Structural changes in the brain after Covid 19 infection: appear to occur regardless of illness severity

[SchnitzelVonCrummsTum]

Brain imaging before and after Covid 19 infection.

Caveat: this is a pre-print

www.medrxiv.org/content/10.1101/2021.06.11.21258690v1.full

Sharing for information for anyone interested mainly - a well-designed study. Structural differences found in cases regardless of severity. Functional implications not yet known.

"Here, we studied the effects of the disease in the brain using multimodal data from 782 participants from the UK Biobank COVID-19 re-imaging study, with 394 participants having tested positive for SARS-CoV-2 infection between their two scans. We used structural and functional brain scans from before and after infection, to compare longitudinal brain changes between these 394 COVID-19 patients and 388 controls who were matched for age, sex, ethnicity and interval between scans. We identified significant effects of COVID-19 in the brain with a loss of grey matter in the left parahippocampal gyrus, the left lateral orbitofrontal cortex and the left insula. When looking over the entire cortical surface, these results extended to the anterior cingulate cortex, supramarginal gyrus and temporal pole. We further compared COVID-19 patients who had been hospitalised (n=15) with those who had not (n=379), and while results were not significant, we found comparatively similar findings to the COVID-19 vs control group comparison, with, in addition, a greater loss of grey matter in the cingulate cortex, central nucleus of the amygdala and hippocampal cornu ammonis (all |Z|>3). Our findings thus consistently relate to loss of grey matter in limbic cortical areas directly linked to the primary olfactory and gustatory system. "

Thank you for sharing this.

So even in “mild” Covid cases there was some loss of grey matter? IIRC grey matter cannot be regenerated - loss is permanent.

It’s very concerning that since Covid can be caught multiple times, then each subsequent infection could result in further loss of grey matter.

And if vaccines do not stop us from catching the virus (although they do help with reducing transmission and severity) then what? Perhaps I have put two and two together and made five (not a scientist).

Yes, what does it actually mean?

Does it mean clear cognitive impairment?

I wasn’t sure what grey matter does in the brain, so I had a Google and found this article which sums up the study:

m.businesstoday.in/story/new-uk-study-shows-substantial-loss-of-grey-matter-in-brains-of-recovered-covid-19-patients/1/441964.html

Basically it damages the part of the brain which controls sense of taste and smell, memory, cognitive ability.

Possibly loss of smell and taste. Olfactory and gustatory systems are affected.
Loss of grey matter in theses regions seems to be the problem but the brain is quite good at rerouting nerves signals when areas are damaged so may need to retrain these areas.

"what does it mean?"

The study authors are very careful to point out this shows association, not causation, which mean although there will be lots of scary headlines from MSM, they have not found definitive evidence that COVID-19 infection causes damage to the brain.

This is good thread:
twitter.com/Neuro_Skeptic/status/1406694386419879937

basically, the authors have found small differences in brain structure before and after COVID infection, compared to matched controls. Whether they were caused by infection itself, rather than other factors, remains to be confirmed in follow up studies.

"As this study is observational (as opposed to a randomised, controlled, interventional study), one cannot make claims of disease causality with absolute certainty, but interpretational ambiguities are greatly reduced compared with post hoc cross-sectional studies."

@LimitIsUp

Does it mean clear cognitive impairment?

no they definitely aren't claiming that - differences in brain structure (especially such small differences) do not automatically mean damage or cognitive impairment

they have also done cognitive testing in UK Biobank, so I would expect a second paper to be published by the same group on this imminently

but again, as the authors have stated, this study design does not allow you to definitively say any differences were caused by COVID infection

@Inthemane

Thank you for sharing this.

So even in “mild” Covid cases there was some loss of grey matter? IIRC grey matter cannot be regenerated - loss is permanent.

It’s very concerning that since Covid can be caught multiple times, then each subsequent infection could result in further loss of grey matter.

And if vaccines do not stop us from catching the virus (although they do help with reducing transmission and severity) then what? Perhaps I have put two and two together and made five (not a scientist).

Grey matter volume can actually increase - lots of studies look at specific interventions like CBT and whether these increase brain volume (generally via cortical thickness). The brain is lot more plastic than people first thought.

And if vaccines do not stop us from catching the virus (although they do help with reducing transmission and severity) then what?

Once 80-90% are fully vaccinated, we get true herd immunity. Limited chance for the virus to spread or mutate.

Biden's calls for a temporary vaccine patent waiver would massively help to speed things up, in getting the world vaccinated. I hope his talks with the drugs companies are successful.

I wonder if the lack of taste/smell caused the reduction of grey matter in that area as it had less stimulation or whether the reduction in grey matter caused the loss of smell.

Plastic brains and all that.

So even in “mild” Covid cases there was some loss of grey matter? IIRC grey matter cannot be regenerated - loss is permanent.

But grey matter does come back.

The same thing is observed before / during pregnancy / post childbirth, i.e baby brain.

Someone shared this on another thread earlier as 'concerning for children'. But A) the study was done on over 45s and B) a quick google of the scientific terms (I'm not a scientist) showed this is loss of smell and taste (which we know about) and well... something that could easily be described as brain fog (which we all know about).

Not saying it is brain fog... just saying you could jump to either conclusion. And since there is already widely documented evidence (and lived experience) of brain fog after cold, flu, pneumonia etc, why would you jump to brain damage?

See I knew there had to be a logical explanation for why the Tories were doing so well in the polls.

Have there been any similar studies in relation to other viruses? I'm thinking that long Covid has lots of similarities to post viral syndrome so it's probably not all that different or more marked.

But grey matter does come back

Winched Grey Matter doesn't regenerate, except in a few key areas - and even then, rarely. White matter does regenerate happily. Trust me, I know this as a veteran of a disease that damages the brain tissue permanently.

@TheClaws

But grey matter does come back

Winched Grey Matter doesn't regenerate, except in a few key areas - and even then, rarely. White matter does regenerate happily. Trust me, I know this as a veteran of a disease that damages the brain tissue permanently.

sorry to hear you've struggled with this @TheClaws, I hope you're doing ok

I think in terms of the paper there's a difference when comparing damage caused by something like a catastrophic stroke or like a neurodegenerative disease, and the very slight differences (by a couple of standard deviations) they see in volume/thickness measures reported between groups here. Fortunately grey matter volume/thickness is quite fluid, and can increase after injury, but is not always the case. I've got a couple of examples (sorry am a bit of a nerd on this area )

grey matter increases after stroke aids motor recovery
www.ncbi.nlm.nih.gov/pmc/articles/PMC5369868/

grey matter can increase in response to various interventions like CBT

www.ncbi.nlm.nih.gov/pmc/articles/PMC3874446/#:~:text=An%2011%2Dweek%20CBT%20intervention,associated%20with%20reduced%20pain%20catastrophizing.

grey matter increases and decrease can be seen during the menstrual cycle
journals.plos.org/plosone/article?id=10.1371/journal.pone.0014655

so if differences were found to be causal in the UK Biobank study, it does not automatically mean they are permanent

It means loss of smell and taste. As others have said these can be rerouted.

Interesting and frightening.

I am 51. I have small vessel disease and cerebral and cerebellar degeneration, that was diagnosed a couple of years ago. Neurologist said I should have a good 20 years in me! Not sure if he was just trying to reassure me or not.

I had Covid at New Year, main symptoms were severe headache, tinnitus, dullened hearing and complete loss of smell and taste, which are back a bit but not completely.

Scary, the virus that keeps on giving.

I think in terms of the paper there's a difference when comparing damage caused by something like a catastrophic stroke or like a neurodegenerative disease, and the very slight differences (by a couple of standard deviations) they see in volume/thickness measures reported between groups here.

Than you for your good wishes olly, and I assumed the above - I see it somewhat like a very temporary inflammatory response.

I think i had covid last apr. It would feel like your brain forgot to breath. That went on for several months. About 6m in i started to get sleep issues and numb hands (even though breathing was better) and muscle twitching. It seems like my brain stopped the automatic rolling you do in sleep.
A lot of people on lc groups have brain fog.
My already poor short term memory seems worse and things like actors names or spellings are much worse - however it is often things i have used in a while.

I feel like I've lost grey matter just from a tedious lockdown existence and months of 80% of my interaction being about Minecraft/ Roblox/ Among Us, and umpteen hours a day having shouty gamers like Preston Playz on the TV. No actual covid involved.
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