5 ms·

There's a UK brain imaging study - small, due to the fact that one required the "lucky" confluence of having participated in the study before the COVID-19 epide

There's a UK brain imaging study - small, due to the fact that one required the "lucky" confluence of having participated in the study before the COVID-19 epidemic, and having gotten COVID - showing the kind of longitudinal effects you are asking for. Alarmingly, it shows shrinkage of various brain structures even among the mildly ill. Note this is a not-yet-peer-reviewed preprint. https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v2 https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v... IMO, while I'm not inclined to take either study at face value immediately, I think a serious person should be equally reluctant to join the "it's just a flu" camp either.

saddlerustle 5y ago
Apart from the effect size in that study being pretty low, theres the obvious sampling problem in that sort of people regularly having their brain imaged are not normal!
- glangdale 5y ago
  I'm not clear on what level of "pretty low" I'd have to see before being reassured here. I guess it's HN, where I'm the only dummy who doesn't know what acceptable changes in everyday metrics like "Parahippocampal gyrus thickness" and "Lateral orbitofrontal cortex volume" are. Your second remark is also peculiar: the "obvious sampling problem" to which you allude is either (1) a subtler-than-expected-point about the UK Biobank's program (designed to be a mass participation program to observe longitudinal effects in previous healthy or as yet undiagnosed people) or (2) evidence you are just making stuff up.
- Aeolun 5y ago
  I dunno, I just have anxiety and the docs only feel safe ruling certain stuff out after either a CT or MRI. If I ever contract COVID I can look back through multiple years of history.
yourenotsmart 5y ago
> I think a serious person should be equally reluctant to join the "it's just a flu" camp either. The long-term effects of flu are not studied that well, by the way. On the basis we're used to it from before such studies were possible. None of those symptoms we hear about, getting our breath, unable to smell, brain fog etc., none of them are new. And they imply internal damage that lasts.
subroutine 5y ago
Looking at the scatter plot from their most statistically significant finding (parahippocampal gray matter change), the effect size is tiny, and the variance is large. Nearly half the case participants had more gray matter after getting COVID. https://i.ibb.co/5YcxJHH/EDB20654-900-A-427-C-8063-B5-FA667-A0-D79.jpg https://i.ibb.co/5YcxJHH/EDB20654-900-A-427-C-8063-B5-FA667-...
- jvanderbot 5y ago
  That's not what I see in that plot. I see a distribution shift, with zero linkage between before and after cases that would suggest "Half had more gray matter" Figure 2 is the one you want https://els-jbs-prod-cdn.jbs.elsevierhealth.com/cms/attachment/e84bb276-f386-405b-bfc5-37d1cbcf1fef/gr2.jpg https://els-jbs-prod-cdn.jbs.elsevierhealth.com/cms/attachme... Which does show effect increasing with severity of the case. I've seen plots like that before in similar articles. See also table 2.
- glangdale 5y ago
  As I've stated elsewhere, apparently everyone on HN understands what acceptable levels of "parahippocampal gray matter change" might be, which is reassuring. "Nearly half the case participants had more gray matter after getting COVID" - as did the controls. It's almost like there's variability in the readings. If only someone would invent a subspeciality of mathematics about how to interpret noisy data and attempt to draw conclusions about the results. I'm not totally sold on this study either, mind you. I'm just amazed at how many people are rushing to judgement in the other direction - the whole "just a flu" conclusion is wildly premature.
  - subroutine 5y ago
    > It's almost like there's variability in the readings. If only someone would invent a subspeciality of mathematics about how to interpret noisy data and attempt to draw conclusions about the results. Yes, I mention the high variance. And indeed there are standard ways to interpret the effect size magnitude, given noisy data. The authors chose not to report Cohen's d. They do provide an r value (.16), which we can use to compute the the coefficient of determination. Since you are an advocate for reliance on traditional statistical interpretations, you should appreciate the meaning of r^2=.025 Furthermore the authors report a P=.01. They bootstrap this P, presumably because alpha significance level after multiple comparison adjustment renders cutoff well below .01. They also claim no a priori hypothesis wrt. gray matter increase or decrease. A 2-tailed alpha is typically shifted from p<.05 to p<.01 which their measured P value does not surpass. Nevertheless they claim statistical significance. Finally, after normalization, there is roughly an equal chance any given person will have more or less gray matter after getting covid - this doesn't require one to glean the importance of each ounce of gray matter to understand the effect size is small. I contend there is good reason this study has not yet passed peer review, if it ever will.
NoblePublius 5y ago
we are up to 2 billion+ covid infections globally, so if 1% have Long Haul…where the hell are they?
- mmmmmbop 5y ago
  Where did you read that number (2B+ Covid infections)?
  - NoblePublius 5y ago
    Assume covid tests find about 1 out of 5 total infections
- amcoastal 5y ago
  In most countries they are probably dead.
- renonce 5y ago
  It's 200 million or 0.2 billion
  - caseysoftware 5y ago
    According to the CDC, the US has had an (estimated) 100M+ infections as of mid-April[0] and Europe had 50M+ as of last week.[1] I don't know the appropriate way to extrapolate out but we're well past 200M globally. 0: https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burden.html https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd... 1: https://graphics.reuters.com/world-coronavirus-tracker-and-maps/regions/europe/ https://graphics.reuters.com/world-coronavirus-tracker-and-m...
- renaudg 5y ago
  A large number of these infections are simply too recent for "long haul" Covid to have settled in. There's also not a globally accepted definition of the syndrome yet, so it won't show up in stats. If you go by "still experiencing at least one symptom after 3 months", it's closer to 10-20% than 1% : https://twitter.com/Dr2NisreenAlwan/status/1377549257570316290 https://twitter.com/Dr2NisreenAlwan/status/13775492575703162... Another study found that around a third of these 10-20% consider it debilitating (significantly affects their daily lives)

saddlerustle 5y ago

Apart from the effect size in that study being pretty low, theres the obvious sampling problem in that sort of people regularly having their brain imaged are not normal!

glangdale 5y ago
I'm not clear on what level of "pretty low" I'd have to see before being reassured here. I guess it's HN, where I'm the only dummy who doesn't know what acceptable changes in everyday metrics like "Parahippocampal gyrus thickness" and "Lateral orbitofrontal cortex volume" are. Your second remark is also peculiar: the "obvious sampling problem" to which you allude is either (1) a subtler-than-expected-point about the UK Biobank's program (designed to be a mass participation program to observe longitudinal effects in previous healthy or as yet undiagnosed people) or (2) evidence you are just making stuff up.
Aeolun 5y ago
I dunno, I just have anxiety and the docs only feel safe ruling certain stuff out after either a CT or MRI. If I ever contract COVID I can look back through multiple years of history.

yourenotsmart 5y ago

> I think a serious person should be equally reluctant to join the "it's just a flu" camp either. The long-term effects of flu are not studied that well, by the way. On the basis we're used to it from before such studies were possible. None of those symptoms we hear about, getting our breath, unable to smell, brain fog etc., none of them are new. And they imply internal damage that lasts.

subroutine 5y ago

Looking at the scatter plot from their most statistically significant finding (parahippocampal gray matter change), the effect size is tiny, and the variance is large. Nearly half the case participants had more gray matter after getting COVID. https://i.ibb.co/5YcxJHH/EDB20654-900-A-427-C-8063-B5-FA667-A0-D79.jpg https://i.ibb.co/5YcxJHH/EDB20654-900-A-427-C-8063-B5-FA667-...

jvanderbot 5y ago
That's not what I see in that plot. I see a distribution shift, with zero linkage between before and after cases that would suggest "Half had more gray matter" Figure 2 is the one you want https://els-jbs-prod-cdn.jbs.elsevierhealth.com/cms/attachment/e84bb276-f386-405b-bfc5-37d1cbcf1fef/gr2.jpg https://els-jbs-prod-cdn.jbs.elsevierhealth.com/cms/attachme... Which does show effect increasing with severity of the case. I've seen plots like that before in similar articles. See also table 2.
glangdale 5y ago
As I've stated elsewhere, apparently everyone on HN understands what acceptable levels of "parahippocampal gray matter change" might be, which is reassuring. "Nearly half the case participants had more gray matter after getting COVID" - as did the controls. It's almost like there's variability in the readings. If only someone would invent a subspeciality of mathematics about how to interpret noisy data and attempt to draw conclusions about the results. I'm not totally sold on this study either, mind you. I'm just amazed at how many people are rushing to judgement in the other direction - the whole "just a flu" conclusion is wildly premature.
- subroutine 5y ago
  > It's almost like there's variability in the readings. If only someone would invent a subspeciality of mathematics about how to interpret noisy data and attempt to draw conclusions about the results. Yes, I mention the high variance. And indeed there are standard ways to interpret the effect size magnitude, given noisy data. The authors chose not to report Cohen's d. They do provide an r value (.16), which we can use to compute the the coefficient of determination. Since you are an advocate for reliance on traditional statistical interpretations, you should appreciate the meaning of r^2=.025 Furthermore the authors report a P=.01. They bootstrap this P, presumably because alpha significance level after multiple comparison adjustment renders cutoff well below .01. They also claim no a priori hypothesis wrt. gray matter increase or decrease. A 2-tailed alpha is typically shifted from p<.05 to p<.01 which their measured P value does not surpass. Nevertheless they claim statistical significance. Finally, after normalization, there is roughly an equal chance any given person will have more or less gray matter after getting covid - this doesn't require one to glean the importance of each ounce of gray matter to understand the effect size is small. I contend there is good reason this study has not yet passed peer review, if it ever will.

NoblePublius 5y ago

we are up to 2 billion+ covid infections globally, so if 1% have Long Haul…where the hell are they?

mmmmmbop 5y ago
Where did you read that number (2B+ Covid infections)?
- NoblePublius 5y ago
  Assume covid tests find about 1 out of 5 total infections
amcoastal 5y ago
In most countries they are probably dead.
renonce 5y ago
It's 200 million or 0.2 billion
- caseysoftware 5y ago
  According to the CDC, the US has had an (estimated) 100M+ infections as of mid-April[0] and Europe had 50M+ as of last week.[1] I don't know the appropriate way to extrapolate out but we're well past 200M globally. 0: https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burden.html https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd... 1: https://graphics.reuters.com/world-coronavirus-tracker-and-maps/regions/europe/ https://graphics.reuters.com/world-coronavirus-tracker-and-m...
renaudg 5y ago
A large number of these infections are simply too recent for "long haul" Covid to have settled in. There's also not a globally accepted definition of the syndrome yet, so it won't show up in stats. If you go by "still experiencing at least one symptom after 3 months", it's closer to 10-20% than 1% : https://twitter.com/Dr2NisreenAlwan/status/1377549257570316290 https://twitter.com/Dr2NisreenAlwan/status/13775492575703162... Another study found that around a third of these 10-20% consider it debilitating (significantly affects their daily lives)