What do you think is the future of this treatment?

 

Example - autism symptoms reduced 47% 2 years after Fecal Microbiota Transfer:

https://www.sciencedaily.com/releases/2019/04/190409093725.htm

 

 

"Scientists discovered a human trait that wasn't linked to the microbiome, but they've forgotten what it is" - twitter anon. 

Research on the gut-brain axis is pretty nascent, but I would expect to see a lot more of the foundational research in the field to start manifesting in clinical applications in the foreseeable future.  

One thing I would like to add is that while associations have been found, many studies cannot really tease out the effect size. In other words, even if they have an impact, we do not know exactly how much. I think the area has a huge uncertainty when it comes to eventual clinical impact. Part of it is also because immune homeostasis and associated mechanisms are maddingly complex.

Reduction of core symptoms of autism by 47% is a huuge thing. This is a condition that previously had no effective treatment options. 

The issue is that it is not clear whether the effects are solely due to the implants (especially as only 18 children were tested) . Moreover, the indicated number is based on averages. On the more individual level on can find a rather huge range of shifts with some basically being at the same level and others experiencing massive reduction (which resulted in the reported average). We have no idea what the trajectory of the children would be without a treatment. Also, it is important to note that all children had gastrointestinal problems, which is why they were treated in the first place. As Arete pointed out, it could be that there is a connection with these issues along the gut brain axis i.e. GI issue might exacerbate autism symptoms. And treating those might lessen said symptoms. However, that would mean that folks with autism but no GI issues might not benefit from such a treatment.

The study at best invites a double-blinded study at which point we could evaluate the effects over a placebo treatment. It could be somewhat tricky to design a good study, though. 

Does it  warrant a larger trial in your opinion? 100-150 participants?

It requires a specific design to tease out effects. The study was observational- kids were treated for a GI disorders and the researchers looked at how the treatment affected their autism scores. A different type of study is required to identify treatment efficacy. However that is non-trivial. AB treatment without indication can be harmful, especially to children, so I have a hard time finding a way to replicate the study in healthy children (but with autism symptoms), for example.

But for typical treatments one would at least have a control group (usually placebo treated) and then see how much the difference the treatment group experiences over the control. But that requires a well-designed and ideally diverse cohort. How many people are needed depend ultimately on the effect size but also the expected variation (in terms of outcomes)  in the cohort.