On today’s podcast “After the Storm: A reflection on life during COVID-19”, we cover the effects on the brain based on the following article and the attached studies.
SARS-COV-2 and the Brain
There is growing evidence that SARS-CoV-2 infection may contribute to the development or exacerbation of Alzheimer's disease (AD) and other forms of dementia. Several studies suggest that COVID-19 can cause physical changes in the brain that resemble those seen in AD, and that amyloid plaques may play a key role in this process.
SARS-CoV-2 Amyloid Properties and Interaction with Amyloid-β (Aβ)
The SARS-CoV-2 virus itself contains several proteins that can form amyloid structures[1]. These viral amyloids may directly contribute to COVID-19-related dementia, or they could trigger the deposition of other amyloids like amyloid-β (Aβ), which is a hallmark of AD[1].
In particular, the SARS-CoV-2 spike protein can bind to and promote the transmission of Aβ between cells[4]. The spike protein also activates Aβ expression and is neurotoxic itself[1]. This interaction between the spike protein and Aβ could potentially lead to the formation of toxic fibrils that contribute to AD-like pathology[1].
Additionally, the amyloid precursor protein (APP), which is cleaved to form Aβ, may facilitate the entry of SARS-CoV-2 into host cells[4]. Increased APP expression has been observed in COVID-19 patients[4], further implicating this protein in the link between the virus and AD.
Brain Changes and Cognitive Decline After COVID-19
Brain imaging studies have revealed structural changes in the brains of COVID-19 patients that are associated with cognitive impairment. These changes include atrophy of the hippocampus, gray matter, and enlargement of the ventricles[2][6]. The affected brain regions are part of dense memory and cognitive networks, possibly explaining the deficits in working memory and executive function observed in some COVID-19 survivors[2].
A study comparing brain scans before and after SARS-CoV-2 infection found greater reduction in gray matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus, as well as markers of tissue damage in regions connected to the olfactory cortex[6]. The infected participants also showed greater cognitive decline between the two timepoints[6].
Potential Mechanisms Linking COVID-19 and Alzheimer's Disease
Several mechanisms have been proposed to explain how SARS-CoV-2 infection may increase the risk of AD:
1. Direct viral invasion of the central nervous system, damaging brain tissue and neurons[2][3][7]
2. Systemic and neuroinflammation, leading to blood-brain barrier disruption and cellular senescence[3][7]
3. Vascular endothelial injury[3]
4. Abnormal APP metabolism and Aβ accumulation[1][3][4][7]
5. Tau hyperphosphorylation and neurofibrillary tangle formation[4]
The ability of SARS-CoV-2 to infect the brain, combined with its amyloidogenic properties and effects on APP processing, creates a concerning link between COVID-19 and increased AD risk. While more research is needed to fully understand this connection, the current evidence highlights the potential long-term neurological consequences of the pandemic.
Protecting the brain from Covid-19 brain damage
The main and only way at this point is to not get SARS-COV-2. It’s particularly important to wear a respirator mask, n95 or better. Avoid high risk environments, such as crowded indoor spaces. If you have the option to install air purification, do so, and open windows when you can. If you can tolerate vaccines, keep yourself regularly updated with your vaccines. For those of you concerned about mNRA vaccines, there are now traditional vaccines, particularly NovaVax.
Sources
[1] SARS-CoV-2 amyloid, is COVID-19-exacerbated dementia an ... frontiersin.org/journals/demen…
[2] Cognitive impairment after long COVID-19: current evidence and ... ncbi.nlm.nih.gov/pmc/articles/P…
[3] The viral hypothesis in Alzheimer's disease: SARS-CoV-2 on the cusp frontiersin.org/journals/aging…
[4] Amyloid precursor protein facilitates SARS-CoV-2 virus entry into ... nature.com/articles/s4139…
[5] SARS-CoV-2-Induced Amyloidgenesis: Not One, but Three ... - NCBI ncbi.nlm.nih.gov/pmc/articles/P…
[6] SARS-CoV-2 is associated with changes in brain structure ... - Nature nature.com/articles/s4158…
[7] Unravelling the connection between COVID-19 and Alzheimer's ... ncbi.nlm.nih.gov/pmc/articles/P…
[8] Is COVID-19 a risk factor for Alzheimer's disease? - News-Medical news-medical.net/news/20231023/…
SARS-COV-2 and the Brain
There is growing evidence that SARS-CoV-2 infection may contribute to the development or exacerbation of Alzheimer's disease (AD) and other forms of dementia. Several studies suggest that COVID-19 can cause physical changes in the brain that resemble those seen in AD, and that amyloid plaques may play a key role in this process.
SARS-CoV-2 Amyloid Properties and Interaction with Amyloid-β (Aβ)
The SARS-CoV-2 virus itself contains several proteins that can form amyloid structures[1]. These viral amyloids may directly contribute to COVID-19-related dementia, or they could trigger the deposition of other amyloids like amyloid-β (Aβ), which is a hallmark of AD[1].
In particular, the SARS-CoV-2 spike protein can bind to and promote the transmission of Aβ between cells[4]. The spike protein also activates Aβ expression and is neurotoxic itself[1]. This interaction between the spike protein and Aβ could potentially lead to the formation of toxic fibrils that contribute to AD-like pathology[1].
Additionally, the amyloid precursor protein (APP), which is cleaved to form Aβ, may facilitate the entry of SARS-CoV-2 into host cells[4]. Increased APP expression has been observed in COVID-19 patients[4], further implicating this protein in the link between the virus and AD.
Brain Changes and Cognitive Decline After COVID-19
Brain imaging studies have revealed structural changes in the brains of COVID-19 patients that are associated with cognitive impairment. These changes include atrophy of the hippocampus, gray matter, and enlargement of the ventricles[2][6]. The affected brain regions are part of dense memory and cognitive networks, possibly explaining the deficits in working memory and executive function observed in some COVID-19 survivors[2].
A study comparing brain scans before and after SARS-CoV-2 infection found greater reduction in gray matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus, as well as markers of tissue damage in regions connected to the olfactory cortex[6]. The infected participants also showed greater cognitive decline between the two timepoints[6].
Potential Mechanisms Linking COVID-19 and Alzheimer's Disease
Several mechanisms have been proposed to explain how SARS-CoV-2 infection may increase the risk of AD:
1. Direct viral invasion of the central nervous system, damaging brain tissue and neurons[2][3][7]
2. Systemic and neuroinflammation, leading to blood-brain barrier disruption and cellular senescence[3][7]
3. Vascular endothelial injury[3]
4. Abnormal APP metabolism and Aβ accumulation[1][3][4][7]
5. Tau hyperphosphorylation and neurofibrillary tangle formation[4]
The ability of SARS-CoV-2 to infect the brain, combined with its amyloidogenic properties and effects on APP processing, creates a concerning link between COVID-19 and increased AD risk. While more research is needed to fully understand this connection, the current evidence highlights the potential long-term neurological consequences of the pandemic.
Protecting the brain from Covid-19 brain damage
The main and only way at this point is to not get SARS-COV-2. It’s particularly important to wear a respirator mask, n95 or better. Avoid high risk environments, such as crowded indoor spaces. If you have the option to install air purification, do so, and open windows when you can. If you can tolerate vaccines, keep yourself regularly updated with your vaccines. For those of you concerned about mNRA vaccines, there are now traditional vaccines, particularly NovaVax.
Sources
[1] SARS-CoV-2 amyloid, is COVID-19-exacerbated dementia an ... frontiersin.org/journals/demen…
[2] Cognitive impairment after long COVID-19: current evidence and ... ncbi.nlm.nih.gov/pmc/articles/P…
[3] The viral hypothesis in Alzheimer's disease: SARS-CoV-2 on the cusp frontiersin.org/journals/aging…
[4] Amyloid precursor protein facilitates SARS-CoV-2 virus entry into ... nature.com/articles/s4139…
[5] SARS-CoV-2-Induced Amyloidgenesis: Not One, but Three ... - NCBI ncbi.nlm.nih.gov/pmc/articles/P…
[6] SARS-CoV-2 is associated with changes in brain structure ... - Nature nature.com/articles/s4158…
[7] Unravelling the connection between COVID-19 and Alzheimer's ... ncbi.nlm.nih.gov/pmc/articles/P…
[8] Is COVID-19 a risk factor for Alzheimer's disease? - News-Medical news-medical.net/news/20231023/…
SARS-COV-2 and The Brain, Episode 2
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