleged culprits often include factors (like vaccines) that lack supporting evidence.

What scientists still don't know (open questions)

  • How many biologically distinct forms (subtypes) of autism exist, and can they be reliably identified?
  • Which specific biological pathways are responsible for the diversity of autism presentations?
  • How exactly do genetic variants (and combinations of variants) translate into altered brain wiring and behavior?
  • What is the full contribution of prenatal and early-life environmental exposures, especially subtle or interacting exposures?
  • Can targeted, mechanism-specific therapies be developed for particular biological subtypes of autism?

Notable quotes / historical context

  • From the 2025 press conference (paraphrase): "There are certain groups of people that don't take vaccines and don't take any pills that have no autism." — example used to illustrate misinformation.
  • Historical misstep: Bruno Bettelheim and the "refrigerator mother" theory blamed parental warmth for causing autism — a discredited and harmful hypothesis that persisted into the 1970s.
  • Organoid insight (Dr. Sergiu Pasca): some autism-associated gene changes can prevent interneurons from being born or migrating properly — pointing to specific developmental disruptions.

Practical recommendations (for listeners)

  • Vaccinations: continue to follow public-health guidelines — vaccines are safe with respect to autism risk.
  • Pregnancy and medication: current evidence does not support avoiding acetaminophen solely due to autism concerns; pregnant people should consult their providers about fever, pain management, and risks.
  • Treatments: be cautious about widely adopting unproven treatments (e.g., leucovorin) for autism without guidance from pediatricians/neurologists.
  • If concerned about development: seek screening and evaluation early — diagnoses can open access to therapies and supports.
  • Stay critical of sensational claims; look for large, well-controlled studies and expert consensus.

Further listening / resources mentioned

  • Shortwave episodes on Tylenol and autism
  • Shortwave reporting on Fragile X Syndrome (reported by John Hamilton)

If you want a one-line summary: the episode debunks several high-profile false claims about autism (vaccines, Tylenol, blanket vitamin B9 treatment), explains why diagnoses have increased, and highlights promising but early biological research aimed at parsing autism into distinct, targetable subtypes.