14 ms·

From the conclusion: "The scale of the observed deficits was not insubstantial; the 0.57 SD global composite score reduction for the hospitalised with ventilat

From the conclusion: "The scale of the observed deficits was not insubstantial; the 0.57 SD global composite score reduction for the hospitalised with ventilator sub-group was equivalent to the average 10-year decline in global performance between the ages of 20 to 70 within this dataset. It was larger than the mean deficit of 512 people who indicated they had previously suffered a stroke (-0.40SDs) and the 1016 who reported learning disabilities (-0.49SDs). For comparison, in a classic intelligence test, 0.57 SDs equates to an 8.5-point difference in IQ."

redis_mlc 6y ago
> the hospitalised with ventilator sub-group So this affects almost nobody then, and is probably caused by the sedatives, immobilization and ventilator organ damage, aside from corona.
- fogihujy 6y ago
  Well, the fact that someone was uable to breathe on their own also suggests that the virus may have caused a lack of oxygen to the brain. In such circumstances brain damage is quite likely, and then the disease would indeed be the cause. Fortunately, the group of people that end up on ventilators is not really that large, and I can imagine minor brain damage would still be preferable to death in many of those cases. As a sibling commented, theeffects that won't start to manifest until a year or two has passed are more worrying. There's simply so much we don't know about this virus yet.
  - neuronic 6y ago
    People are unable to worry about or comprehend the effects that happen right NOW. I am a staunch believer in post-viral syndrome as I experienced it first hand following an Epstein-Barr infection (mono) but aside from a handful of researchers nobody cares at all. For most physicians, it isn't even within the realm of possibilities when you come to them with random maladies. Boom, now you have anxiety because that's what they tell you when they don't know shit. There are so many bodily issues that arose after my Epstein-Barr infection, it's not funny at all. I can absolutely lead a normal life and am active and athletic. But things like autoimmune issues, persistent 15-year brain fog (I'd rather call it frosted glass layer) which randomly clears once a month to remind me how nice it is to be able to think straight, or full-body-numbing attacks in the middle of a gas station. The first 5 years after the disease I regularly felt like passing out. Later I just got dizzy and learned to control it using water and temperature changes (cold water in back of your neck!). I still took on the anxiety story and did something against it. It helped me in many ways but not with post-viral syndrome. It's real and it sucks but it's not being taken seriously at all. I am afraid, some COVID survivors are in for a new life which is different in just the right (but minor) ways to drive you insane. Body just doesn't feel the same as before.
    - rtp 6y ago
      It's amazing how people think a virus that lives latently in B cells and epithelial cells, and is strongly associated with various forms of cancer among a big helping of autoimmune disorders, is incapable of causing post-viral syndromes. No, it must be anxiety, of course! EDIT: Just because a disease makes you frustrated because you can't really do anything about it except empathize and listen, doesn't mean you can just slap the anxiety band-aid on it and call it a day.
      - neuronic 6y ago
        Correct, I don't expect doctors to cure me. I expect them to acknowledge that EBV could play a part here. But nope, just anxiety.
    - throwaway1092 6y ago
      > But things like autoimmune issues, persistent 15-year brain fog (I'd rather call it frosted glass layer) which randomly clears once a month to remind me how nice it is to be able to think straight I've been experiencing something similar for the past 5 years: brain fog (frosted glass is a much better way of putting it.) and some short term memory issues. The doctors put me through a battery of tests to find...that they could find no reason for my ailment. Curious to know what if anything has helped you the most. The 'randomly clearing' brain fog for a day happens to me maybe once every 3 months and it's both a blessing and a curse.
      - jokab 6y ago
        Sorry to hear this. I cured mine with a CPAP machine. I had to be tested with apnea twice bc the first one came out ok but i wasnt convinced. In any case, i hope you feel better
        throwaway1092 6y ago
        Thanks - already had/have a CPAP machine, so unfortunately that's not it.
    - 6y ago
- ghufran_syed 6y ago
  Not sure why you’re getting downvoted - here’s a page about post-intensive care syndrome, on the website of the society for critical care medicine, that’s concordant with what you said: https://www.sccm.org/MyICUCare/THRIVE/Post-intensive-Care-Syndrome https://www.sccm.org/MyICUCare/THRIVE/Post-intensive-Care-Sy...
  - noja 6y ago
    > Not sure why you’re getting downvoted I think he overlooked that the people were hospitalized and on ventilators because they had covid.
    - xd 6y ago
      But it's still an effect of the treatment. If you perform a study on people whom have been ill you're going to get results that show all the symptoms of illness.. the study could have been done with any illness and likely show cognitive decline.
      - shultays 6y ago
        symptoms of illness is the illness itself. Ignoring these symptoms of covid or results of the treatment is saying something like "bullets don't kill people, it ruptures blood vessels and you die due to loss of blood"
        srtjstjsj 6y ago
        You misunderstand the ambiguous wording. If you study only includes people with an illness, the illness itself is a confounder. The point is that if you have a non-ICU covid case, this research is unlikely to apply.
        jrumbut 6y ago
        It feels like we didn't read the same article, they break down numbers for people on ventilators but also hospitalized, non-ventilator patients all the way down to those who received no particular care. The findings were concerning to anyone who had it, they also mention cases where the cognitive deficit was the first reported symptom.
- xd 6y ago
  Also, I had a brief look over the paper but couldn't find anything to control for isolation since lockdown .. surely this would of had an effect on peoples cognition. On a side note, maybe it's just me but I keep seeing comments that don't follow a "politically" accepted view point, being down vote like yours.
  - w_t_payne 6y ago
    Maybe it's because this whole situation has been ridiculously politicized, to the point where it's difficult to have a rational fact-based discussion.
    - hejja 6y ago
      ...about anything. not just covid.
      - EForEndeavour 6y ago
        That's exactly what someone with your political beliefs would say!!
  - deleted 6y ago
    [deleted]
  - jmull 6y ago
    I don't know why people downvote things, but in this case I would hope it's because the previous comment was pretty superficial. Whether the covid causes cognitive decline through causing the use of a ventilator, sedatives, and immobilization or through some other mechanism still means it causes cognitive decline. So there's a basic logic flaw. Also, quite a large number of people have been put on ventilators due to covid-19, not "almost nobody". That's just an incorrect assertion. You'd like to attribute the downvoting to politics, but given the quality issues, I think that's a hard claim to support.
  - api 6y ago
    If isolation with a net connection for a few months dropped multiple IQ points, then all the shut-ins who do nothing but hang around on the Internet all day would be losing multiple tens of IQ points a year and would be functionally disabled by now.
- regularfry 6y ago
  The error bars overlap with the "hospitalised without ventilation" group. There's probably something else going on, and the authors do call out the known cognitive effects of hypoxia.
- nradov 6y ago
  There is some evidence that anesthetics can cause cognitive impairment. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443620/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443620/
  - kube-system 6y ago
    I was under the impression, at least as it pertained to the elderly, that GA is commonly known to be a significant risk.
    - nradov 6y ago
      Any type of long hospital stay frequently causes delirium among the elderly. GA makes it worse. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065676/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065676/
- simonh 6y ago
  Most of the impact seems to occur even without serious symptoms: >bio-positive cases who reported being ill with no breathing difficulties showed a 0.32SD magnitude cognitive deficit. My wife's hospital was full to the corridors with 'almost nobody's.
- paradox242 6y ago
  As other have already commented, they have already considered your theory in their analysis: "Consequently, the observation of post-infection deficits in the subgroup who were put on a ventilator was not surprising. Conversely, the deficits in cases who were not put on a ventilator, particularly those who remained at home, was unexpected." This effect on those hospitalized is not the primary thrust of their paper. Instead it was the observed effects on those who were not hospitalized or had mild to no respiratory symptoms. They raise many possibilities about why this may be the case and only assert that this effect at least proceeds into the recovery phase. I did not read any claims about this being permanent, broadly speaking.
- biolurker1 6y ago
  As many previous comments said, the article includes mild disease
st1x7 6y ago
Reduction equivalent to the cognitive decline of aging 10 years and larger than the cognitive decline of suffering a stroke? Sounds pretty substantial to me.
- minitech 6y ago
  “not insubstantial” :)
  - dempseye 6y ago
    This is a very English way of expressing oneself.
    - taneq 6y ago
      Well it's not unEnglish.
      - metalliqaz 6y ago
        "inflammable means flammable?"
        solarkraft 6y ago
        "all but"
    - deleted 6y ago
      [deleted]
    - julianlam 6y ago
      I also used to find this disturbing, but the way I have explained this to myself is -- Insignificant < 25% Not insignificant 25-50% Not significant 50-75% Significant > 75% Of course for each individual situation the numbers vary, and I use them simply to demonstrate that it's a matter of degrees, and not as binary as you may expect a typical "not" to be. It is the only double negative I have come to find useful.
sokoloff 6y ago
It’s equally as surprising to me the suggestion that the average decline in IQ from a stroke would be only 6 points or so.
- srtjstjsj 6y ago
  It's an average. Strokes can be very small and localized.
- treeman79 6y ago
  Varies a lot. I get a lot of minor strokes if I skip blood thinners for a week or so. At peak I’m a highly effective programmer. If I’ve had one recently, a “for loop” is a challenging concept. After a few days to weeks I’ll be back to near normal. Some symptoms last longer. Highly active Factor 5 Leiden, so I clot like crazy.
  - hderms 6y ago
    That sounds incredibly difficult. You must be a very strong and intelligent person.
    - treeman79 6y ago
      Thank you, yes beyond challenging. Mostly at this point because I work technical jobs and have no idea how to step down to lower role where periodic reduced intelligence is less of an issue.
- gen220 6y ago
  The impact of a stroke varies a lot with the kind of stroke, and the proximity of quality treatment. An awful stroke speedily treated by top doctors has the chance of imparting basically no change to cognitive function. Of the same token, not-the-worst strokes with mediocre care can ruin one's capacity to work. It's a really complicated medical event, with high variance in outcome. Strokes suck.
mrfusion 6y ago
I’d be curious to see this compared to people hospitalized on ventilators for other diseases. You’re not in good shape at that point and I’d expect all kinds of problems.
- usrusr 6y ago
  Does it matter though? The answer certainly depends on the context of the question: do we just want to assess the risks more precisely than the dead/alive boolean? No, it doesn't matter. Do we want to increase humanity's knowledge about how the virus affects our bodies? Yes, absolutely, if it's worse than standard damage of respirator episodes we'll want to know the "mechanisms" that we causing that extra damage.
  - mrfusion 6y ago
    If we’re being asked to give up our way of life, keep children out of school, damage mental health, give up essential freedoms. Then yes, I’d like to see it compared to existing diseases we’ve been living normally alongside for centuries!
- ineedasername 6y ago
  It's not (just) a matter of whether or not Covid is worse than other serious illnesses. It's that whatever existed already, Covid adds on top of that. So if there were X people that experienced significant health problems before, now there are X + Covid.
cltby 6y ago
I'm certainly not accusing you of this personally, but it's curious how selectively IQ is accepted/denied on this site. It's real enough for the purposes of covid policy, lead abatement, or whatever other fashionable environmental intervention. In just about every other case, flat out denialism.
- salicideblock 6y ago
  The general concern with IQ when used for policymaking, or with standardized "intelligence" tests in general, is that they can fail to account for environmental or cultural factors across individuals or populations. In both cases of covid and lead effects, the effect can be measured on the same population, and/or controlled for proxies of those factors (see "when controlling for age, gender, education level, income, racial-ethnic group and pre-existing medical disorders" in the article. So the general concern with the metric can be excluded.
  - cltby 6y ago
    Psychologists are just as adept at "controlling for age, gender, education level, income, racial-ethnic group." The validity of IQ was first established using within-group comparisons.
- bitdizzy 6y ago
  IQ is somewhat effective as a diagnostic tool for significant impairment and not much else. Your examples of where it is not contentious are exactly cases where you must measure impairments. Do you want to list some example contexts where you witness "flat out denialism"? In any case there is an important point: The variance of measured IQ for the same individual over time is very high. It's hard to extract a signal for that unless there's a severe effect being measured.
  - cltby 6y ago
    > IQ is somewhat effective as a diagnostic tool for significant impairment and not much else This places exactly zero constraints on the utility of IQ tests. Instead of asking why group A scores higher than group B, I can simply ask why group B is impaired relative to group A. Apparently that should be enough to convince you of the validity of the comparison. > The variance of measured IQ for the same individual over time is very high. The test-retest correlations of IQ batteries are typically in the 0.8-0.9 range. For example, the Wechsler test [1]. This makes IQ probably the single most reliable measure in the social sciences. Perhaps you're referring to the Wilson effect, but that's not at issue here. [1] https://images.pearsonclinical.com/images/pdf/wisciv/WISCIVTechReport2.pdf https://images.pearsonclinical.com/images/pdf/wisciv/WISCIVT...

redis_mlc 6y ago

> the hospitalised with ventilator sub-group So this affects almost nobody then, and is probably caused by the sedatives, immobilization and ventilator organ damage, aside from corona.

fogihujy 6y ago
Well, the fact that someone was uable to breathe on their own also suggests that the virus may have caused a lack of oxygen to the brain. In such circumstances brain damage is quite likely, and then the disease would indeed be the cause. Fortunately, the group of people that end up on ventilators is not really that large, and I can imagine minor brain damage would still be preferable to death in many of those cases. As a sibling commented, theeffects that won't start to manifest until a year or two has passed are more worrying. There's simply so much we don't know about this virus yet.
- neuronic 6y ago
  People are unable to worry about or comprehend the effects that happen right NOW. I am a staunch believer in post-viral syndrome as I experienced it first hand following an Epstein-Barr infection (mono) but aside from a handful of researchers nobody cares at all. For most physicians, it isn't even within the realm of possibilities when you come to them with random maladies. Boom, now you have anxiety because that's what they tell you when they don't know shit. There are so many bodily issues that arose after my Epstein-Barr infection, it's not funny at all. I can absolutely lead a normal life and am active and athletic. But things like autoimmune issues, persistent 15-year brain fog (I'd rather call it frosted glass layer) which randomly clears once a month to remind me how nice it is to be able to think straight, or full-body-numbing attacks in the middle of a gas station. The first 5 years after the disease I regularly felt like passing out. Later I just got dizzy and learned to control it using water and temperature changes (cold water in back of your neck!). I still took on the anxiety story and did something against it. It helped me in many ways but not with post-viral syndrome. It's real and it sucks but it's not being taken seriously at all. I am afraid, some COVID survivors are in for a new life which is different in just the right (but minor) ways to drive you insane. Body just doesn't feel the same as before.
  - rtp 6y ago
    It's amazing how people think a virus that lives latently in B cells and epithelial cells, and is strongly associated with various forms of cancer among a big helping of autoimmune disorders, is incapable of causing post-viral syndromes. No, it must be anxiety, of course! EDIT: Just because a disease makes you frustrated because you can't really do anything about it except empathize and listen, doesn't mean you can just slap the anxiety band-aid on it and call it a day.
    - neuronic 6y ago
      Correct, I don't expect doctors to cure me. I expect them to acknowledge that EBV could play a part here. But nope, just anxiety.
  - throwaway1092 6y ago
    > But things like autoimmune issues, persistent 15-year brain fog (I'd rather call it frosted glass layer) which randomly clears once a month to remind me how nice it is to be able to think straight I've been experiencing something similar for the past 5 years: brain fog (frosted glass is a much better way of putting it.) and some short term memory issues. The doctors put me through a battery of tests to find...that they could find no reason for my ailment. Curious to know what if anything has helped you the most. The 'randomly clearing' brain fog for a day happens to me maybe once every 3 months and it's both a blessing and a curse.
    - jokab 6y ago
      Sorry to hear this. I cured mine with a CPAP machine. I had to be tested with apnea twice bc the first one came out ok but i wasnt convinced. In any case, i hope you feel better
      - throwaway1092 6y ago
        Thanks - already had/have a CPAP machine, so unfortunately that's not it.
  - 6y ago
ghufran_syed 6y ago
Not sure why you’re getting downvoted - here’s a page about post-intensive care syndrome, on the website of the society for critical care medicine, that’s concordant with what you said: https://www.sccm.org/MyICUCare/THRIVE/Post-intensive-Care-Syndrome https://www.sccm.org/MyICUCare/THRIVE/Post-intensive-Care-Sy...
- noja 6y ago
  > Not sure why you’re getting downvoted I think he overlooked that the people were hospitalized and on ventilators because they had covid.
  - xd 6y ago
    But it's still an effect of the treatment. If you perform a study on people whom have been ill you're going to get results that show all the symptoms of illness.. the study could have been done with any illness and likely show cognitive decline.
    - shultays 6y ago
      symptoms of illness is the illness itself. Ignoring these symptoms of covid or results of the treatment is saying something like "bullets don't kill people, it ruptures blood vessels and you die due to loss of blood"
      - srtjstjsj 6y ago
        You misunderstand the ambiguous wording. If you study only includes people with an illness, the illness itself is a confounder. The point is that if you have a non-ICU covid case, this research is unlikely to apply.
        jrumbut 6y ago
        It feels like we didn't read the same article, they break down numbers for people on ventilators but also hospitalized, non-ventilator patients all the way down to those who received no particular care. The findings were concerning to anyone who had it, they also mention cases where the cognitive deficit was the first reported symptom.
xd 6y ago
Also, I had a brief look over the paper but couldn't find anything to control for isolation since lockdown .. surely this would of had an effect on peoples cognition. On a side note, maybe it's just me but I keep seeing comments that don't follow a "politically" accepted view point, being down vote like yours.
- w_t_payne 6y ago
  Maybe it's because this whole situation has been ridiculously politicized, to the point where it's difficult to have a rational fact-based discussion.
  - hejja 6y ago
    ...about anything. not just covid.
    - EForEndeavour 6y ago
      That's exactly what someone with your political beliefs would say!!
- deleted 6y ago
  [deleted]
- jmull 6y ago
  I don't know why people downvote things, but in this case I would hope it's because the previous comment was pretty superficial. Whether the covid causes cognitive decline through causing the use of a ventilator, sedatives, and immobilization or through some other mechanism still means it causes cognitive decline. So there's a basic logic flaw. Also, quite a large number of people have been put on ventilators due to covid-19, not "almost nobody". That's just an incorrect assertion. You'd like to attribute the downvoting to politics, but given the quality issues, I think that's a hard claim to support.
- api 6y ago
  If isolation with a net connection for a few months dropped multiple IQ points, then all the shut-ins who do nothing but hang around on the Internet all day would be losing multiple tens of IQ points a year and would be functionally disabled by now.
regularfry 6y ago
The error bars overlap with the "hospitalised without ventilation" group. There's probably something else going on, and the authors do call out the known cognitive effects of hypoxia.
nradov 6y ago
There is some evidence that anesthetics can cause cognitive impairment. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443620/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443620/
- kube-system 6y ago
  I was under the impression, at least as it pertained to the elderly, that GA is commonly known to be a significant risk.
  - nradov 6y ago
    Any type of long hospital stay frequently causes delirium among the elderly. GA makes it worse. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065676/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065676/
simonh 6y ago
Most of the impact seems to occur even without serious symptoms: >bio-positive cases who reported being ill with no breathing difficulties showed a 0.32SD magnitude cognitive deficit. My wife's hospital was full to the corridors with 'almost nobody's.
paradox242 6y ago
As other have already commented, they have already considered your theory in their analysis: "Consequently, the observation of post-infection deficits in the subgroup who were put on a ventilator was not surprising. Conversely, the deficits in cases who were not put on a ventilator, particularly those who remained at home, was unexpected." This effect on those hospitalized is not the primary thrust of their paper. Instead it was the observed effects on those who were not hospitalized or had mild to no respiratory symptoms. They raise many possibilities about why this may be the case and only assert that this effect at least proceeds into the recovery phase. I did not read any claims about this being permanent, broadly speaking.
biolurker1 6y ago
As many previous comments said, the article includes mild disease

st1x7 6y ago

Reduction equivalent to the cognitive decline of aging 10 years and larger than the cognitive decline of suffering a stroke? Sounds pretty substantial to me.

minitech 6y ago
“not insubstantial” :)
- dempseye 6y ago
  This is a very English way of expressing oneself.
  - taneq 6y ago
    Well it's not unEnglish.
    - metalliqaz 6y ago
      "inflammable means flammable?"
      - solarkraft 6y ago
        "all but"
  - deleted 6y ago
    [deleted]
  - julianlam 6y ago
    I also used to find this disturbing, but the way I have explained this to myself is -- Insignificant < 25% Not insignificant 25-50% Not significant 50-75% Significant > 75% Of course for each individual situation the numbers vary, and I use them simply to demonstrate that it's a matter of degrees, and not as binary as you may expect a typical "not" to be. It is the only double negative I have come to find useful.

sokoloff 6y ago

It’s equally as surprising to me the suggestion that the average decline in IQ from a stroke would be only 6 points or so.

srtjstjsj 6y ago
It's an average. Strokes can be very small and localized.
treeman79 6y ago
Varies a lot. I get a lot of minor strokes if I skip blood thinners for a week or so. At peak I’m a highly effective programmer. If I’ve had one recently, a “for loop” is a challenging concept. After a few days to weeks I’ll be back to near normal. Some symptoms last longer. Highly active Factor 5 Leiden, so I clot like crazy.
- hderms 6y ago
  That sounds incredibly difficult. You must be a very strong and intelligent person.
  - treeman79 6y ago
    Thank you, yes beyond challenging. Mostly at this point because I work technical jobs and have no idea how to step down to lower role where periodic reduced intelligence is less of an issue.
gen220 6y ago
The impact of a stroke varies a lot with the kind of stroke, and the proximity of quality treatment. An awful stroke speedily treated by top doctors has the chance of imparting basically no change to cognitive function. Of the same token, not-the-worst strokes with mediocre care can ruin one's capacity to work. It's a really complicated medical event, with high variance in outcome. Strokes suck.

mrfusion 6y ago

I’d be curious to see this compared to people hospitalized on ventilators for other diseases. You’re not in good shape at that point and I’d expect all kinds of problems.

usrusr 6y ago
Does it matter though? The answer certainly depends on the context of the question: do we just want to assess the risks more precisely than the dead/alive boolean? No, it doesn't matter. Do we want to increase humanity's knowledge about how the virus affects our bodies? Yes, absolutely, if it's worse than standard damage of respirator episodes we'll want to know the "mechanisms" that we causing that extra damage.
- mrfusion 6y ago
  If we’re being asked to give up our way of life, keep children out of school, damage mental health, give up essential freedoms. Then yes, I’d like to see it compared to existing diseases we’ve been living normally alongside for centuries!
ineedasername 6y ago
It's not (just) a matter of whether or not Covid is worse than other serious illnesses. It's that whatever existed already, Covid adds on top of that. So if there were X people that experienced significant health problems before, now there are X + Covid.

cltby 6y ago

I'm certainly not accusing you of this personally, but it's curious how selectively IQ is accepted/denied on this site. It's real enough for the purposes of covid policy, lead abatement, or whatever other fashionable environmental intervention. In just about every other case, flat out denialism.

salicideblock 6y ago
The general concern with IQ when used for policymaking, or with standardized "intelligence" tests in general, is that they can fail to account for environmental or cultural factors across individuals or populations. In both cases of covid and lead effects, the effect can be measured on the same population, and/or controlled for proxies of those factors (see "when controlling for age, gender, education level, income, racial-ethnic group and pre-existing medical disorders" in the article. So the general concern with the metric can be excluded.
- cltby 6y ago
  Psychologists are just as adept at "controlling for age, gender, education level, income, racial-ethnic group." The validity of IQ was first established using within-group comparisons.
bitdizzy 6y ago
IQ is somewhat effective as a diagnostic tool for significant impairment and not much else. Your examples of where it is not contentious are exactly cases where you must measure impairments. Do you want to list some example contexts where you witness "flat out denialism"? In any case there is an important point: The variance of measured IQ for the same individual over time is very high. It's hard to extract a signal for that unless there's a severe effect being measured.
- cltby 6y ago
  > IQ is somewhat effective as a diagnostic tool for significant impairment and not much else This places exactly zero constraints on the utility of IQ tests. Instead of asking why group A scores higher than group B, I can simply ask why group B is impaired relative to group A. Apparently that should be enough to convince you of the validity of the comparison. > The variance of measured IQ for the same individual over time is very high. The test-retest correlations of IQ batteries are typically in the 0.8-0.9 range. For example, the Wechsler test [1]. This makes IQ probably the single most reliable measure in the social sciences. Perhaps you're referring to the Wilson effect, but that's not at issue here. [1] https://images.pearsonclinical.com/images/pdf/wisciv/WISCIVTechReport2.pdf https://images.pearsonclinical.com/images/pdf/wisciv/WISCIVT...