If these neurocognitive effects were actually measurable, they wouldn't need to cherry-picking population-level correlation studies to find effects that are within the margin of error of the tests.
When I took my daughter to see a dentist here, the dentist saw my daughter's good teeth during the check-up and said, "You didn't grow up here, did you?"
Most European countries including Italy, France, Finland, Germany, Sweden, Netherlands, Scotland, Austria, Poland, Hungary and Switzerland do not fluoridate water.
https://en.m.wikipedia.org/wiki/Water_fluoridation_by_countr...
Make your own conclusions.
Heavy industry, the dental industry, and your municipalities are lying to you when they say that drinking fluoride helps your teeth.
Now when a dentist applies a fluoride treatment in a paste or appliqué, the solution stays in contact with living bone for a significant dosage time. The process is known as "remineralization" and so there is scientific basis for such a treatment to be effective.
But when you drink water with the same substance, it quickly washes around those bones and into your esophagus. It doesn't stick around. It's like getting a cross tattoo to become Jesus. Fluoride will be digested, and absorbed into your bloodstream, and cross your blood-brain barrier, for sure! But it won't stay adhering to your tooth-bones and the remineralization process never has a chance to start. That's absurd thinking that it somehow is internally effective. It's simply not the mechanism of action. There's not enough time for it to work. The process requires physical contact in order for a chemical reaction to occur!
Fluoride is, however, well-known to produce favorable psychoactive effects. For the past century or more. That's why we got Prozac, where the active ingredient is "fluoxetine". Prozac was the next step forward in getting fluoride to the masses who may not drink black/green tea, or live in fluoridated municipalities.
I have a meta-hypothesis that excess surplus of any product is often remarketed as beneficial. For example, heavy industry produced massive amounts of talc and they were able to parlay it into many products as a powder. I simply feel the same way about minerals such as magnesium. How much Epsom salt is sold, simply because industries need to unload this stuff by the 5lb bag, vs. how good it works in a bathtub, I don't really know. But I literally envision cigar-filled back rooms where executives go "we can profit by digging a lot of this crap out of the ground and putting it on store shelves, or just dumping it right into water supplies, if only there's a way to convince everyone it's good for them!" And there's nothing different with the way lithium's being used, either. It used to be a soft-drink additive! Wait until they begin lithiating all your potable water supplies! (Sort of horrific, because side effects of lithium consumption include polydipsia and polyuria...!)
But fluoride is the biggest scam of the 20th century. It's pseudoscience and quackery that sold it to the general public, and your cities are literally lying through their teeth when they don't tell you their ulterior motive and they pretend that there is "evidence" of beneficial effects on teeth. Nothing could be further from the truth. Y'all might as well believe in phrenology and astrology.
As for efficacy, the same (or greater) benefits to enamel hardness can be obtained from using fluoride toothpaste anyway, I do not see the urgency for this. They've stopped fluoridating their water in Scandinavia for years now.