Mercury and aluminum injected into children repeatedly ain't too grand, but there's also an immunogenic brain damage component. Look up microglial priming by Blaylock in particular. There are a number of mechanisms.

Neuroimmunology
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3589867/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3784951/

Immunoexcitotoxicity
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909100/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3307240/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609793/

Hepatitis B vaccine induced brain dysfunction.
https://www.ncbi.nlm.nih.gov/pubmed/27501128
https://www.ncbi.nlm.nih.gov/pubmed/29751176

You have the well reported alteration of antigen presentation in the gut, massive inflammation. That's against a background of other environmental factors which destroy proper gut flora.
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