Autism Has No Single Cause. Here’s How We Know | Hacker News Reader

Autism Has No Single Cause. Here’s How We Know

scientificamerican.com

46 pointshbcondo71417 comments

Some forms of autism are highly inheritable. Asperger's Syndrome is inheritable at a rate of about 80%. In these cases the cause is genetic, but genetics is likely only one of many potential causes. '

But even "genetics" isn't really a single cause because it's over 200 different genes that each have an effect.

"A large new study published in the International Journal of Hygiene and Environmental Health provides evidence that exposure to certain workplace chemicals among parents may influence the severity of autism spectrum disorder (ASD) symptoms and contribute to behavioral, cognitive, and adaptive challenges in their children. The findings suggest that occupational exposures—especially to plastics, ethylene oxide, phenols, and pharmaceutical agents—may have broader developmental effects beyond autism diagnosis alone."

"The effects of parental occupational exposures on autism spectrum disorder severity and skills in cognitive and adaptive domains in children with autism spectrum disorder" https://www.sciencedirect.com/science/article/pii/S143846392...

The person leading this study, Erin C. McCanlies, was forced out of the CDC, her division eliminated and she went into early retirement from the CDC. https://www.psypost.org/scientist-who-linked-autism-to-chemi...

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"The findings suggest that workplace exposures to several specific chemical classes were associated with worse outcomes in children with ASD. One of the strongest and most consistent patterns involved plastics and polymer chemicals. Fathers’ exposure to plastics was associated with lower scores across all cognitive and adaptive skill domains, including language, motor coordination, daily living skills, and overall functioning. When both parents were exposed, the deficits appeared to compound.

“I was surprised how strongly and consistently plastics and polymers stood out as being linked with multiple developmental and behavioral outcomes including irritability, hyperactivity, and daily living,” McCanlies told PsyPost.

Exposure to ethylene oxide—commonly used in hospital sterilization—was also linked to more severe autism symptoms, lower expressive language abilities, and poorer adaptive functioning. Similarly, parental exposure to phenol (used in construction, automotive, and some consumer products) and pharmaceuticals was associated with increased ASD severity and more pronounced behavioral challenges, especially hyperactivity and stereotyped behavior.

While the results do not imply that all children exposed to these chemicals will develop more severe symptoms, the patterns suggest that early life exposure to workplace toxicants may amplify certain developmental difficulties in children who already meet criteria for ASD. The study provides one of the most detailed looks to date at how parental occupation may relate not just to diagnosis, but to variation in how autism is expressed.

“Our findings suggest that certain parental workplace exposures may be related not just to autism, but to worse symptoms and autism behaviors,” McCanlies explained."

> The $1-trillion cuts to Medicaid

No, that is false. The state Democratic parties are going to cut far, far more.

> the Trump administration

You just knew that was coming. My previous statement is unmentioned of course, despite the obviousness of it. That's how propaganda works. Roughly 6-7% of this article.

> The OBBBA language that cut and restructured Medicaid included explicit exemptions for people classified as "medically frail", which in federal Medicaid law covers people with physical, intellectual, and developmental disabilities.

Just kidding, we know full well that's not in this article.

> biology ... genes

For a article on a medical topic, this article says almost nothing about the underlying biology of autism, at least nothing more than an American Eagle ad. It is really all about that closing, to keep the fire going.

Propaganda. Sorry I couldn't get to this article sooner, I was editing Wikipedia on healthcare topics, pretty much fighting against everything this article is about.

I'm going to spend about 5 minutes and maybe do a better job at science than this article:

Autisms are biologically caused by disruptions in early brain development that alter how synapses are formed, pruned, and regulated, producing imbalances in excitatory and inhibitory signaling across neural circuits. Most cases trace to combinations of genetic variants—some rare, high-impact mutations affecting synaptic scaffolding (e.g., postsynaptic density proteins), neuronal excitability (ion channels), chromatin remodeling, or transcriptional control, and many common variants with smaller effects—while prenatal factors such as maternal immune activation, teratogens, or perinatal stress can act as modifiers. These converging influences disturb synaptic wiring, circuit dynamics, developmental timing, and gene-expression programs, leading to atypical brain connectivity: often locally hyperconnected yet underintegrated across distant regions. This altered network balance underlies the sensory, communicative, and behavioral traits recognized as the autism spectrum.

Synapse Formation and Balance:

– Faulty assembly and regulation of excitatory and inhibitory synapses.

– Leads to unstable network tuning, “noisy” signaling, and altered local vs. global connectivity.

Neuronal Firing and Circuit Dynamics:

– Changes in ion channel function distort how neurons spike and synchronize.

– Affects rhythmic activity (oscillations) important for sensory integration and social cognition.

Neurodevelopmental Timing:

– Mistimed growth, migration, and pruning of neurons.

– Results in atypical wiring patterns: often hyperconnected locally but underconnected long-range.

Gene Expression Control:

– Master regulators fail to coordinate large developmental programs.

– Produces ripple effects across hundreds of downstream pathways, compounding small errors.

Same story with ADHD: the symptoms can be caused by many things.

I‘m a bit disappointed that the article doesn‘t mention the link between low dopamine and autism. Here is just a recent study:

https://news.ki.se/new-study-links-dopamine-to-autism-sympto...

From the study:

„ This suggests that increased Ca2+ levels can compensate for deficits in β2-nAChR function and restores DA release.“

Calcium plays an important role here: https://www.stridesaba.com/calciums-role-in-supporting-indiv...

It occurs to me that pain killers can cross the placenta and also affect gut microbes, and that since sometimes autism isn’t inherited, there’s a gut microbe imbalance component to autism that needs more attention, especially related to how gut microbes differ in those born with and without Caesarians. Secondly, how are genes related to autism also linked to the gut-brain axis.

Gut health isn’t mentioned in the article, so it seems like a good point to bring up.

You’re not saying Tylenol causes autism, are you?

I am saying it’s possible there’s a gut-brain axis being affected by any number of factors. Consider Caesarian babies. I didn’t look it up, but I think since Caesarian babies aren’t exposed to bacteria from the vaginal canal, it perhaps contributes to their condition.

It's technically possible that early-life microbiome differences from bypassing the birth canal could influence it, but the fact that the association disappears when siblings who were delivered differently are compared is suggestive.

"However, the association did not persist when using sibling controls, implying that this association is due to familial confounding by genetic and/or environmental factors." - https://jamanetwork.com/journals/jamapsychiatry/fullarticle/...

That’s interesting but it’s hard to conclude anything without measuring titers during births which do and don’t result in ASD.

From TFA: (archive link: https://archive.ph/5CeZe)

> Other factors that have been linked to autism include people being born prematurely or through cesarean section, as well as pregnant people having obesity, using certain medications (such as the antiseizure drug valproate) and the pain reliever acetaminophen (the active ingredient in Tylenol) and being exposed to air pollution. The strength of the evidence for these links varies, though, and the increases in risk tend to be small. The evidence is also only correlational, meaning it can’t establish what caused what.

> Acetaminophen is also usually used as a fever reducer, which pregnant people might take if they are fighting an infection. Both infections and uncontrolled fevers during pregnancy have been linked to higher rates of autism. “We know that the neurodevelopmental outcomes of having an uncontrolled fever are worse than what we’re observing for acetaminophen,” Mandell says.

How’s it not fucking clear that the gut-brain axis of fetuses isn’t mentioned in the article.

Not only that, but the effects measured in the present studies have never even considered varying titers in vaginal canals during births, at least as far as I know.

Science isn’t gospel, don’t treat it like so. The original comment is a hypothesis, but it's based on existing evidence.

Here's some information from another comment,

https://news.ycombinator.com/item?id=45215745

> also affect gut microbes

Which painkillers? Do you have a citation for that? Note that ibuprofen is generally prohibited in pregnancy.

I believe acetaminophen is prescribed routinely during pregnancy because it’s considered safe to use, but it’s indicated that there may be a link between its use and outcomes, https://pmc.ncbi.nlm.nih.gov/articles/PMC9385573/

Here’s some additional information from another paper

> The gut microbiome has been implicated in the pathophysiological mechanisms of ADHD through the MGBA. Alterations in the MGBA contribute to neuroinflammation and oxidative stress, leading to ADHD core symptoms and associated comorbidities such as sleep disturbances. There is some evidence indicating maternal stress and the use of acetaminophen, which is a common pain reliever and fever reducer, may increase the risk of ADHD in offspring during pregnancy

https://www.mdpi.com/2075-1729/14/10/1234

It’s “settled science.” No need to investigate further. There’s nothing behind the curtain.

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