A study from the Icahn School of Medicine in New York showed that brain changes after a COVID-19 infection are similar to those observed in people with Alzheimer’s dementia.
Furthermore, in people with Alzheimer’s, the SARS-CoV-2 virus disrupts the blood-brain barrier integrity and causes neuroinflammation that can make dementia worse.
The study involved post-mortem examination of the brains of four groups of patients with an average age of 79.6 who passed away with COVID-19.
- The control group (Subjects without COVID-19 infection and dementia)
- Those infected with SARS-CoV-2 but without Alzheimer’s disease
- Those with Alzheimer’s disease
- Alzheimer’s disease patients infected with COVID-19
Two parts of the brain from post-mortem samples were examined. The cortical Broadman area 9 (BA9) of the frontal cortex and the hippocampal formation (HF). Both serve vital brain functions like memory, verbal fluency, and inductive reasoning.
The study found hundreds of genes were either up-regulated or downregulated in the COVID-19 groups and the Alzheimer’s dementia group. In contrast, those brain changes were not found in the non-infected, no dementia group.
The changes in the genes expressed resulted in the formation of proteins that increase inflammation, premature aging of the cells, and a disruption of the blood-brain barrier. The barrier protects the brain from unwanted substances damaging the sensitive brain cells.
The overall result is that the brains of people who died from COVID-19 resembled the brain of Alzheimer’s disease patients.
The figures below show the similarities of the gene changes in the Broadman Area 9 (BA9) and Hippocampal Formation (HF) in the brains of Alzheimer’s dementia (AD), COVID-19 patients (SARS-CoV-2), and COVID-19 AD patients.
Shades of different colors represent each gene expressed. Notice that the gene changes are similar in all three, and the color intensities are higher in the AD+SARS-CoV-2 group. The vertical bars on the right are the number of up-regulated and down-regulated genes.
Among the Alzheimer’s group infected with the SARS-CoV-2, the resulting inflammation resulted in more neuroinflammation that can be clinically translated to a deterioration of Alzheimer’s symptoms.
According to the authors, their findings support the discovery of Zhou and colleagues, who found that COVID-19 and Alzheimer’s patients have the same changes in the brain.[2]
The finding from our study suggests that SARS-CoV-2 and AD-infected individuals share similar alterations of regulatory patterns of immune-inflammatory pathways and pathways involved with cognition, as suggested by recent meta-analyses showing shared neuroinflammation and microvascular injury, in particular, AD and SARS-CoV-2 infected individuals (2)
Long COVID
Their finding may explain why some people with Long COVID or Post Acute Sequelae of COVID-19 (PASC) continue to have neurologic symptoms weeks after they recover from the infection.
The similarities of transcriptional profiles and cellular pathophysiology in SARS-CoV-2 and SARS-CoV-2 infected individuals support the potential role of SARS-CoV-2 infection on the cental nervous system, leading to neuro-PASC symptoms such as brain fog and memory loss.
Brain deterioration
Due to the inflammation, some brain cells may get damaged to initiate or worsen dementia symptoms.
They cited the work of Wang et al. [3], who found that COVID-19 is associated with new-onset Alzheimer’s disease.
Interestingly, a large retrospective study of patients 65 years or older revealed that patients with SARS-CoV-2 were at an increased risk for a new Alzheimer’s Disease diagnoses within a year of their SARS-CoV-2 diagnosis, with the most significant risk seen among those 85 years and older.[3]
Comment
The research findings of Griggs and colleagues should alert us, including physicians, that new-onset or decline in memory and cognitive functions in the elderly may not only be due to the progression of Alzheimer’s but may also be due to Long COVID. It is estimated that about 10% of the elderly experience Long COVID.
These patients’ identification and proper diagnosis are needed to get appropriate care. The Front Line COVID-19 Critical Care Alliance has a protocol for treating PASC.
I discussed it at The I-RECOVER Management Protocol for Long Haul COVID-19 Syndrome.
If you know someone who may have Long COVID, a search on the internet may
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References:
- Griggs, E. et al. Molecular and cellular similarities in the brain of SARS-CoV-2 and Alzheimer’s disease individual.
- Zhou Y et al. Network medicine links SARS-CoV-2/COVID-19 infection to brain microvascular injury and neuroinflammation in dementia-like cognitive impairment. Alzheimers Res Ther. 2021 Jun 9;13(1):110. doi: 10.1186/s13195-021-00850-3. PMID: 34108016; PMCID: PMC8189279.
- Wang L et al. Association of COVID-19 with New-Onset Alzheimer’s Disease. J Alzheimers Dis. 2022;89(2):411-414. doi: 10.3233/JAD-220717. PMID: 35912749.
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