Severe COVID-19 looks frighteningly like old age in the human brain, according to post-mortem analysis of 54 healthy and infected individuals.
The study authors say their research is the first to link COVID-19 to molecular signatures of brain aging.
“We observed that gene expression in the brain tissue of deceased COVID-19 patients closely resembled that of uninfected individuals 71 years of age or older,” says public health scientist Jonathan Lee from Harvard University. .
The sample, made up of people between their early twenties and mid-eighties, includes 21 people who had had severe COVID-19, a single asymptomatic individual and 22 people who were not infected with the coronavirus. .
The researchers also compared their results to an uninfected person with Alzheimer’s disease and another group of 9 uninfected people with a history of hospitalization or ventilator treatment.
Using RNA sequencing technology on samples from the prefrontal cortex, scientists found that people with severe COVID-19 exhibited enriched gene expression patterns associated with aging.
The brains of infected people looked more like those of older people in the control group, regardless of their actual age.
Put simply, genes that were typically upregulated in aging, such as those related to the immune system, were also upregulated in severe cases of COVID-19.
At the same time, genes downregulated in aging, such as those related to synaptic activity, cognition, and memory, were also downregulated in severe COVID-19.
“We also observed significant associations of cellular response to DNA damage, mitochondrial function, regulation of stress and oxidative stress response, vesicular transport, calcium homeostasis and pathways. insulin signaling/secretion previously associated with aging processes and brain aging,” the authors write. .
“Overall, our analyzes suggest that many biological pathways that change with natural aging in the brain also change in severe cases of COVID-19.
Since the novel coronavirus SARS-CoV-2 began infecting humans globally, scientists have feared possible long-term consequences.
Brain damage is one of the most problematic outcomes. Severe cases of COVID-19 are often associated with brain fog, memory loss, stroke, delirium or coma. In October 2020, the first brain scans of patients with COVID-19 revealed concerning signs of neurological disruption and impairment.
Subsequent studies have since found that even mild COVID-19 can affect the brain, although it’s still unclear how long these changes might last or how they compare to those with severe COVID-19.
With each passing year, health experts have a better idea of the long-term results this global pandemic could bring. Three years later, things are not looking good.
The results of the current study follow another paper, published earlier this year, which found that the cognitive impact of severe COVID-19 is equivalent to about 20 years of aging.
Neuropathologist Marianna Bugiani from the University of Amsterdam said Nature the new findings open up “a plethora of questions that are important, not only for understanding the disease, but for preparing society for what the consequences of the pandemic might be.”
She also added that these consequences may not be clear for many years to come. And at that time, the global community will likely suffer from repeated COVID-19 infections.
Who knows what impact multiple diseases will have on our long-term cognitive power?
Interestingly, in the current study, the researchers found no genetic evidence of the SARS-CoV-2 virus in the brains of infected patients, suggesting that the neurological consequences of the virus may not be directly due to their presence. in the nervous system.
The authors did, however, find evidence that tumor necrosis factor (TNF), which is associated with inflammation, brain aging and age-induced cognitive decline, was present at higher levels in the brains of those infected. .
Genetic factors associated with antiviral immune responses were also elevated.
The authors argue that both of these pathways “could lead to significant deteriorating effects in the brain in the absence of SARS-CoV-2 neuroinvasion.”
In light of their findings, the team says people recovering from COVID-19 should get neurological follow-ups. If the mere presence of this new virus is enough to trigger inflammation of the brain, it is possible that any infected individual is at risk of brain damage.
Until experts know more, the authors say doctors and patients should focus on other risk factors for dementia that we control, such as weight, alcohol consumption and exercise.
Avoiding future COVID-19 infections to the best of your ability is also probably a good idea.
The study was published in natural aging.
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