COVID and MCI/Dementia

I was recently asked to discuss the impact of COVID on Mild Cognitive Impairment and Dementia by our HABIT alumni.  Folks had heard that COVID may increase the risk of MCI or dementia, and wanted clarification.

First, there is still so much to learn about how COVID may impact cognitive function in general.  To be brief, (as I think this topic deserves a post of its own) the early research suggests that the most risk of cognitive dysfunction is amongst those who are hospitalized for COVID, particularly those who are so severely ill they need help with breathing through intubation. There have been some reports of lasting impacts of lowered attention, concentration, thought speed, and executive function in these cases. If you had COVID and were treated on an outpatient basis, it doesn’t seem you should worry too much about your odds of serious cognitive dysfunction.

But what if you already have MCI and are trying to do all you can to maximize your cognition and prevent dementia? Well, you want to minimize your risk of significant illness from COVID by following the latest CDC guidelines to prevent infection. Just as you try to prevent the severe potential health risks and lasting physical limitations that may come with more severe COVID, you want to minimize the risk that COVID may worsen your cognitive abilities further. We think of things like this as “exacerbating factors” to cognitive function, or something that takes your already struggling memory or cognitive processes and makes it even harder to remember or think clearly. Other exacerbating factors for MCI are things like lack of sleep or depression.  Exacerbating factors do not CAUSE the disease behind dementias (lack of sleep doesn’t CAUSE Alzheimer’s), but may make symptoms worse.

That being said, over a long period of time, some illnesses or brain “stressors” may increase your odds of later developing dementia. Let’s imagine that your brain has a “bucket” of all the things it can tolerate before it overflows and you show signs in daily life of cognitive impairment. One really bad car accident or perhaps a stroke could overflow that bucket quickly. Alzheimer’s disease pathology in your brain is like a steady, slow drip into the bucket that takes perhaps even decades to slowly fill until it overflows and you to show outward signs of dementia. However, while this slow, steady drip is occurring in the background, other things may slip into your bucket. Maybe a concussion in college that you recovered from added a splash to your bucket, or a long time in anesthesia for knee replacement surgery added another splash to your bucket. Maybe you drank too much alcohol over your life, or had a couple “mini strokes” – that’s more in the bucket. With these additional splashes, it takes less time for that steady drip of Alzheimer’s to overflow your bucket. To think of it a different way, if you were destined to have a dementia like Alzheimer’s disease, you may show signs of it sooner the more of these other stressors or illnesses you also have in your life. Maybe you would only have shown signs of dementia if you lived to be 110, but since all these other things were also adding to your bucket over the years, you show signs of dementia at 80. Sometimes the knee surgery or the mild concussion from a slip and fall is that last splash in the bucket, and people think their cognitive issues are from the surgery or from a minor fall. The truth is, the bucket was almost full already from Alzheimer’s and that was the last splash before the Alzheimer’s became clear in daily life.

What about the question that prompted this blog – does COVID increase the risk or even cause MCI or dementia? We’ve been dealing with the pandemic for not quite 2 years now, and even the earliest published works about the cognitive impact have really just been in the last several months. So, it is simply too soon for anyone to have done the long-term research asking if COVID increases risk to later develop MCI or dementia. However, we can make a reasonable guess that severe COVID doesn’t cause Alzheimer’s disease, but is another something adding to our brain’s bucket.

We are still working on “cures” or things that can help empty some of the bucket. In the future I’ll write something about how to increase the size of your bucket, so you can tolerate more. For now, try to keep safe from COVID for all the same reasons everyone else does:  to prevent serious illness or death.