Washington: According to a report published Wednesday, headaches, nausea, and delirium suffered by some Covid-19 patients may be the result of the coronavirus directly entering the brain.
The study is still preliminary – but presents many new lines of evidence to support what had previously been a largely untested hypothesis.
S Andrew Josephson, chair of the department of neurology at the University of California, San Francisco, praised the methods used in the research and said "It is incredibly necessary. To understand whether or not there is clear viral involvement in the brain."
But he added he would remain cautious until peer review was performed on the paper. It would not be entirely surprising if SARS-CoV-2 could penetrate the blood-brain-barrier, a structure that covers the blood vessels of the brain and attempts to block foreign substances.
For example, the Zika virus does this too – resulting in severe damage to the fetal brains. But until now, doctors had suspected that the neurological symptoms observed in nearly half of all patients could be the result of an irregular immune response known as a
Cytokine storm that triggers brain inflammation – rather than directly entering the virus.
– Unclear prevalence – Iwasaki, and colleagues wanted to resolve the problem in three ways: infecting lab-grown mini-brains known as brain organoids, infecting mice, and analyzing the brain tissues of
The team found that the SARS-CoV-2 virus can infect neurons in the brain organoids, and then hijack the machinery of the neuron cell to create copies of itself. Infected cells in turn spurred the death of neighboring cells by consuming their supply of oxygen.
However, the team found that the organoids had enough ACE2 to allow entry of the virus, and the proteins were also present in deceased patients' brain tissue. They also conducted a spinal tap on a delirium-stricken hospitalized Covid-19 patient and found the person in their spinal fluid had neutralizing antibodies against the virus – more evidence in
Those infected with the lungs displayed some signs of lung damage, while those infected with the brain quickly lost weight and died rapidly, suggesting possibly increased legality when the virus
Finally, they studied the brains of three patients who died from serious complications linked to Covid-19, discovering signs of the virus to varying degrees in both. Intriguingly, the infected areas showed no signs of being infiltrated by immune cells, such as T-cells, that rushed to the site of other viruses such as Zika or herpes to
This may indicate that the overwhelmed immune response is known as a cytokine storm, which may not be the main cause of neurological symptoms due to most of the damage. It was hypothesized that the nose was able to provide the brain route, however, the authors wrote that this needed to be confirmed via further research.