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)