Gifted Issues Discussion homepage Forums General Discussion Can IQ be improved?

Lol, exactly. We live in a 100yo place with a certain amount of flaking paint, but blood lead level testing etc. is unknown here in the UK, and I have no idea what DS's levels have ever been. I sometimes feel uneasy about this, and yet, maybe it's for the best!

On top of the very valid points everyone else has made I also have to question whether, even if we believe that breastfeeding might give you x points, and good nutrition x points, etc whether those points come from correlation not causation and are in fact roughly speaking the SAME few points. No-one has researched all those things together or in their various combinations, each has been (possibly rather dubiously) looked at in isolation. You can't then go well "study" #1 + "study"#2 + "study" #3 = 15 points!

I would think that for the most part the extended breastfeeders are also more likely to be careful with other nutritional needs, also more likely to provide a rich environment, etc. You could include someone who does all three into three different studies for just one of those behaviours and pick up their "extra" 5 points in all three studies(which may well be genetic). You can't then say that their child would have been 15 points worse off if they had not done any one of those three things.

they did do the study, and found there was a gene involved with the susceptibility to harm from formula. That gene had better not be related to susceptibility to IGT or PCOS, is all I can say.

http://www.physorg.com/news113505546.html

Very interesting, I'd missed that. Here's the
full paper.

However, the Wikipedia article on FADS2 (the gene concerned) says that several later studies failed to replicated this finding. One issue that may be relevant is how "breastfed" is defined - e.g., does it mean ever given breastmilk, or exclusively breastfed to 6 months, or what? The original study doesn't seem, on a quick read, to say. Maybe there's a conventional definition that the reader is supposed to know they used, but if not, and if the original and the replicating studies used different definitions, that could be important.

I haven't stated myself very clearly it seems. I was trying to say that it seems to me that in books like the one the OP mentioned, the author will look at 5 different studies of things that might raise IQ and then claim that if you do all 5 then you will get cumulative increases in IQ.

I question the validity of some of those studies, but I also very much doubt that you can say you can get x points for breastfeeding, another x points for a prepared environment and a further x points for a chemical free house. Even assuming the studies are sound, chances are that the same subjects who are extended breastfeeders might also be the low chemical householders and the prepared environment people and their kids higher IQ may be genetic. You could participate in all three studies and show that your child had an extra 5 points in each study - but your child is not 15 points higher for having done the three studies. Until someone comes up with a sound study of combined factors, if that is even possible, then I am very dubious of lists of things you can do for combined positive outcomes (even if I believe the individual studies, which in many cases I am not sure that I do).

I probably didn't explain that any better the second time.

Your point's very interesting, MumOfThree, and I didn't comment on it because I started down a trail of thinking about what you said and didn't get to a good resting point! My first intuition was: "I dare say in practice you're right, because it's so difficult to control for confounding factors, but I *think* that if the studies in question were done properly so as to show causation, not just correlation, your argument would not apply (or not exactly...)."

But then I started to actually do the mathematics and came to some surprising and amusing conclusions... And confused myself utterly, so let's see who else I can confuse :-) :-)

Let's consider a simplified situation. Suppose that we had uncontroversial, cast-iron evidence that
(a) using acrylic nappies raises IQ by 5 points ("acrylic" for short)
(b) giving a daily dose of cocaine raises IQ by 5 points ("cocaine" for short).
For causation to have been shown, which we're assuming, it has to be the case that, if you take groups of families with babies who are equally likely to have any characteristic known or suspected to affect IQ, except that one group uses acrylic and the other doesn't, then the acrylic group has babies with IQs on average 5 points higher. Similarly for cocaine. If the studies haven't shown this - if they haven't controlled for all plausible confounders - then by definition the studies are not sound. We're assuming they are.

Now, which of these connections, acrylic or cocaine, was suspected first? Let's suppose that the news about the possible benefit of acrylic broke first. For this investigation, it will suffice to imagine that, to everyone's surprise, the situation is very simple: every baby's IQ is raised by exactly 5 points compared to where it would otherwise have been expected to be, provided the baby wears an acrylic nappy. This is so convincing that noone questions it any more...

At this stage, nobody gives their baby cocaine; that wonder-factor hadn't yet been suspected. Later, giving your baby cocaine becomes fashionable and people think about studying it. Now, any study of cocaine that doesn't control for acrylic is by definition unsound. IOW, by assumption, we have studies that show that, even when the cocaine-using group and the non-cocaine using group have the same proportion of acrylic-users, the cocaine-using group has higher IQ. Is this consistent with there being no additional benefit of using cocaine if you already use acrylic?

Well, yes: it just has to be the case that there's a larger than 5 point effect on the non-acrylics, to account for the 0 point effect on the acrylics. Suppose for simplicity that 50% of the population uses acrylic at this point (and that the study's groups are representative in this respect). If non-acrylic + cocaine gives a 10 point advantage compared to neither, and acrylic + cocaine gives only the 5 point advantage they already had for acrylic, we're done: average IQ gain of 5 points for cocaine will be what we see when comparing the study groups, and will be what holds over the whole population.

Note the strange situation we've cooked up. Suppose the no-acrylic no-cocaine baseline IQ is 100. We've got acrylic no-cocaine and acrylic + cocaine both at 105, and we've got no-acrylic + cocaine at 110. Just so long as hardly anyone uses cocaine (the situation that pertained when the acrylic research was done) both acrylic and cocaine, separately, are genuinely causing a 5 point IQ increase averaged across the whole population, as stipulated: but the way to give your child the highest possible IQ is to *not* use acrylic but use cocaine.

As more and more people start using cocaine, the average benefit of using acrylic diminishes, until when 50% of people are using cocaine, the average effect of using acrylic is 0, and when 100% of people are using cocaine, we find that using acrylic (quite genuinely!) causes an average of a 5 point drop in your baby's IQ.

Now, as laid out, because the cocaine study is controlling for acrylic, this strange situation will, hopefully, be noticed and remarked on. (But maybe not - if all they do is to make sure the cocaine and no-cocaine groups have the same proportion of acrylic users, and they don't study the acrylic and non-acrylic users separately (maybe they haven't the power) they will still have controlled for acrylic, but they won't spot this effect.) But it illustrates the difficulty in investigating multi-factorial effects, and also the difficulty of applying research in a different time or place to where it was done.

If you consider a slightly different scenario, in which the same reality holds, but the research pattern is different, it could happen like this:

- 50% of people use acrylic, but only one group of researchers suspects it might matter. They do a study.

- 0.001% of people use cocaine, and only one group of researchers (not the same ones) think it might matter. They do a study.

Since the researchers are working independently and in ignorance of one another's work, neither controls for the other's factor. (Both control for all other known confounders, but that need not concern us: let us suppose that neither acrylic use nor cocaine use is correlated with any other confounder, nor with one another.) In our hypothesised reality, both studies will, quite rightly, find that their factor causes an average 5 point increase in IQ. And then maybe people like us who read both studies will come along and wonder whether or not you get a 10 point increase by doing both...

ETA: and to bring us back to reality, I wonder whether the study someone mentioned on playing string instruments controlled for breastfeeding, separate from the confounders of maternal IQ and eduction? It would be amusing, would it not, if playing a string instrument raises your IQ substantially but only if you weren't breastfed, so that actually, the optimal strategy for raising your baby's IQ is to formula feed and send them to Suzuki classes?

Science has advanced:

http://articles.latimes.com/2011/aug/10/news/la-heb-genetic-study-intelligence-20110809
Intelligence is in the genes, researchers report
August 10, 2011
By Eryn Brown
Los Angeles Times

Intelligence is in the genes, researchers reported Tuesday in the journal Molecular Psychology.

The international team, led by Ian Deary of the University of Edinburgh in Scotland and Peter Visscher of the Queensland Institute of Medical Research in Brisbane, Australia, compared the DNA of more than 3,500 people, middle aged and older, who also had taken intelligence tests. They calculated that more than 40% of the differences in intelligence among test subjects was associated with genetic variation.

The genome-wide association study, as such broad-sweep genetic studies are known, suggested that humans inherit much of their smarts, and a large number of genes are involved.

Booster Shots asked Deary to answer a few questions about the research. The following is an edited version of our questions and his emailed responses.

What exactly were you looking for when you looked at test subjects' genetic information?

We studied over 3,500 people. We looked at over 500,000 individual locations on the chromosomal DNA where people are known to differ. We looked at the association between those DNA differences and two types of intelligence. One type of intelligence was on-the-spot thinking (fluid intelligence) and the other was vocabulary (crystallized intelligence).

You wrote in your paper that 40% of the variation in crystallized intelligence and 51% of the variation in fluid intelligence is associated with genetic differences. How did you calculate those figures? And where does the rest of intelligence come from? Other genes, or environmental factors?

To estimate the proportion of variance associated with common genetic differences (in what are called single nucleotide polymorphisms, or SNPs) we used a new genetic statistics procedure invented by Professor Visscher and his colleagues in Brisbane, called GCTA. The rest of people's differences in those types of intelligence could come from genetic differences we were not able to capture, or from the environment.

Certainly, twin and adoption studies tell us that the environment makes an important contribution to intelligence differences throughout life, and especially in early childhood.

Is this the first time such a study has been attempted? How have scientists studied the relationship between genes and intelligence in the past?

There have been some studies looking at individual genes and sets of genes. And some smaller studies have been conducted with coarser genetic sweeps. This is the first study to use thousands of people, half a million genetic variants and to apply this new GCTA procedure to
estimate the genetic contribution directly from the genes.

Why would it be surprising that intelligence is an inherited trait? Many people might say this seems obvious.

It is not surprising to find that intelligence differences have some genetic foundation. Twin and adoption studies have been suggesting that for decades. But those studies make assumptions -- for example that the environment is just as similar for non-identical twins as for identical twins -- and people have questioned those assumptions.

Here, we bypass all that and test the DNA. What is not at all obvious is what the genetic contribution is. From our results, we can suggest that a substantial amount of the genetic contribution to intelligence differences comes from many, many small effects from genetic variants that are in linked with common variants (SNPs).

<end of excerpt>

Here is the paper abstract:

http://www.ncbi.nlm.nih.gov/pubmed/21826061
Mol Psychiatry. 2011 Aug 9. doi: 10.1038/mp.2011.85. [Epub ahead of print]
Genome-wide association studies establish that human intelligence is highly heritable and polygenic.
Davies G, Tenesa A, Payton A, Yang J, Harris SE, Liewald D, Ke X, Le Hellard S, Christoforou A, Luciano M, McGhee K, Lopez L, Gow AJ, Corley J, Redmond P, Fox HC, Haggarty P, Whalley LJ, McNeill G, Goddard ME, Espeseth T, Lundervold AJ, Reinvang I, Pickles A, Steen VM, Ollier W, Porteous DJ, Horan M, Starr JM, Pendleton N, Visscher PM, Deary IJ.
Source
Department of Psychology, University of Edinburgh, Edinburgh, UK.
Abstract
General intelligence is an important human quantitative trait that accounts for much of the variation in diverse cognitive abilities. Individual differences in intelligence are strongly associated with many important life outcomes, including educational and occupational attainments, income, health and lifespan. Data from twin and family studies are consistent with a high heritability of intelligence, but this inference has been controversial. We conducted a genome-wide analysis of 3511 unrelated adults with data on 549&#8201;692 single nucleotide polymorphisms (SNPs) and detailed phenotypes on cognitive traits. We estimate that 40% of the variation in crystallized-type intelligence and 51% of the variation in fluid-type intelligence between individuals is accounted for by linkage disequilibrium between genotyped common SNP markers and unknown causal variants. These estimates provide lower bounds for the narrow-sense heritability of the traits. We partitioned genetic variation on individual chromosomes and found that, on average, longer chromosomes explain more variation. Finally, using just SNP data we predicted &#8764;1% of the variance of crystallized and fluid cognitive phenotypes in an independent sample (P=0.009 and 0.028, respectively). Our results unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation, and are consistent with many genes of small effects underlying the additive genetic influences on intelligence.

Ah, interesting, thanks for posting that Bostonian. Recent enough, though, that not only will I not beat myself up for not having known about it, but also, I will continue to regard the book under discussion as snakeoil, because at the time the book was written, we didn't know with any confidence what genes were important. (And now, it looks as though there are so many genes involved, each with low individual importance, that you'd have to be showing that some environmental factor turned on many of them for that factor to have a measurable effect by doing so, probably.)

They say hindsight is 20/20.

Thanks for the laugh, PTP! You're a hoot!

I also think this is the more accurate way to phrase it.