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Comment by gnode | Hacker News Reader

I think something which should be considered, is that gut bacterial abnormality is very plausibly a consequence of autism, rather than a cause. Selective eating and food refusal occurs in about three quarters of children with ASD, and has been used as a diagnostic criteria (which reinforces the correlation). Poor diversity in nutrition leads to poor biodiversity in the gut flora.

That said, poor gut biodiversity could in turn lead to exacerbated presentation of symptoms, due to gut flora's involvement in neurotransmitter systems, interactions with the gut's nervous system, or simply painful intestinal distress.

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The research cited in the article directly refutes what you are positing and shows that ASD symptoms are transferable via fecal transplant.

IN MICE.

Please don't use uppercase for emphasis.

https://news.ycombinator.com/newsguidelines.html.

Doesn't change anything but I think he's referring to this twitter account: https://www.twitter.com/justsaysinmice

I wonder if there should be a similar account for "in males".

I believe many medicines are tested in males only because it would be unethical to test them in possibly pregnant females. However, one ridiculous example is birth control pills.

Ah interesting. Thanks!

How did you know about that?

Been following it for a while, btw: https://mobile.twitter.com/michaelhoffman/status/11228390743...

This is not the first study ever to use mice for testing. I think it is very common.

Indeed, mice are often used as guinea pigs.

The problem with autism research on mice is that it is not at all clear that the mouse autism model has anything to do with autism in humans.

Possibly, but consider this from the article:

> Crucially, these changes in gut bacteria have translated into behavioural changes. Even 18 weeks after treatment started the children had begun showing reduced symptoms of autism. After two years, only three of them still rated as severe, while eight fell below the diagnostic cut-off point for asd altogether. These eight thus now count as neurotypical.

Wow. That is incredible.

If it works both directions - almost makes me wonder if there are bacteria that can manipulate our brains (causing picky eating) to get their preferred food and keep themselves in the majority in the gut.

Regulatory capture for bacteria.

I mean, look at what Toxoplasma gondii does to mice...

There is quite a bit of evidence to suggest that actually [0].

[0] https://onlinelibrary.wiley.com/doi/full/10.1002/bies.201400...

Knowing what we now know, it would be surprising if that weren't the case. What's the likelihood of no bacteria figuring out that trick?

Given the selection pressures involved, we might even expect most gut bacteria to do that.

So changing dietary habits is not just about challenging your reward system, but also starving out the invasor?

Imagine a world where you can buy your food tastes through a yogurt.

Fortunately, they're not influencing gut flora research to make humans treat some species preferentially. This would be way too complex for simple creatures that don't have their own nervous system.

Another straightforward possible mechanism is that upset stomach exacerbates behavioural systems.

Consider anything you do that takes conscious effort, in life or work. Now try doing it with a headache, or on lack of sleep, or with a stomach pain. You'll do worse!

I mean, yes, but to go from severe ASD behaviors to neurotypical is vastly different than perhaps some behavioral artifacts from a headache or stomach pain. I think your conclusion is greatly understating the result.

I wonder whether much of the difference in severity of autism symptoms, rather than being differences in the underlying condition are explained by differences in comfort. Symptoms used to differentiate sever cases such as irritability, inattention, repetitive behaviour, mood changes, sleep disruption, and hyporeactivity are all exhibited by neurotypical people when in pain / discomfort / stress.

A core feature of autism is sensory abnormality, so perhaps the symptoms present in severe cases can be explained by increased sensitivity to these negative internal stimuli.

Additionally, I think it's important to note that we would discount many of these symptoms from a diagnosis, if a more observable and salient cause (e.g. an itchy skin condition) were seen. Gastrointestinal discomfort being poorly observable creates a bias.

How likely were they to regress to the mean if we did nothing at all?

We can't know without a control

> Selective eating and food refusal occurs in about three quarters of children with ASD

I’m sure there are differences between ASD and non-ASD kids in terms of diet, but picky and selective eating is present in a lot of children that are never diagnosed as ASD.

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