> 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.
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...
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.
> 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.