Cognitive reserve moderates the effect of COVID-19 on cognition: A systematic review and meta-analysis of individual participant data, 2025, Foreman+

SNT Gatchaman

SNT Gatchaman

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Cognitive reserve moderates the effect of COVID-19 on cognition: A systematic review and meta-analysis of individual participant data
Foreman; Child; Saywell; Collins-Praino; Baetu

Elucidating the factors that mitigate the effects of COVID-19 on cognitive function offers important insights for public health policy and intervention. This systematic review and individual participant data (IPD) meta-analysis assesses cognitive reserve (CR) as a potential moderator of post-COVID-19 cognitive dysfunction (PCCD).

Under PRISMA-IPD guidelines, data searches were conducted via PubMed, PsycINFO, Scopus, and Embase, up to January 2023. Eligible studies included at least one cognitive assessment, CR proxy, and disease severity indicator. Of 5,604 studies, 87 were eligible (10,950 COVID-19 cases; 78,305 controls), and IPD was obtained for 29 datasets (3,919 COVID-19 cases; 8,267 controls).

Three-level random-effects meta-analyses indicated that CR had a moderate positive association (rsp =.29), and COVID-19 severity had a small negative association (rsp = -.07) with cognitive outcomes. These effects were moderated by a significant within-study interaction. Cognitive deficits following COVID-19 were 33% smaller among high CR individuals, and 33% greater among low CR individuals, relative to those with average CR.

Population-based initiatives promoting reserve-building behaviors may alleviate the PCCD-related public health burden.

HIGHLIGHTS
• Cognitive reserve moderates the effect of COVID-19 severity on cognition.

• This moderation effect can be found at both the within- and between-study level.

• High cognitive reserve is a protective factor which reduces the impact of COVID-19 on cognition.

• The effect is present across the whole COVID-19 spectrum, including in mild cases.

• Population-based public health initiatives should promote reserve-building behaviors.

Link (Neuroscience & Biobehavioral Reviews)
 
First, 87 studies of cognitive dysfunction following Covid-19, before January 2023? That seems a lot.

Abstract said:
Population-based public health initiatives should promote reserve-building behaviors.
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Second, for goodness sake. We should encourage people to think well because it might reduce the impact of Covid-19 on their cognitive loss? There are many better evidenced and far more consequential reasons to support actions that improve a population's ability to think.

Third, I can't help but feel that this finding creates comfort for people who think they have above average intelligence. Perhaps they will think, 'I will be fine'. We've seen plenty of smart people affected, people giving up on their PhDs because they can't read for more than 10 minutes at a time.

Fourth, surely there are other possible reasons for people with high cognitive reserve having, on average, smaller cognitive deficits. Maybe, higher vaccination rates, and so less severe acute illness and also possibly less risk of Long Covid? Maybe an increased familiarity with the cognitive assessment used to measure the change in cognitive function.
 
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A person’s CR is fostered by a variety of lifetime exposures that include early-life intelligence, vocabulary, educational experience, occupational complexity, leisure activities and social engagement. As CR cannot be measured directly, these socio-behavioral indices, which are thought to play a formative role in CR, are used as proxies. Ideally, multiple proxies would be assessed together to capture their unique contributions to CR (as is the case with a validated CR instrument, such as the CRQ); however, it is more common for only one or two proxies to be assessed in a given study. Studies were eligible for our meta-analysis if at least one proxy was assessed
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... so basically they've found that Long Covid is somewhat more likely to affect people of lower socieconomic status.
 
33 years of experience with cognitive dysfunction in ME/CFS, my reserves have long been depleted.

I have to look up the spelling of every other word and when I don't I make the weirdest typo's. (I was partially taught English in England)

Higher educated means a car in stead of public transport.
Better workspace. A desk to yourself, instead of a counter between you and a shouting customer.
Hands on patients in stead of at the feet end of the bed.
A spacious home or a crowded appartment on the tenth floor with a small elevator etc.
Way more close encounters to get infected with higher viral load.
 
Turtle said:
Higher educated means a car in stead of public transport.
Better workspace. A desk to yourself, instead of a counter between you and a shouting customer.
Hands on patients in stead of at the feet end of the bed.
A spacious home or a crowded appartment on the tenth floor with a small elevator etc.
Way more close encounters to get infected with higher viral load.
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and paid sick leave. (Speaking of "Population-based initiatives [that] may alleviate the PCCD-related public health burden.")
 
I have not read the paper, but given these studies are retrospective they can not make comments on causality. Unless individuals’ cognitive reserve and cognitive functioning were also measured pre Covid, we can not distinguish current cognitive reserve from current Long Covid related cognitive functioning.

Surely this means that we can not be certain that this study is saying anything other than the worse an individual with Long COVID’s cognitive impairment the worse their cognitive impairment.

Similarly we can not be certain we are not seeing ceiling effects inherent in the cognitive assessments used. It could be that the tests at the upper end of cognitive ability are simply not accurate. For example if you have such as an IQ test that only measures up to 110, it means that anyone with a previous IQ of over 110 could suffer a significant unrecognised lowering of their score. For example someone with an original IQ of 110 that drops fifty points would be seen as having a major impairment, but the same drop in someone with an IQ of 160 would go unnoticed. (IQ here is not intended as a realistic usable measure, but rather something that has convenient scoring to illustrate my point.)

I quite like @Turtle ’s concept of depleting our cognitive reserves over time. Certainly for the first two thirds of the thirty years of my ME I was still able to read three or four books a week, write articles and even monographs on academic topics and edit quite lengthy newsletters for local groups. But over the last ten years or so it now takes me on average a year to read a book, if I can complete it at all, and I am unable write anything longer than a social media post or a comment such as this.
 
I could read after getting ME/CFS, but after reading page one and starting on page 2, despite notes, page one was "gone".
A few years back I tried again. Fifty shades of gey, part III. You're allowed to laugh.
I needed a book with an easy plot, check. Not many names, check. Not a lot of factual things, check.
I was disappointed in the rest. One and a half page and it was over and done with. No big loss I forgot that too.
 
Yep. The way I’ve described my cognitive problems is it’s like my RAM (computer short term memory) was reduced by 95%.

So in general my thinking skills or long term memory aren’t too impacted, but my brain gets overloaded way too easily.

Trying to concentrate on writing a simple message + noise of washing machine = too much. Simple things like that.
 
Yann04 said:
So in general my thinking skills or long term memory aren’t too impacted, but my brain gets overloaded way too easily.

Trying to concentrate on writing a simple message + noise of washing machine = too much. Simple things like that.
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Me too. Multi-tasking is impossible now. I also really struggle to follow educational videos - keeping multiple trains of thougths is so hard. It used to be one of my stronger areas.

I did a neuropsych evaluation that came back completely fine. So the underlying ‘mechanisms’ seems to be intact when I’m not in PEM brainfog.
 
Utsikt said:
I did a neuropsych evaluation that came back completely fine.
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Same. Although I was wired as hell to manage to get to the approintment. I think that is a massive confounding factor.

That’s actually the appointment that caused my crash making me unable to speak anymore.

Utsikt said:
So the underlying ‘mechanisms’ seems to be intact when I’m not in PEM brainfog.
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Or neuropsych evaluations weren’t made to detect the changes ME causes.
 
My 'CR' has drastically declined over the 40 years I have had ME/CFS, despite doing all the things you are supposed to do (as best I can) to keep the mind working.

I don't think that can be put down to just normal ageing.
 
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