- 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)