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Harlan Krumholz
@hmkyale
@uk_biobank @medrxivpreprint There are caveats to the study… and the changes associated with COVID are based on imaging… and there are many questions remaining. But this study is providing very useful information. And the @uk_biobank study is on-going.
2021-06-18 07:37:30
Harlan Krumholz
@hmkyale
@uk_biobank @medrxivpreprint And this was the most striking (concerning) figure to me...Histograms of group comparison Z statistics of longitudinal change in cortical thickness. The longitudinal effects were localized, but the effects could be seen across the entire cortical surface. Yikes. pic.twitter.com/wT0JEOQZ3v
2021-06-18 07:43:24
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Harlan Krumholz
@hmkyale
@uk_biobank @medrxivpreprint And it is perplexing that the strongest effects of COVID seem to have been in the left brain hemisphere… though this finding needs further validation. Is it because it is more involved in the ‘emotional aspect of olfactory memory’, as the authors opine?
2021-06-18 07:45:17
Harlan Krumholz
@hmkyale
@uk_biobank @medrxivpreprint And for a dark implication of the study… the authors question whether the physical proximity of the brain loss to the hippocampus might have implications for future risk of Alzheimer’s or other forms of dementia. This should give even more fuel to prevention efforts. #LongCovid
2021-06-18 07:47:02
Harlan Krumholz
@hmkyale
@uk_biobank @medrxivpreprint This UK study also indicates to me the importance of ever greater investment into science of COVID & #longCOVID as we seek to mitigate its consequences. Is any of it reversible? By what means? Meanwhile, folks, get your vaccinations. It's not just about averting hospitalization.
2021-06-18 07:49:08
gene
@momotar37156452
（スレッド） 「COVID-19関連の無嗅覚症は、ヒトの嗅上皮におけるウイルスの持続性と炎症、およびハムスターにおける脳感染に関連」 twitter.com/dgurdasani1/st…
2021-06-22 08:01:34
Dr. Deepti Gurdasani
@dgurdasani1
More & more evidence accruing that SARS-CoV-2 causes significant persistent effects on the brain. We now have multiple strands supporting this- -long-term symptoms-brain fog, memory loss -higher risk of stroke/neuro diseases -structural brain changes -virus persistence in brain🧵
2021-06-21 06:32:00
Dr. Deepti Gurdasani
@dgurdasani1
More & more evidence accruing that SARS-CoV-2 causes significant persistent effects on the brain. We now have multiple strands supporting this- -long-term symptoms-brain fog, memory loss -higher risk of stroke/neuro diseases -structural brain changes -virus persistence in brain🧵
2021-06-21 06:32:00
Dr. Deepti Gurdasani
@dgurdasani1
We know that SARS-CoV-2 is neuro-invasive. This means that it enters the brain- we think this is through the olfactory nerve (the nerve that helps us smell) through the nose. This has been shown in mice, hamsters and directly in humans in autopsies. nature.com/articles/s4159… pic.twitter.com/kB76MsfWlH
2021-06-21 06:32:02
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Dr. Deepti Gurdasani
@dgurdasani1
Replicating SARS-CoV-2 has also been shown to persist in neuro-epithelium (olfactory nerves in the nose) for up to 6 months among people who have recurrent or persistent loss of smell. stm.sciencemag.org/content/13/596…
2021-06-21 06:32:03
Dr. Deepti Gurdasani
@dgurdasani1
Neurological symptoms are significant among people post-COVID, & they persist for long periods of time, even after other symptoms recover. ONS data shows that problems with concentration, memory, brain fog, loss of smell/taste are common persistent symptoms after infection pic.twitter.com/1BmDVctsdo
2021-06-21 06:32:04
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Dr. Deepti Gurdasani
@dgurdasani1
Symptom based surveys have consistently shown that neurological symptoms are more likely to arise later, and persist over time, and symptom clusters that have neurological symptoms generally also correlate with poorer day to day functioning. pic.twitter.com/Oyj7GbcWLE
2021-06-21 06:32:05
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Dr. Deepti Gurdasani
@dgurdasani1
A @TheLancetPsych study showed that neurological & psychiatric diagnosis were very common at 6 months after COVID-19, and the risk for psychiatric disorders, strokes, dementia, muscle disorders was significantly higher, even in those not hospitalised. twitter.com/dgurdasani1/st…
2021-06-21 06:32:06
Dr. Deepti Gurdasani
@dgurdasani1
Important study out from @TheLancetPsych on neurological & psychiatric manifestations across 236,379 people with 6 months follow up after COVID-19 in the US- examined using electronic health records. What did it find? thelancet.com/journals/lanps…
2021-04-07 18:02:58
Dr. Deepti Gurdasani
@dgurdasani1
There have been earlier studies that have looked at cognitive decline following hospitalisation with COVID-19 suggesting significant reduction after hospitalisation. These studies have been limited by not having measurements pre-COVID-19 to establish that this was the cause.
2021-06-21 06:32:07
Dr. Deepti Gurdasani
@dgurdasani1
This is addressed now in a study within UK biobank. This is a cohort of generally healthy people who have had many measurements done as part of the study. ~40,000 people have had brain imaging done for research purposes before the COVID-19 pandemic.
2021-06-21 06:32:07
Dr. Deepti Gurdasani
@dgurdasani1
Of the people who have had their second MRI brain scan in the Biobank study, some of them developed COVID-19 before the second scan. We can compare brain changes between those infected vs not infected by comparing the change in brain structure between the two scans.
2021-06-21 06:32:07
Dr. Deepti Gurdasani
@dgurdasani1
394 people who were COVID-19 positive (only 15 of these were hospitalised) were imaged after COVID-19 was diagnosed. These were compared with 388 controls (not diagnosed with COVID-19). Both groups had MRI scans done before the pandemic at baseline.
2021-06-21 06:32:08
Dr. Deepti Gurdasani
@dgurdasani1
They were compared for volume and thickness in certain areas of the brain. Cases & controls were matched for age, sex, ethnicity & the time between the baseline and repeat MRI scan to ensure any difference in change in brain structure between the two groups was not down to these.
2021-06-21 06:32:08
Dr. Deepti Gurdasani
@dgurdasani1
The groups were well matched. Age was between 47-80 (mean age ~59). Similar blood pressure, prevalence of diabetes and BMI. As mentioned, most of the COVID group was people who were infected & tested in the community with non-severe COVID-19. pic.twitter.com/wVFHdTGSBV
2021-06-21 06:32:10
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Dr. Deepti Gurdasani
@dgurdasani1
Most of the patients had been diagnosed Oct 2020 or after, and the duration between infection and scan varied accordingly. Mean duration was 4.5 months post COVID-19 pic.twitter.com/dGd88jZffg
2021-06-21 06:32:11
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Dr. Deepti Gurdasani
@dgurdasani1
The study found significant reduction in grey matter in certain parts of the brain- especially those associated with smell, and memory. Of note- these are changes in a population of people who mostly had mild COVID symptoms - *greater* reduction from baseline in those with COVID pic.twitter.com/xTnfiAM2Sc
2021-06-21 06:32:12
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Dr. Deepti Gurdasani
@dgurdasani1
While correlation isn't causation, the fact that these people were imaged at baseline before COVID-19 - allowing to compare to a group not infected with COVID-19 to look at difference in decline in grey matter after COVID compared to those who weren't infected makes it strong.
2021-06-21 06:32:13
Dr. Deepti Gurdasani
@dgurdasani1
Remember, these groups were also the same age, had the same interval between scans, and many similar characteristics, making it unlikely this decline is down to something other than COVID-19
2021-06-21 06:32:13
Dr. Deepti Gurdasani
@dgurdasani1
This is very concerning- we are seeing evidence of significant changes in the brain even among people with relatively mild COVID-19. This study was in 46-80 yr olds, and many would've been healthy. We urgently need to understand the impact of COVID-19 in younger age groups too.
2021-06-21 06:32:14
Dr. Deepti Gurdasani
@dgurdasani1
This isn't just one study that suggests a link between SARS-CoV-2 and neurodegenerative disease. There have been several care reports of early-onset parkinsonism after SARS-CoV-2 infection, highlighting possible links with neuro-degenerative disease. thelancet.com/journals/laneu…
2021-06-21 06:32:14
Dr. Deepti Gurdasani
@dgurdasani1
Does this happen with other viruses? Yes, many viruses invade and affect the brain: herpes viruses, Zika virus, measles, polio and of course, Spanish flu (encephalitis lethargica as immortalised in Awakenings). Other coronaviruses are known to invade the brain too.
2021-06-21 06:32:15