With my day job (partly immunology) hat on, I think that it looks very promising.

The researcher's idea of using a "probiotic" (a bacterial strain) is a good one - it is part of what is a hot topic with biomedical scientists - there is increasing evidence that differences in the kinds of bacteria that normally live in the gut - the "gut microbiome" are important in both physical and mental health issues.

I hope that it gets confirmed by larger studies - 62 subjects in the study is not a big number.