Color & Control:

Long COVID: Lifting the brain fog

By Dr. Henry Mahncke

There are new findings from a group of population health researchers exploring the long-term effects of having had COVID with a long list of symptoms including: fatigue, fever, cough, chest pain, heart palpitations, stomach pain, diarrhea, joint pain, muscle pain, rashes, blood clots, and organ damage. However, the most pervasive and pernicious Long COVID symptoms seem to be cognitive and are often described as “brain fog” which includes memory lapses, difficulty paying focused attention, suppressing distractions, concentrating, planning, reasoning, and making decisions, as well as symptoms of depression, and anxiety.

As a brain scientist, who researches how to improve cognitive function using computerized brain exercises, the symptoms of brain fog associated with COVID sound quite familiar. That’s because we see similar symptoms from other types of brain health issues.

While we are most apt to think of a brain injury as a physical blow to the head (either a concussion, or a more severe injury— in both cases called a traumatic brain injury, or TBI), we now know that brain injuries can arise from a wide range of sources, including external blows (TBIs), as well as internal blows (for example, from a stroke), or from certain medical conditions, such as cancer and cancer treatment (often called chemobrain), chronic heart failure (cardiobrain), HIV-Associated Neurological Disorder (HAND) or long-term substance use disorder, and even just living a long time.

Different pathways
While the paths to cognitive impairment clearly differ, similar symptoms of brain fog arise from many different causes. To put it another way, if I look at the data on cognitive performance on standard neuropsychological tests from a 90 year-old undergoing normal aging, from a 45 year-old with chronic substance use disorder, or from a 25 year-old veteran with concussive injuries from recent wars; it’s hard to say with accuracy which test results belong to which person.

How can that be? The most common symptoms of all those types of brain fog are a slowing of cognitive processing and a slipping in cognitive accuracy.  Brain scientists refer to this as “noise” in the brain—processing speed that is no longer up to handling the varying speeds at which sensory information is delivered throughout the day and accuracy that is a bit like a radio no longer quite tuned precisely to the station’s signal.

In fact, for most of us, our brain speed and accuracy peak in our mid to late twenties, followed by a progressive, slowly advancing, decrease in brain speed and accuracy over the rest of our lives. At first, the changes are not noticeable, but as decades accumulate you find you more often say “Huh, what was that?” Not because you didn’t hear it, but because at that moment the information came in faster than you could accurately process it. This happens in processing information across all your senses. And, if your information processing is noisy, it’s hard to capture, store, and retrieve information. That affects the speed and accuracy of all of your higher brain functions—including memory, reasoning, planning, decision-making, and social cognition, as well as your ability to move confidently and accurately through life.

New discovery
Forty years ago, scientists believed that there was not much you could do to prevent or reverse age-related cognitive decline, nor about event-driven cognitive decline (such TBI, heart failure, chronic substance use disorder, chemobrain, stroke, etc.). The dominant model in science was that the brain was like a computer, with an operating system that got written in your childhood, and, after that, although you could push more information through it, the machine was just destined to wear out over time.

Thanks to work led by Dr. Michael Merzenich in the 1980s, we now know that  the brain remains plastic—capable of chemical, physical and functional change based on your life experience—throughout your life, brain scientists now have a much more dynamic view of your ability to boost brain health and performance at any age or in virtually any condition.

Working with hundreds of university-based research collaborators, we have learned that plasticity-based computerized brain exercises can be used to drive improvements in studies of a wide array of populations with conditions that can include brain fog. That includes more than 60 studies in healthy (mostly older) adults undergoing normal age-related decline where the data is in—the right kind of brain training improves brain health, cognitive function, and real-world performance. There are also 21 studies in the areas of pre-dementia and dementia; nine studies in stroke; three studies in chemobrain; three studies in cardiobrain; three studies in substance use disorder; seven studies in HAND; and nine studies in TBI that show the promise of this science in addressing cognitive health in people in significant clinical need.

Help for Long COVID sufferers?
We don’t know yet if studies (now in the planning stage) in Long COVID populations will show similar results in addressing brain fog. Those studies are still just getting underway. However, in my opinion, based on what we’ve seen in other conditions, there is reason for hope.ϖ

Dr. Henry Mahncke got his PhD in Neuroscience at the University of California, San Francisco. He is the CEO of Posit Science.

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