#164 - RFK Jnr was right - but The Devil's in the Details
In 1999, I sat in class as a student and learned how to assess children’s IQ.
From 2006, I stood at the front of the class as a lecturer and taught 100s of students how to measure a child’s IQ.
This week, RFK Jnr was asked to respond to accusations of him being a conspiracy theorist.
RFK Jnr cited a few examples of how he had said things in the past, and now they have come to fruition.
One of those examples was that a recent meta-review supported his previous notion that flouride in water led to lower IQ in children.
I looked up this study - and the results did support was RFK Jnr had said in the past.
To Some Extent …
Meta-analyses collate quality data from quality studies to help us answer a research question - to quote RFK Jnr, that “fluoride lowered [a child’s] IQ”.
The meta-analysis that RFK Jnr mentions in his defense was publised last month in JAMA Pediatric.
Here’s the characteristics of that study that support RFK Jnr’s predictions:
there was a significant link between fluoride levels in children’s IQ scores.
there was remarkable consistently in this finding across studies - meaning oftentimes you’ll see some studies that do support a finding, some on the line, and others that don’t.
the meta-analysis analysed data from 74 studies, 64 of which were cross-sectional - 10 were prospective (more explanation on this latter).
the researchers possibly knew this was a controversial topic, so they analysed the sh!t out of these data, and no matter which way they analyses it, there was always a link between fluoride levels and child IQ scores.
Given this excellent study’s general finding supports RFK Jnr’s prediction, it seems that reducing fluoride levels might be something that gets lowered in the USA during the next 4 years.
So let’s throw this study in the blender and look at the …
Devil in the Details
I always encourage you to search for meta-analyses when you wish to know the answer to a question. But technically, you can get a very similar answer if you find a ‘systematic review’ on the topic. Indeed, systematic reviews are easier to read.
But the advantage of a meta-analysis is that it provides quantification to the data. That is, you’ll not only find if something is likely to be true or not, but by how much it is true (in other words, the effect size).
Finally, such meta-analyses require an assessment of the studies’ quality. Of note in this new meta-analysis, 52 of the 74 studies were rated as having a high risk of bias.
So let’s have a look at the results - especially the results from the high-quality studies …
First, this table categorises studies into those that looked at fluoride in drinking water (p.s. fluoride is also in some food and beverages) - and furthermore anlayses what happens when you look at quality studies.
It’s safe to conclude that when fluoride levels are >1.5 mg/Litre that there is a significant link - but when they’re <1.5 mg/L then there is no link.
So what are the levels of fluoride in drinking water in the US?
Before we get to that, first look at how many IQ points kids lose when fluoride levels are too high …
They lose just over one IQ point per mg/L change.
This then begs the ultimate question -
How do we apply these findings to the real world?
This is important question, because research is intended to expand our knowledge and improve our lives - so …
Does this meta-analysis provide strong support to lower fluoride levels in the USA?
I am going to assume RFK Jnr intends to improve the lives of children in the US.
So let’s look at the ‘generalisation’ or ‘meaning’ of this study’s results for kid’s in the USA.
Levels of fluoride in drinking water are recommended to be <1.5 mg/L (the recommendations are between 0.7 to 1.5 mg/L).
Of the 74 studies analysed in this excellent study, none were conducted in the USA. China made up the bulk of the studies with 45, followed by Iran (N=4) and Mexico (N=4). With China having 60% of their studies in this meta-analysis, it could be argued that these findings apply well to the Chinese population.
The majority of studies used quick-and-dirty measures of IQ - which is VERY different to the gold-standard measurement (eg, WISC), which 13 studies used. This means the precision of these quick and dirty measures are variable.
Does one IQ point matter?
Now I’m gonna switch my ‘research-hat’ with my ‘clinical-hat’.
IQ has a mean score of 100 and a standard deviation of 15 - meaning two standard deviations above the mean is where the gifted people lie (ie, mean of 100 + 2SDs x 15 = an IQ of 130).
Conversely, two SDs below the mean is considered the line for disability (ie, an IQ of 70).
I would say that the one IQ point from this study does NOT matter for the vast majority of the population.
Whilst some may argue that one IQ point could determine whether a child is gifted or not, I still say it doesn’t matter. In the circumstances when a child scores 130 or more, it doesn’t mean the child automatically goes up a grade in school - because there needs to be a discussion about the child’s social capabilities and their friendship network. More times than not, the child stays in the same level and is offered more challenging work. But this can occur even for a child with an IQ of 129, 128, 127, etc. So at this pointy end of the continuum, one IQ point doesn’t matter.
But one IQ point can matter when determining if a child scores 70. This can mean the difference between funding or not to assist with their schooling.
But also consider this - I taught trainee psychologists to never report the IQ score to a parent. The reason being that there are so many factors that can affect even the gold-standard IQ measurement (eg, anxiety, how the child slept, the child’s motivation etc) that it is common practice to report a range or percentile.
In other words, your child scored 98-103, which is around the 45th percentile (ie, out of 100 kids, they scored 45th).
And finally, consider this - IQ changes with development.
But not just by itself - but through education, life experience, and focused education interventions that results from an IQ test.
Conclusions?
A very tiny percentage of the US child population could be affected by this one IQ point - the majority above and below an IQ score of 70 won’t.
Then again, with the current US government’s fucked up attitude towards Diversity, Equity and Inclusion (DEI) - which happens to include people with disabilities - RFK Jnr cannot claim on the one hand that reducing fluoride in drinking water will improve US children’s IQ, and on the other hand be a part of a government who makes wankerish statements that affect those with an IQ disability (amongst others).
Even if you improve all kids’ IQs by 1 point, there will always be kids on that disability line. What those kids need - as well as their families - is support in all forms.
Financial support.
Practical support.
Emotional support.
And just because RFK Jnr aligned with the over-arching findings from this meta-analysis (ie, an inverse relationship between fluoride drinking levels and child IQ scores) that doesn’t mean he’s right about other claims.
In fact, this fluoride claim is stretching the truth.
The Devil’s in the details …
Prof MG
p.s. - whilst I became somewhat of an expert on child IQ assessment, I’m not a dentist - and thus I won’t speak to the prevention of tooth decay when there is fluoride in drinking water. I’ll leave that up to the dentists …