In Cuba, Vaccinations are not optional. There is a very low to almost not incidence of Autism or Alzheimer's/dementia. (Consider that all foods in Cuba are grown organically and have been for about 50 years). Another interesting fact is that Acetaminophen is not available over the counter and a prescription is required for this drug. Parents are not urged to give their children Acetaminophen after vaccinations are given as they are here in the US. Acetaminophen is not an acceptable drug to be given to children/babies. After learning about Acetaminophen restrictions in Cuba, I found at least one research paper written by an American doctor who feels Autism is connected to this drug. Not sure there was any follow-up, but would not be surprised since the maker of Tylenol (name brand most recommended by pediatricians) has very, very deep pockets.
Pediatricians do not currently recommend acetaminophen or any antipyretics around immunizations. This change is due to a few studies in the past decade that have suggested antipyretics can interfere in the immune response. The point you raised above about the potential neurotoxicity from acetaminophen is also there. The evidence is still evolving on this but it wouldn't surprise me if there was something there with chronic use at high doses.