What Does Covid-19 Do to Your Brain?
Scientists are racing to figure out why some patients also develop neurological ailments like confusion, stroke, seizure, or loss of smell.
By now you're probably familiar with the typical hallmarks of Covid-19, the disease that has so far killed more than 125,000 people around the world: fever, cough, difficulty breathing. But stories of other, stranger symptoms—headaches, confusion, seizures, tingling and numbness, the loss of smell or taste—have been bubbling up from the frontlines for weeks. Published data on how frequently the disease manifests in these types of neurological symptoms is still sparse, and experts say they likely occur in a minority of the 2 million officially tallied Covid-19 infections worldwide. But for physicians, they are important because some of these new symptoms may require a different line of treatment, one designed for the brain rather than the body.
“The medicines we use to treat any infection have very different penetrations into the central nervous system,” says S. Andrew Josephson, a neurologist at UC San Francisco. Most drugs can't pass through the blood-brain barrier, a living border wall around the brain. If the coronavirus is breaching the blood-brain barrier and infecting neurons, that could make it harder to find effective treatments.
Right now, many doctors are trying a two-pronged approach. The first is finding antiviral drugs that can knock back how fast SARS-CoV-2 replicates. They often combine that with steroids, to prevent the immune system from going overboard and producing inflammation that can be damaging on its own. If doctors knew people had coronavirus in their brains, that would alter the equation. Unlike the lungs, the brain can't be put on a ventilator.
“We've been telling people that the major complications of this new disease are pulmonary, but it appears there are a fair number of neurologic complications that patients and their physicians should be aware of,” says Josephson. Any serious viral infection is likely to affect the central nervous system, either through a direct infection or indirectly through inflammation caused by an immune system response.
More research is needed, but this is hard due to the realities of trying to document a new disease while being buried beneath the first wave of the outbreak. With hospitals in Wuhan overwhelmed by a crush of Covid-19 patients during the first half of February, doctors often had to rely on patients' own descriptions of their symptoms. There was a lot they couldn't do, like imaging people's brains, measuring their nervous system activity, or looking for copies of the coronavirus in their spinal fluid. But that's the kind of data that would help pinpoint what's disrupting brain function for some Covid-19 patients.
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