Aetiology of autism: findings and questions.
Genes remain the strongest autism cause; MMR vaccine and mom’s smoking are cleared, while prenatal infection and gut bugs are new angles to watch.
01Research in Context
What this study did
The author read every paper on what causes autism. He looked at genes, vaccines, and other risks. He wrote a story-style review in 2005.
No new lab work was done. He simply summed up the best evidence at the time.
What they found
Genes came out on top. Many studies pointed to hidden gene changes, but no single gene was named.
The MMR vaccine showed no link. Study after study found zero connection to autism.
Other ideas—like mom’s smoking or vitamins—had weak or no support.
How this fits with other research
Szatmari et al. (2004) set the stage. They warned that gene studies must match families carefully. Roll (2005) used that advice to judge the gene data.
Tioleco et al. (2021) added a twist. Their big meta-analysis found prenatal infection raises risk a little. This extends Roll (2005) by adding an environmental factor that holds up.
Biagioli et al. (2025) go further. They say gut bugs may shape autism traits. This 2025 view builds on Roll (2005) by adding a brand-new body system to watch.
Freeman et al. (2015) and Virk et al. (2016) close doors. Smoking and folic acid pills do not raise or lower risk. These null results back Roll (2005) call to quit chasing weak leads.
Why it matters
You can stop repeating the MMR myth to worried parents. Point them to genes and, maybe, prenatal health. Track new gut-brain findings, but don’t overhaul diets yet. Keep your focus on skill building, knowing biology is mostly set.
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02At a glance
03Original abstract
BACKGROUND: Although there is good evidence that autism is a multifactorial disorder, an adequate understanding of the genetic and non-genetic causes has yet to be achieved. METHODS: Empirical research findings and conceptual reviews are reviewed with respect to evidence on possible causal influences. RESULTS: Much the strongest evidence concerns the importance of susceptibility genes, but such genes have yet to be identified. Specific somatic conditions (such as tuberous sclerosis and the fragile X anomaly) account for a small proportion of cases. Over recent decades there has been a major rise in the rate of diagnosed autism. The main explanation for this rise is to be found in better ascertainment and a broadening of the diagnostic concept. Nevertheless, some degree of true rise cannot be firmly excluded. However, the epidemiological evidence on the main hypothesized environmental explanation, namely the measles-mumps-rubella vaccine, is consistently negative. CONCLUSION: Progress on the elucidation of the causes of autism will be crucially dependent on the combination of epidemiology with more basic science laboratory studies.
Journal of intellectual disability research : JIDR, 2005 · doi:10.1111/j.1365-2788.2005.00676.x