#18,724
Within the first few months of COVID-19's arrival it was apparent that the SARS-CoV-2 virus was producing a high morbidity - low mortality pandemic; several times deadlier than than seasonal flu, but not as lethal as might be expected from MERS-CoV, SARS, or avian H5N1.
We've seen ample evidence that the SARS-CoV-2 virus infection extends far beyond just a respiratory disease (see Nature Med. Review: Extrapulmonary manifestations of COVID-19), and cardiac, renal, pulmonary, and neurological impacts became apparent early on.Still, more than 7 million people `officially' died from SARS-CoV-2 globally since December 2019, although a more realistic number has been estimated to be 2 or 3 times higher (see The Lancet Estimating excess mortality due to the COVID-19 pandemic).
JASN: Acute Kidney Injury In Hospitalized Patients With COVID-19
JAMA: Two Studies Linking SARS-CoV-2 Infection To Cardiac Injury
The Lancet: Yet Another Study On Neurological Manifestations In Severe COVID-19 Patients
While somewhere between 98%-99% of those infected with COVID-19 survive their acute illness, we continue to see anecdotal reports and (more recently) studies suggesting that many survivors come away with lingering - sometimes permanent - sequelae.
Whether you call it `Long COVID' or `Post-COVID Syndrome', these persistent after-effects can range from mild or moderate - to disabling - and may even contribute to an early death months or years after the the initial infection.A few of many `post-COVID' studies include:
The Lancet: Long-term Outcomes Following Hospital Admission for COVID-19 Versus Seasonal Influenza
The Lancet: Neurological and Psychiatric Risk Trajectories After SARS-CoV-2 Infection
MMWR: Post–COVID-19 Symptoms and Conditions Among Children and Adolescents
Nature: Long-term Effects of SARS-CoV-2 Infection on Human Brain and Memory
Using near-infrared spectroscopy (NIRS) to measure prefrontal haemodynamics (blood flow), researchers observed:
". . . novel evidence that previously infected students exhibited distinct prefrontal haemodynamic patterns during cognitive engagement, reminiscent of those observed in adults four decades older, and this appeared to be especially true if they reported experiencing brain fog due to COVID-19."
First, the link and abstract from the study (which you'll want to read in its entirety), after which I'll return with a bit more.
Ronan McNeill a. Rebekah Marshall a, Sheelle Anne Fernando a, Olivia Harrison a b c, iana Machado a
https://doi.org/10.1016/j.bbi.2024.12.002
Highlights
- Cognitive engagement induced distinct prefrontal haemodynamic patterns post COVID-19.
- 40% of the undergraduate students reported brain fog due to COVID-19.
- 37 % of the undergraduates exhibited impaired cognition up to 17 months post-infection.
- Brain fog appeared to affect the distinct prefrontal haemodynamic patterns.
Abstract
To date, 770 million people worldwide have contracted COVID-19, with many reporting long-term “brain fog”. Concerningly, young adults are both overrepresented in COVID-19 infection rates and may be especially vulnerable to prolonged cognitive impairments following infection. This calls for focused research on this population to better understand the mechanisms underlying cognitive impairment post-COVID-19.
Addressing gaps in the literature, the current study investigated differences in neuropsychological performance and cerebral haemodynamic activity following COVID-19 infection in undergraduate students. 94 undergraduates (age in years: M = 20.58, SD = 3.33, range = 18 to 46; 89 % female) at the University of Otago reported their COVID-19 infection history before completing a neuropsychological battery while wearing a multichannel near-infrared spectroscopy (NIRS) device to record prefrontal haemodynamics.
We observed that 40 % retrospectively self-reported cognitive impairment (brain fog) due to COVID-19 and 37 % exhibited objective evidence of cognitive impairment (assessed via computerised testing), with some suggestion that executive functioning may have been particularly affected; however, group-level analyses indicated preserved cognitive performance post COVID-19, which may in part reflect varying compensatory abilities.
The NIRS data revealed novel evidence that previously infected students exhibited distinct prefrontal haemodynamic patterns during cognitive engagement,reminiscent of those observed in adults four decades older, and this appeared to be especially true if they reported experiencing brain fog due to COVID-19. These results provide new insights into the potential neuropathogenic mechanisms influencing cognitive impairment following COVID-19.
(SNIP)
7. Conclusions
The present study found evidence suggesting that COVID-19 infection is associated not only with subjective cognitive impairment but also with prolonged objective cognitive impairment, especially in executive functioning, in some but not all undergraduate students.
Moreover, we found novel evidence of distinct task-related anterior prefrontal haemodynamic responses in students reporting a past COVID-19 infection relative to those reporting no past infection, and exploratory analyses suggested this may be particularly true for those who reported experiencing brain fog due to COVID-19. This new information may prove important as we move forward towards developing interventions in response to the mounting evidence that COVID-19 has prolonged influences on brain health.
In closing, we call for scientists to respond urgently to the rapidly increasing prevalence of long covid symptoms pertaining to the brain.
Despite the accumulating evidence to the contrary, much of the world remains in deep denial about the long-term impacts of COVID, and the increased risks from repeated infections.
COVID vaccine uptake has plummeted, despite research showing it can provide significant protection against both severe outcomes and `Long COVID' (see ECDC Rapid Review: Does COVID-19 Vaccination Reduce the Risk and Duration of Post COVID-19 Condition?).To most, COVID is now regarded as little more than a `bad cold'.
While there are still more questions than answers, over the years we've looked at numerous studies (see here, here, and here) linking severe and/or repeated viral infections (including COVID and Influenza) to a variety of neurological diagnoses later in life (see Nature Comms: Revisiting The Influenza-Parkinson's Link).
In 2023 we looked at a study (see Neuron: Virus Exposure and Neurodegenerative Disease Risk Across National Biobanks), which found statistical linkage between viral illnesses and developing neurodegenerative diseases in the future.
While some may argue that the worst of the damage from COVID has already been done, there are other viruses with pandemic potential waiting in the wings, including H5N1 which has been repeatedly linked to neurological impacts (see here, here, here, and here).
Making it imperative that we take the lessons from COVID seriously, else we risk far more damage from the next global health crisis.
