It's pretty much a proven fact that gut microbiota is related to neurological diseases: [Link Between Alzheimer’s and Gut Is Confirmed](https://www.theepochtimes.com/link-between-alzheimers-and-gut-is-confirmed_4208435.html) >>Butyrate — an SCFA produced when gut bacteria ferment fiber — activates the secretion of brain-derived neurotrophic factor (BDNF), reduced levels of which have been linked to Alzheimer’s disease. >>“Our results are indisputable: Certain bacterial products of the intestinal microbiota are correlated with the quantity of amyloid plaques in the brain,” explains Moira Marizzoni, a study author with the Fatebenefratelli Center in Brescia, Italy. [Fecal Microbiota Transplantation from Old Mice to Young Mice Impairs Cognitive Function](https://www.fightaging.org/archives/2020/10/fecal-microbiota-transplantation-from-old-mice-to-young-mice-impairs-cognitive-function/)