9 ms·

Childhood intelligence in relation to major causes of death in 68 year follow-up

114 points by gwern 9y ago

vixen99 9y ago
It would seem reasonable to suppose that much of this is related to the known association between delayed gratification (self control) and intelligence (the marshmallow experiment described as for instance in https://jamesclear.com/delayed-gratification https://jamesclear.com/delayed-gratification)?
- truculation 9y ago
  And yet intelligent people are said to use more drugs: https://www.psychologytoday.com/blog/the-scientific-fundamentalist/201011/why-intelligent-people-use-more-drugs https://www.psychologytoday.com/blog/the-scientific-fundamen...
  - icebraining 9y ago
    It's not clear if they controlled for other factors. It may be that they simply have more money to buy them.
    - pantalaimon 9y ago
      Drugs are not that expensive, but not everyone is so curious to try them.
- deleted 9y ago
  [deleted]
jedberg 9y ago
Did they control for economic class? If all the smarter people are richer, it would follow that they lived healthier lives with better access to medical care.
- keketi 9y ago
  Yes. From the linked page: > Sensitivity analyses on a representative subsample of the cohort observed only small attenuation of the estimated effect of intelligence (by 10-26%) after adjustment for potential confounders, including three indicators of childhood socioeconomic status. In a replication sample from Scotland, in a similar birth year cohort and follow-up period, smoking and adult socioeconomic status partially attenuated (by 16-58%) the association of intelligence with outcome rates.
  - wjnc 9y ago
    If you control for positively correlated variables, the results are more dramatic right? Higher intelligence leads to lower death And higher intelligence to higher income then lower death. So actuarial effects multiply.
- lox 9y ago
  My first question too: > In the absence of individual level data on socioeconomic status in the full SMS1947, we used school attended as a proxy measure to adjust for potential confounding by background socioeconomic status. A Scottish cohort study has shown that primary school has moderate correlation with paternal social class.
- pacaro 9y ago
  All participants lived in a society with socialized healthcare built around a “free at the point of service” model. That’s not to say that socioeconomic status doesn’t play a part (as other commenters have noted) but the difference in access to healthcare due to wealth is relatively small in the UK in general
  - DanBC 9y ago
    There are still wide health inequalities in the UK. Poor people eat worse food; don't get as much exercise; and smoke more. You can predict average life expectancy by post-code, and that's based on socio-economic factors.
roryisok 9y ago
Interesting that suicide had a weak correlation. Intelligence obviously has little bearing on depression
- nopassrecover 9y ago
  Or intelligent people may be more likely to apply cognitive techniques (perhaps they experience depression earlier and/or more commonly which may build resilience) and/or may be more likely to seek professional advice (e.g. because they see the value, move in circles in which it is more acceptable, or make more money and can afford to).
- Sharlin 9y ago
  How is that obvious?
- mercer 9y ago
  I'm not sure how you got to 'obviously'. Could you elaborate?
  - roryisok 9y ago
    Does "weak correlation" not mean that there was very little difference either way? I just meant this study seems to show that suicide is unaffected by intelligence. Either I read it wrong or I worded my content badly but I was just trying to draw a conclusion from what I thought the data said
- posterboy 9y ago
  "Suicide" is simply too rare, and too broad a category. Is not using a seat belt suicide? Is a heroin overdose? Is standing on a cliff to estimate what it would be like to jump and loosing ballance at the thought of it? How many suicides were there in the 60000 studied, perhaps 10? That's not enough to derive a meaningful result, I think. Edit: My estimate would be roughly correct, sad enough, ignoring my doubts on suicide as a cultural rather than medical category: http://news.bbc.co.uk/2/hi/uk_news/scotland/5297916.stm http://news.bbc.co.uk/2/hi/uk_news/scotland/5297916.stm
kelnage 9y ago
I can’t find any evidence of whether they controlled for obesity (which is certainly believed to be a factor is several of the diseases that a correlation was found for). But other than that, I’d say that it is a very interesting study.
- danieltillett 9y ago
  They can't as they were looking at death records.
- TangoTrotFox 9y ago
  Low adolescent IQ is a strong predictor for obesity later in life. [1] So I'm not sure how or why you'd want to control for obesity. You could be looking at a comorbid effect. Low IQ -> obesity -> early death. [1] - http://circ.ahajournals.org/content/124/Suppl_21/A12601.short http://circ.ahajournals.org/content/124/Suppl_21/A12601.shor...
maltalex 9y ago
Interesting. I wonder whether the Flynn effect (increase in IQ in the general population over time [0]) can therefore explain at least some of the increase in longevity in the 20th century. [0]: https://en.wikipedia.org/wiki/Flynn_effect https://en.wikipedia.org/wiki/Flynn_effect
- danieltillett 9y ago
  Not directly, but it is quite possible the Flynn effect and the increase in longevity have a common cause. Shame the Flynn effect ended a few decades ago.
  - RubenSandwich 9y ago
    Do you have a source on the Flynn effect ending?
    - danieltillett 9y ago
      Wiki has a whole section on it [0]. 1. https://en.wikipedia.org/wiki/Flynn_effect https://en.wikipedia.org/wiki/Flynn_effect
      - RubenSandwich 9y ago
        Thanks, never saw that before.
  - posterboy 9y ago
    This kind of linear thinking is too simplistic. Health will boost intelligence and vice versa in a non-linear fashion, if I am any judge, so an extrinsic impuls doesn't preclude intrinsic causation.
pjc50 9y ago
> Participants 33 536 men and 32 229 women who were participants in the Scottish Mental Survey of 1947 (SMS1947) and who could be linked to cause of death data up to December 2015. > In this prospective cohort study, all individuals born in Scotland in 1936 and registered at school in Scotland in 1947 were targeted for tracing and subsequent data linkage to death certificates Hard to get a more comprehensive population study than that.
amelius 9y ago
I'd love to see the relation between IQ and happiness.
- Neil44 9y ago
  I imagine it would be a negative one!
  - Moodles 9y ago
    Possibly, but I'm not so sure. If you're smart, you will make more money, and yes of course money doesn't make you actually happy etc etc, but studies have shown it actually does up to a point (or, at least, money gets rid of things which would otherwise make you unhappy, such as medical care, lack of new things, etc). It would certainly be interesting to see a study on this.
    - amelius 9y ago
      On the other hand: http://www.independent.co.uk/news/health/intelligence-mental-illness-iq-study-findings-depression-a8005801.html http://www.independent.co.uk/news/health/intelligence-mental...
    - pbhjpbhj 9y ago
      >If you're smart, you will make more money // On average, just being 'smart' isn't sufficient.
      - Moodles 9y ago
        I would be surprised if there's not a correlation between intelligence and average salary. Is there a study on this?
- danieltillett 9y ago
  There may not be one, but a high IQ can enable you to have a more comfortable misery.
- 9y ago
paulpauper 9y ago
Figure 4⇓ shows the associations between groupings of childhood intelligence score (10ths or quarters) and deaths related to 15 specific cancers. About half of these showed inverse patterns of association with a degree of linearity, including cancers of the oesophagus, colon or rectum, stomach, liver, lung, kidney, bladder, and blood. The strongest association was evident for death related to lung cancer: the risk in the highest performing 10th of childhood intelligence was reduced by two thirds compared with the lowest performing 10th. Cancers showing negligible or irregular associations with childhood mental ability included mouth, pancreas, skin, ovaries, breast (women only), prostate (men only), and brain or central nervous system. The problem is higher IQ mean means a healthier lifestyle, which is what protects against cancer, not genes that give rise to high IQ itself. That's why the effect is strongest for smoking, because less intelligent people may be more likely to smoke. Same for drinking, which increases odds of stomach and esophagus and liver cancer. Somewhat disappointing becase it confimrs that we have already suspected, whic his a helathier lifestyle means less risk of certain cancers. Not surprisingly, the effect is non-existent for brain cancers.
- tziki 9y ago
  >The problem is higher IQ mean means a healthier lifestyle, which is what protects against cancer, not genes that give rise to high IQ itself. Based on what, exactly?
  - slx26 9y ago
    I assume he's talking about a correlation, and probably not strictly limited to a healthier lifestyle, but also to higher income (on average), which provides potentially better access to healthcare, etc.
    - projectramo 9y ago
      I think you can see the difference in these effects by the difference in deaths from smoking vs other cancers. So the reduction in - for instance - prostate cancer may be due to access to healthcare vs reduction in lunch cancer which might be a proxy for “smarter” decisions.
mysterypie 9y ago
Is there a way to express the figures in a more tangible way? Something like: the smartest 10% lived N months longer than the dumbest 10%. And with respect to specific cause of death, does a hazard ratio of 0.72 for respiratory disease mean that respiratory disease killed 72 of the smartest 10% each year for 100 of the dumbest 10%?
brwsr 9y ago
There is so much more to this. Inequality, poverty.. Poverty hinders proper brain development and wiring. Life expectance in London is 25 years less for the poor! Economy rules! It is not popular info, but for those interested: https://youtu.be/GvkchZADaaA https://youtu.be/GvkchZADaaA
cimmanom 9y ago
For a community that likes to point out all the time that correlation is not causation, a lot of the posts so far seem to be making assumptions about causative direction. But why should we assume that just because they're correlated in this study, high IQ causes longer life expectancy? Maybe the same early childhood circumstances (such as better nutrition) that led to measurably higher IQ also led to individuals being healthier / more robust later in life. Maybe exposure to certain toxins that decrease IQ (say, lead) also tends to make certain cancers more likely.
- Houshalter 9y ago
  Well adoption studies show that environment doesn't matter much to IQ. Kids raised in the poorest families didn't have higher IQs than kids raised in the richest families (http://sci-hub.la/10.1007/s10519-007-9142-7 http://sci-hub.la/10.1007/s10519-007-9142-7). Adopted siblings have little correlation in IQ (https://www.ncbi.nlm.nih.gov/pubmed/21807642 https://www.ncbi.nlm.nih.gov/pubmed/21807642). And intervention programs to increase IQ in disadvantaged populations always fail (https://www.sciencedirect.com/science/article/pii/S016028961500135X https://www.sciencedirect.com/science/article/pii/S016028961...). Lung cancer is one of the biggest correlation found here. And smoking is pretty genetic (https://www.ncbi.nlm.nih.gov/pubmed/15971021 https://www.ncbi.nlm.nih.gov/pubmed/15971021). Other things might be affected by diet and BMI, but that's also highly genetic. This study also controlled for socioeconomic status.
  - fao_ 9y ago
    > Well adoption studies show that environment doesn't matter much to IQ. Really? I remember a few adoption study where they found the opposite: They measured the IQs of genetically identical twins that were adopted into different families, and found that family environment mattered a hell of a lot. I can't find the study that I remember, but here are some adjacent studies that have done similar things with similar results: http://sciencenordic.com/adopted-children-have-higher-iqs-their-non-adopted-siblings http://sciencenordic.com/adopted-children-have-higher-iqs-th... https://www.ncbi.nlm.nih.gov/pubmed/6872626 https://www.ncbi.nlm.nih.gov/pubmed/6872626 http://www.pnas.org/content/112/15/4612 http://www.pnas.org/content/112/15/4612
pharrington 9y ago
Here's my hot take: genes that cause a given nervous system to be better than typical at making decisions that lead to better outcomes for the organism will cause the organism to be better than typical at cell and DNA repair.

114 points by gwern 9y ago

It would seem reasonable to suppose that much of this is related to the known association between delayed gratification (self control) and intelligence (the marshmallow experiment described as for instance in https://jamesclear.com/delayed-gratification https://jamesclear.com/delayed-gratification)?

truculation 9y ago
And yet intelligent people are said to use more drugs: https://www.psychologytoday.com/blog/the-scientific-fundamentalist/201011/why-intelligent-people-use-more-drugs https://www.psychologytoday.com/blog/the-scientific-fundamen...
- icebraining 9y ago
  It's not clear if they controlled for other factors. It may be that they simply have more money to buy them.
  - pantalaimon 9y ago
    Drugs are not that expensive, but not everyone is so curious to try them.
deleted 9y ago
[deleted]

jedberg 9y ago

Did they control for economic class? If all the smarter people are richer, it would follow that they lived healthier lives with better access to medical care.

keketi 9y ago
Yes. From the linked page: > Sensitivity analyses on a representative subsample of the cohort observed only small attenuation of the estimated effect of intelligence (by 10-26%) after adjustment for potential confounders, including three indicators of childhood socioeconomic status. In a replication sample from Scotland, in a similar birth year cohort and follow-up period, smoking and adult socioeconomic status partially attenuated (by 16-58%) the association of intelligence with outcome rates.
- wjnc 9y ago
  If you control for positively correlated variables, the results are more dramatic right? Higher intelligence leads to lower death And higher intelligence to higher income then lower death. So actuarial effects multiply.
lox 9y ago
My first question too: > In the absence of individual level data on socioeconomic status in the full SMS1947, we used school attended as a proxy measure to adjust for potential confounding by background socioeconomic status. A Scottish cohort study has shown that primary school has moderate correlation with paternal social class.
pacaro 9y ago
All participants lived in a society with socialized healthcare built around a “free at the point of service” model. That’s not to say that socioeconomic status doesn’t play a part (as other commenters have noted) but the difference in access to healthcare due to wealth is relatively small in the UK in general
- DanBC 9y ago
  There are still wide health inequalities in the UK. Poor people eat worse food; don't get as much exercise; and smoke more. You can predict average life expectancy by post-code, and that's based on socio-economic factors.

roryisok 9y ago

Interesting that suicide had a weak correlation. Intelligence obviously has little bearing on depression

nopassrecover 9y ago
Or intelligent people may be more likely to apply cognitive techniques (perhaps they experience depression earlier and/or more commonly which may build resilience) and/or may be more likely to seek professional advice (e.g. because they see the value, move in circles in which it is more acceptable, or make more money and can afford to).
Sharlin 9y ago
How is that obvious?
mercer 9y ago
I'm not sure how you got to 'obviously'. Could you elaborate?
- roryisok 9y ago
  Does "weak correlation" not mean that there was very little difference either way? I just meant this study seems to show that suicide is unaffected by intelligence. Either I read it wrong or I worded my content badly but I was just trying to draw a conclusion from what I thought the data said
posterboy 9y ago
"Suicide" is simply too rare, and too broad a category. Is not using a seat belt suicide? Is a heroin overdose? Is standing on a cliff to estimate what it would be like to jump and loosing ballance at the thought of it? How many suicides were there in the 60000 studied, perhaps 10? That's not enough to derive a meaningful result, I think. Edit: My estimate would be roughly correct, sad enough, ignoring my doubts on suicide as a cultural rather than medical category: http://news.bbc.co.uk/2/hi/uk_news/scotland/5297916.stm http://news.bbc.co.uk/2/hi/uk_news/scotland/5297916.stm

kelnage 9y ago

I can’t find any evidence of whether they controlled for obesity (which is certainly believed to be a factor is several of the diseases that a correlation was found for). But other than that, I’d say that it is a very interesting study.

danieltillett 9y ago
They can't as they were looking at death records.
TangoTrotFox 9y ago
Low adolescent IQ is a strong predictor for obesity later in life. [1] So I'm not sure how or why you'd want to control for obesity. You could be looking at a comorbid effect. Low IQ -> obesity -> early death. [1] - http://circ.ahajournals.org/content/124/Suppl_21/A12601.short http://circ.ahajournals.org/content/124/Suppl_21/A12601.shor...

maltalex 9y ago

Interesting. I wonder whether the Flynn effect (increase in IQ in the general population over time [0]) can therefore explain at least some of the increase in longevity in the 20th century. [0]: https://en.wikipedia.org/wiki/Flynn_effect https://en.wikipedia.org/wiki/Flynn_effect

danieltillett 9y ago
Not directly, but it is quite possible the Flynn effect and the increase in longevity have a common cause. Shame the Flynn effect ended a few decades ago.
- RubenSandwich 9y ago
  Do you have a source on the Flynn effect ending?
  - danieltillett 9y ago
    Wiki has a whole section on it [0]. 1. https://en.wikipedia.org/wiki/Flynn_effect https://en.wikipedia.org/wiki/Flynn_effect
    - RubenSandwich 9y ago
      Thanks, never saw that before.
- posterboy 9y ago
  This kind of linear thinking is too simplistic. Health will boost intelligence and vice versa in a non-linear fashion, if I am any judge, so an extrinsic impuls doesn't preclude intrinsic causation.

pjc50 9y ago

> Participants 33 536 men and 32 229 women who were participants in the Scottish Mental Survey of 1947 (SMS1947) and who could be linked to cause of death data up to December 2015. > In this prospective cohort study, all individuals born in Scotland in 1936 and registered at school in Scotland in 1947 were targeted for tracing and subsequent data linkage to death certificates Hard to get a more comprehensive population study than that.

amelius 9y ago

I'd love to see the relation between IQ and happiness.

Neil44 9y ago
I imagine it would be a negative one!
- Moodles 9y ago
  Possibly, but I'm not so sure. If you're smart, you will make more money, and yes of course money doesn't make you actually happy etc etc, but studies have shown it actually does up to a point (or, at least, money gets rid of things which would otherwise make you unhappy, such as medical care, lack of new things, etc). It would certainly be interesting to see a study on this.
  - amelius 9y ago
    On the other hand: http://www.independent.co.uk/news/health/intelligence-mental-illness-iq-study-findings-depression-a8005801.html http://www.independent.co.uk/news/health/intelligence-mental...
  - pbhjpbhj 9y ago
    >If you're smart, you will make more money // On average, just being 'smart' isn't sufficient.
    - Moodles 9y ago
      I would be surprised if there's not a correlation between intelligence and average salary. Is there a study on this?
danieltillett 9y ago
There may not be one, but a high IQ can enable you to have a more comfortable misery.
9y ago

paulpauper 9y ago

Figure 4⇓ shows the associations between groupings of childhood intelligence score (10ths or quarters) and deaths related to 15 specific cancers. About half of these showed inverse patterns of association with a degree of linearity, including cancers of the oesophagus, colon or rectum, stomach, liver, lung, kidney, bladder, and blood. The strongest association was evident for death related to lung cancer: the risk in the highest performing 10th of childhood intelligence was reduced by two thirds compared with the lowest performing 10th. Cancers showing negligible or irregular associations with childhood mental ability included mouth, pancreas, skin, ovaries, breast (women only), prostate (men only), and brain or central nervous system. The problem is higher IQ mean means a healthier lifestyle, which is what protects against cancer, not genes that give rise to high IQ itself. That's why the effect is strongest for smoking, because less intelligent people may be more likely to smoke. Same for drinking, which increases odds of stomach and esophagus and liver cancer. Somewhat disappointing becase it confimrs that we have already suspected, whic his a helathier lifestyle means less risk of certain cancers. Not surprisingly, the effect is non-existent for brain cancers.

tziki 9y ago
>The problem is higher IQ mean means a healthier lifestyle, which is what protects against cancer, not genes that give rise to high IQ itself. Based on what, exactly?
- slx26 9y ago
  I assume he's talking about a correlation, and probably not strictly limited to a healthier lifestyle, but also to higher income (on average), which provides potentially better access to healthcare, etc.
  - projectramo 9y ago
    I think you can see the difference in these effects by the difference in deaths from smoking vs other cancers. So the reduction in - for instance - prostate cancer may be due to access to healthcare vs reduction in lunch cancer which might be a proxy for “smarter” decisions.

mysterypie 9y ago

Is there a way to express the figures in a more tangible way? Something like: the smartest 10% lived N months longer than the dumbest 10%. And with respect to specific cause of death, does a hazard ratio of 0.72 for respiratory disease mean that respiratory disease killed 72 of the smartest 10% each year for 100 of the dumbest 10%?

brwsr 9y ago

There is so much more to this. Inequality, poverty.. Poverty hinders proper brain development and wiring. Life expectance in London is 25 years less for the poor! Economy rules! It is not popular info, but for those interested: https://youtu.be/GvkchZADaaA https://youtu.be/GvkchZADaaA

cimmanom 9y ago

For a community that likes to point out all the time that correlation is not causation, a lot of the posts so far seem to be making assumptions about causative direction. But why should we assume that just because they're correlated in this study, high IQ causes longer life expectancy? Maybe the same early childhood circumstances (such as better nutrition) that led to measurably higher IQ also led to individuals being healthier / more robust later in life. Maybe exposure to certain toxins that decrease IQ (say, lead) also tends to make certain cancers more likely.

Houshalter 9y ago
Well adoption studies show that environment doesn't matter much to IQ. Kids raised in the poorest families didn't have higher IQs than kids raised in the richest families (http://sci-hub.la/10.1007/s10519-007-9142-7 http://sci-hub.la/10.1007/s10519-007-9142-7). Adopted siblings have little correlation in IQ (https://www.ncbi.nlm.nih.gov/pubmed/21807642 https://www.ncbi.nlm.nih.gov/pubmed/21807642). And intervention programs to increase IQ in disadvantaged populations always fail (https://www.sciencedirect.com/science/article/pii/S016028961500135X https://www.sciencedirect.com/science/article/pii/S016028961...). Lung cancer is one of the biggest correlation found here. And smoking is pretty genetic (https://www.ncbi.nlm.nih.gov/pubmed/15971021 https://www.ncbi.nlm.nih.gov/pubmed/15971021). Other things might be affected by diet and BMI, but that's also highly genetic. This study also controlled for socioeconomic status.
- fao_ 9y ago
  > Well adoption studies show that environment doesn't matter much to IQ. Really? I remember a few adoption study where they found the opposite: They measured the IQs of genetically identical twins that were adopted into different families, and found that family environment mattered a hell of a lot. I can't find the study that I remember, but here are some adjacent studies that have done similar things with similar results: http://sciencenordic.com/adopted-children-have-higher-iqs-their-non-adopted-siblings http://sciencenordic.com/adopted-children-have-higher-iqs-th... https://www.ncbi.nlm.nih.gov/pubmed/6872626 https://www.ncbi.nlm.nih.gov/pubmed/6872626 http://www.pnas.org/content/112/15/4612 http://www.pnas.org/content/112/15/4612

pharrington 9y ago

Here's my hot take: genes that cause a given nervous system to be better than typical at making decisions that lead to better outcomes for the organism will cause the organism to be better than typical at cell and DNA repair.