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Covid and the Brain

The proper name here is “COVID-19,” but I will be lazy and just call it “Covid.”

For many of us who are vaccinated, getting Covid is typically not something that will send us to the hospital. “There have been some breakthrough COVID cases among the vaccinated population. But the vast majority of hospitalizations and ICU cases are among unvaccinated people” [].

But this post is not about vaccination.

The Covid impact

If you get Covid, your immediate bout with the disease is just a small part of the story.

When I had Covid in May 2022 I felt horrible for five days, but frankly I’ve had flus that hit me harder. What made my bout with Covid worse than a mere flu was how it affected me after those first five days: my energy was completely depleted, and it took about two full months before I felt completely recovered. But luckily, I did fully recover.

This disease affects many people in many different ways, so you really can’t predict how it will hit you. I was drained of energy. Others lose their sense of taste or smell. Still others are not able to feel their limbs, thus affecting their ability to walk normally. The list of impacts goes on, and the duration of these symptoms varies widely.

Imagine being a person with an active life and a career you enjoy, but then after a bout of Covid, you never return to normal. For some this means losing their sense of smell (which is more impactful than you think), but for others it means struggling to walk, or worse. Many of us are or will be lucky that Covid will hit us for a short time and then we can go back to our life as usual. But for some people, it turns their lives upside down and they have no way of knowing if they are looking at this new, unpleasant life for another few months or years, or forever.

But this post is not really about long-term physical effects of Covid, either.

This post is about the effect of Covid specifically on the brain. I am not minimizing the physical impacts that long Covid is having on so many in our population. These symptoms are absolutely in no way trivial and are very concerning.

Let’s focus on the brain.

Covid and the brain

While most of us hear about the coughing, the lack of energy, and other symptoms, few are thinking about how this affects our brains.

Another symptom of Covid infection that many have experienced is confusion, impaired memory, and other cognitive issues: the Covid fog. When I was struggling with my lack of energy after Covid, I also experienced a general lack of mental energy: I was much less mentally robust, slower with my thinking, and frequently at a complete loss for the right words for things.

Frankly this was very frightening, but as my general energy level returned, my brain’s energy returned as well. This taste of what it was like to experience a depletion of my mental abilities was a very sobering experience.

We know that the brain is affected by Covid, but what is not yet known is how long this effect lasts. I was lucky to be back to normal after two months. But for some, the symptoms are lingering on. Is it possible that for some people these symptoms could be permanent? Or may reappear later in life?

There is much more testing needed, but some studies are showing that those who get Covid may experience a lasting or permanent impact in their brains. And some research indicates that, even if the individual feels mentally sound during and after their Covid experience, they may now have an increased chance of getting Alzheimer’s, Parkinson’s, and other brain diseases later in life. [I have added links to sources for this cliam at the end of this post.]

If you are among the lucky who have no genetic propensity for these diseases then you might not care much about this. But for those of us who already have a real risk of getting one of these diseases, increasing that risk by anything at all is very concerning. One study suggests that getting Covid could triple your chance of getting Alzheimer’s. If your likliness for getting Alzheimer’s  went from 0.003% to 0.009%, you could reasonably still feel pretty safe. But if you had a 4% risk of getting Alzheimer’s, how much hassle would it be worth to you to avoid something that could jump that risk up to 12%?

So, for now, it’s still “No to Normal”

There are some who say that Covid is now endemic, part of our normal lives. They’re right: it’s permeated nearly everywhere and we need to learn to live with it.

But if there is even a small chance that getting Covid means I will may have permanent memory or other cognitive declines that could affect my ability to function or to work, potentially for the rest of my life — let alone an increased risk of Alzheimer’s and more — then maybe we should continue to be careful.

As my partner put it: COVID is not quite three years old. It’s evident that neural damage can last that long, but it’s impossible to predict how “permanent” that damage is.

So, forgive me for not agreeing that it is time to “go back to normal.” I agree that Covid is endemic and we need to find a way to live our lives and grow and thrive as individuals and communities despite it. But I think we have more to learn first. Until we do, then “normal” is something we need to redefine, not go back to. And in the meantime, we need to stop pretending that there are no risks.

The research

Don’t just take my word for it that our brains are potentially in danger from Covid. Below are links to some of the studies I mentioned earlier in this post, and more. They are from a wide variety of sources, reach a variety of conclusions, and are listed here in no particular order.

I’ll add to this post from time to time as new research comes available. Read these articles. Think about them and share them.

And be careful out there!

Oxford study finds increased dementia risk 2 years after COVID infection
[August 17, 2022 New Atlas]  “…an increased risk of mood disorders such as depression and anxiety, following SARS-CoV-2 infection, returns to normal after a few months but increased rates of dementia are still being detected in older adults up to 24 months after the acute disease…. The strength of this study is in its robust control group allowing for a greater insight into the novel risk caused by SARS-CoV-2, as opposed to any general increased risk from other kinds of respiratory infection. In this case the study does suggest COVID may increase one’s risk of dementia but exactly how that could be happening is still unclear.”  [Full source article in The Lancet]

COVID-19 Positive Patients at Far Higher Risk of Developing Serious Neurodegenerative Disorders
[]  “COVID-19 positive outpatients are at a far increased risk of neurodegenerative disorders compared with individuals who tested negative for the virus… Out of 919,731 individuals that were tested for COVID-19 within the study, researchers found that the 43,375 people who tested positive had a 3.5 times increased risk of being diagnosed with Alzheimer’s disease, 2.6 times with Parkinson’s disease, 2.7 times with ischaemic stroke, and 4.8 times with intracerebral hemorrhage (bleeding in the brain)” [Full source article in Frontiers in Neurology (via ResearchGate)]

The hidden long-term cognitive effects of COVID-19
[March 4, 2021 – Harvard Health Publishing]  “More than 40% of patients with COVID showed neurologic manifestations at the outset, and more than 30% of those had impaired cognition… New research is now suggesting that there may be long-term neurologic consequences in those who survive COVID infections, including more than seven million Americans and another 27 million people worldwide. Particularly troubling is increasing evidence that there may be mild — but very real — brain damage that occurs in many survivors, causing pervasive yet subtle cognitive, behavioral, and psychological problems.”

Cognitive impairment and functional change in COVID-19 patients undergoing inpatient rehabilitation
[Sept. 2021 – PubMed (abstract)]    “Cognitive impairment is increasingly recognized as a sequela of COVID-19… Cognitive impairment is frequent among COVID-19 patients, but improves over time and is associated with functional gain during inpatient rehabilitation…” [Full source article in the International Journal of Rehabilitation Research]

Neuropathogenesis and Neurologic Manifestations of the Coronaviruses in the Age of Coronavirus Disease
[May 29, 2020 – JAMA: Journal of the AMA]  “Emerging evidence suggests COVID-19 has neurologic consequences… Further neuropathological studies will be crucial to understanding the pathogenesis of the disease in the central nervous system… it remains unknown to what extent SARS-CoV-2 damages the central nervous system (CNS) or if neurological symptoms are attributable to secondary mechanisms.”

New study shows how having had COVID-19 may negatively impact your performance at work
[June 8, 2022 – Science Daily]  “Individuals who contract COVID-19 often experience memory, attention, and concentration problems, even after recovering from the initial illness. A new study from the University of Waterloo shows individuals who had contracted COVID-19 reported significantly more cognitive failures at work.”

Covid-19 linked to cognitive decline, acceleration of Alzheimer’s-like symptoms
[July 29, 2021 – CNN]  “Researchers are finding memory issues and biological markers similar to those seen in Alzheimer’s disease patients. … It’s too soon to tell whether the cognitive issues will worsen over time… or if these patients will recover… I’m trying to understand whether the virus accelerates a pre-existing condition, or if it causes a new Alzheimer’s-like process to begin and then progress, or if it behaves as a fixed problem that will completely recover… We just don’t know that yet.”

Many Covid patients have memory problems months later, new study finds
[Oct. 23, 2021 – NBC News]
“Many people who have recovered from Covid-19 infection are still experiencing cognitive impairment more than seven months later… As many as 24 percent of people who have recovered from Covid-19 continue to experience some sort of cognitive difficulties, including problems with memory, multitasking, processing speed and focusing… even younger patients who had a mild case of the disease reported cognitive difficulties…”

Cognitive symptoms after COVID-19
[Dec. 14, 2021 – Neurology Perspectives]  “SARS-CoV-2 infection frequently causes neurological symptoms. Cognitive alterations are among the most frequent symptoms, and may persist beyond the acute phase of infection… Post-COVID-19 cognitive symptoms, unlike those associated with other viral illnesses, have been observed in patients with mild infection, and present some atypical features. Cognitive symptoms may last longer in COVID-19 than in other infectious processes, and more frequently affect young people. ”

Mild COVID Infection Can Shrink Brain, Speed Cognitive Decline
[March 12, 2022 – ALZForum]  “Some small imaging studies have shown brain damage after hospitalized people had recovered from severe COVID-19. Can milder bouts injure the brain, too? … Four months after a mild COVID infection, adults ages 51 to 81 had slightly thinner gray matter and more signs of tissue damage in their olfactory areas than they did before infection, even after accounting for age-related brain changes that showed up in uninfected controls. This is the first longitudinal study on the brain effects of COVID that compares MRI scans before and after infection.”

The neurological impact of COVID-19: What we know so far
[Feb. 3, 2022 – Medical News Today]  “Neurologic complications from COVID-19 are common and can range from decreased mental clarity to stroke… Prior assumptions that the virus directly affected brain cells have been disproven. Instead, nervous system injury is likely a result of severe inflammation and neurovascular injury. Neurologic insults from SARS-CoV-2 infection could increase the incidence and severity of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease, in future generations.”