- The coronavirus targets the lungs foremost, but also the kidneys, liver and blood vessels. Still, about half of patients report neurological symptoms, including headaches, confusion and delirium, suggesting the virus may also attack the brain.
- A new study offers the first clear evidence that in some people, the coronavirus invades brain cells, hijacking them to make copies of itself. The virus also seems to suck up all of the oxygen nearby, starving neighboring cells to death.
- “If the brain does become infected, it could have a lethal consequence,” said Akiko Iwasaki, an immunologist at Yale University who led the work.
- The study was posted online Wednesday and has not yet been vetted by experts for publication. But several researchers said it was careful and elegant, showing in multiple ways that the virus can infect brain cells.
- An image shows brain scans of coronavirus patients from a study published in July. The new study offers the first clear evidence that in some people, the coronavirus invades brain cells, hijacking them to make copies of itself, and the virus also seems to suck up all of the oxygen nearby, starving neighboring cells to death.
- The illness caused by the coronavirus, develop serious neurological complications, including nerve damage.
- In the new study, Iwasaki and her colleagues documented brain infection in three ways: in brain tissue from a person who died of COVID-19, in a mouse model, and in organoids — clusters of brain cells in a lab dish meant to mimic the brain’s three-dimensional structure.
- Other pathogens — including the Zika virus — are known to infect brain cells. Immune cells then flood the damaged sites, trying to cleanse the brain by destroying infected cells.
- The coronavirus seems to rapidly decrease the number of synapses, the connections between neurons.
- The virus infects a cell via a protein on its surface called ACE2. That protein appears throughout the body and especially in the lungs, explaining why they are favored targets of the virus.
- Her team then looked at two sets of mice — one with the ACE2 receptor expressed only in the brain, and the other with the receptor only in the lungs. When they introduced the virus into these mice, the brain-infected mice rapidly lost weight and died within six days. The lung-infected mice did neither.
- Despite the caveats attached to mouse studies, the results still suggest that virus infection in the brain may be more lethal than respiratory infection, Iwasaki said.
- Researchers will need to analyze many autopsy samples to estimate how common brain infection is and whether it is present in people with milder disease or in so-called long-haulers, many of whom have a host of neurological symptoms.
- Forty percent to 60% of COVID-19 patients experience neurological and psychiatric symptoms, said Dr. Robert Stevens, a neurologist at Johns Hopkins University. But the symptoms may not all stem from the virus invading brain cells. They may be the result of pervasive inflammation throughout the body.