The study, published in PNAS, examined Wisconsin state testing records, archival information about when Wisconsin cities began to fluoridate their water, and data from the Wisconsin Longitudinal Study, which has followed a random sample of 10,317 high school seniors from 1957 through 2026. Key findings include:
- There is no evidence supporting a connection between community water fluoridation and children’s IQ.
- There is also no evidence supporting a connection between community water fluoridation and cognitive functioning at various points later in life.
- Findings confirm evidence published in previous research which also used a national sample, but considered school achievement test scores instead of actual IQ scores.
Decreasing number of cavities in children != increasing IQ
IQ only measures the ability to solve problems and pattern-match. And I would assume IQ tests are taken after cavities are dealt with.
To give an example, it’s the same thing as if you tried to give an IQ test to someone who, in the past, has had a bacterial infection. Then, when the person is perfectly healthy, you give them an IQ test once, then some antibiotics, then another IQ test giving the same result as the first. You would not conclude that antibiotics are ineffective and should be banned!