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  • - My brain doesn't work most of the time,

  • and I can't describe it any better than that.

  • The things I used to love doing,

  • I can't do anymore, because I don't remember how.

  • I so badly want to be who I was pre-COVID,

  • and I try to be that person,

  • and it's just not there.

  • - [Narrator] Rebecca Meyer is one of thousands

  • of coronavirus survivors who are plagued

  • with long-term cognitive health issues

  • associated with COVID-19.

  • - What's really concerning is the vast spectrum

  • of symptoms that fluctuate over time,

  • even neurological and psychologic effects.

  • - [Narrator] The severity of these issues

  • and how long they last is still unclear.

  • But, that's starting to change.

  • New research shows that the coronavirus

  • may have more wide-ranging effects

  • on the brain than previously thought.

  • - We know that it affects the brain

  • because of some of the symptoms

  • that the patients are reporting.

  • They're reporting memory issues,

  • or they're reporting forgetfulness,

  • they're reporting some brain fog,

  • they're reporting some anxiety, some depression.

  • - [Narrator] Doctors say some patients

  • are also experiencing inattention

  • and symptoms that resemble chronic fatigue syndrome,

  • and that many are reporting them months

  • after initially getting sick.

  • - Patients that, often times, are

  • in their 20s, 30s, 40s,

  • never had these symptoms before,

  • or if they did, they were mild.

  • - [Narrator] This isn't the first time

  • researchers have seen this.

  • Other viral outbreaks like SARS, MERS, Ebola,

  • H1N1, and the Spanish flu

  • have also caused long-term symptoms

  • related to the nervous system.

  • - We know that from SARS,

  • there were long-term cognitive changes.

  • There are 50 or 100 patients

  • that were able to be followed up,

  • and we saw long-term neuropsychiatric changes,

  • changes in levels of post-exertional fatigue,

  • levels of depression and anxiety,

  • levels of ability to go back to work.

  • - [Narrator] Long-term COVID-19 research

  • is still in its early stages.

  • Right now, scientists still aren't sure

  • how the coronavirus affects neurological functioning.

  • In certain infections,

  • viruses can actually enter the brain.

  • If the brain's immune system reacts,

  • that can lead to swelling,

  • also known as encephalitis.

  • While this can happen with the coronavirus,

  • researchers say it's very rare.

  • Instead, it's more likely

  • that the virus does its damage

  • through an overactive immune response

  • throughout the body.

  • This can also lead to inflammation,

  • which can harm neurons,

  • cells that are essential to cognitive functioning.

  • Here's a closer look at how that happens.

  • The virus that causes COVID-19

  • usually enters the body

  • through the nose, mouth, or eyes.

  • From there, it can infect the respiratory system,

  • traveling down the trachea to the lungs,

  • where it can enter the bloodstream.

  • To fight off this infection,

  • the body sends a flood of immune system cells

  • and molecules known as cytokines.

  • These cause inflammation,

  • which can make it easier for blood to form clots.

  • When these clots build up, they can prevent oxygen

  • from reaching vital organs, including the brain,

  • which can cause cells to die.

  • In the most severe cases,

  • this can lead to strokes.

  • But it's not just the lack of oxygen

  • that can cause damage.

  • Inflammation can also harm

  • the protective barrier that shields the brain,

  • making the organ more vulnerable.

  • - The brain is protected

  • by something we call the blood-brain barrier,

  • and the blood-brain barrier is

  • not really a physical barrier,

  • but it's a biochemical barrier,

  • and it allows certain things to go in.

  • Cells can go in and out.

  • Certain nutrients can go in and out.

  • - [Narrator] The blood-brain barrier does a good job

  • of preventing toxins and pathogens

  • from entering the brain.

  • But new research shows that the coronavirus

  • can infect and disrupt the cells

  • that line the barrier walls.

  • This is called the endothelium.

  • This disruption causes the body's immune system

  • to kick further into overdrive,

  • leading to inflammation in the brain.

  • - Imagine a road that is paved

  • by endothelial cells, and along that road,

  • you have immune cells, like cars,

  • that are rolling along that road.

  • If a virus or something comes along

  • and destroys that road,

  • the lining, the endothelial cells,

  • and it becomes rough and difficult to ride along,

  • and the immune cells now start bumping along,

  • they become activated, and they now

  • start producing all sorts of free radicals

  • and inflammatory factors.

  • That repair process, if it goes on too long,

  • you now have ongoing chronic inflammation.

  • We suspect that that is what happens

  • in the ongoing process of long haulers.

  • - [Narrator] And this isn't the only way

  • that inflammation can attack the nervous system.

  • Cells supporting the olfactory neurons in the nose

  • can also be damaged by the infection.

  • Scientists suspect that when these cells die,

  • patients might experience a loss of taste and smell.

  • Research from other infections

  • shows that inflammatory signals

  • can make their way up nerves into the brain,

  • causing even more inflammation.

  • These are some of the ways

  • that scientists think inflammation

  • can affect the nervous system,

  • and they could explain

  • why so many long-haul patients

  • are experiencing neurological problems.

  • So what does this mean

  • for those with persisting symptoms?

  • Past epidemics offer some clues.

  • Researchers studying the 1918 Spanish flu

  • found that a number of survivors showed symptoms

  • related to Parkinson's decades later.

  • More recently, physicians have reported tremors

  • in a few COVID-19 patients,

  • but much of the research is still in animals.

  • - [Dr. Tansey] It may range from some effects

  • that are temporary

  • to some that may be permanent,

  • including loss of certain circuits

  • that may not come back.

  • Those may be associated with things

  • like dementia or motor symptoms,

  • things like Parkinsonism,

  • things like Alzheimer's and other dementias.

  • - [Narrator] But this idea is preliminary.

  • - It's a prediction based on past events,

  • where we know that viruses that affect the brain,

  • directly or indirectly, may have effects.

  • And so, we'll have to see.

  • It'll be a matter of time

  • in trying to test it.

  • - [Narrator] Even so, scientists say these findings

  • are an important step forward,

  • and that the research could help find answers,

  • not just for COVID-19 patients,

  • but for those with other brain diseases too.

  • - One reason to hope

  • is that I also have seen patients

  • who have recovered within weeks to months.

  • People who

  • may have responded well to some treatment

  • for some underlying associated brain fog symptoms,

  • it seems that the underlying cognitive

  • dysfunction has been improving

  • without any strong immunomodulatory drugs, for example.

  • That said,

  • the jury is still out.

  • - Hopefully these issues that I'm having,

  • and other people, it's not lifelong.

  • That's what we're hoping.

  • It feels like it is right now.

  • It feels like we're gonna be sick forever.

  • We just have to hope that that's not the case.

  • (dramatic music)

- My brain doesn't work most of the time,

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冠状病毒如何影响大脑背后的科学(The Science Behind How the Coronavirus Affects the Brain | WSJ)

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    joey joey 發佈於 2021 年 05 月 30 日
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