October 3, 2023

Even Mild Cases of COVID-19 Leave a Mark on the Brain – And It’s Not Yet Clear How Long It Lasts

The brand-new findings, although initial, are raising concerns about the potential long-lasting results of COVID-19
With more than 18 months of the pandemic in the rearview mirror, scientists have been gradually collecting essential and new insights into the effects of COVID-19 on the body and brain. These findings are raising concerns about the long-lasting effects that the coronavirus might have on biological processes such as aging.
As a cognitive neuroscientist, my previous research study has actually concentrated on understanding how regular brain modifications associated with aging affect individualss ability to move and think– especially in midlife and beyond. However as more evidence came in revealing that COVID-19 could impact the body and brain for months or longer following infection, my research study team became interested in exploring how it may also affect the natural process of aging.
Peering in at the brains action to COVID-19.
In August 2021, a initial however large-scale study investigating brain changes in people who had actually experienced COVID-19 drew a good deal of attention within the neuroscience neighborhood.

Noticeably, the brain areas that the U.K. researchers discovered to be affected by COVID-19 are all linked to the olfactory bulb, a structure near the front of the brain that passes signals about smells from the nose to other brain regions. Our labs work shows that as individuals age, the brain believes and processes details in a different way. When it comes to brain structure, we generally see a decrease in the size of the brain in grownups over age 65. Distinctions can be seen across numerous regions of the brain. There is likewise typically a boost in cerebrospinal fluid that fills space due to the loss of brain tissue.

Because study, scientists depend on an existing database called the UK Biobank, which contains brain imaging information from over 45,000 individuals in the U.K. going back to 2014. This indicates– most importantly– that there was standard information and brain imaging of all of those people from prior to the pandemic.
The research team analyzed the brain imaging data and after that restored those who had actually been detected with COVID-19 for extra brain scans. They compared people who had actually experienced COVID-19 to individuals who had not, carefully matching the groups based on age, sex, standard test date and research study location, along with common risk aspects for disease, such as health variables and socioeconomic status.
The team discovered significant differences in gray matter– which is made up of the cell bodies of nerve cells that process info in the brain– between those who had actually been contaminated with COVID-19 and those who had not. Particularly, the density of the noodle tissue in brain areas known as the temporal and frontal lobes was reduced in the COVID-19 group, varying from the normal patterns seen in the group that hadnt experienced COVID-19.
In the basic population, it is typical to see some change in gray matter volume or thickness over time as individuals age, however the modifications were bigger than normal in those who had been infected with COVID-19.
Surprisingly, when the scientists separated the individuals who had extreme sufficient disease to need hospitalization, the results were the same as for those who had experienced milder COVID-19. That is, individuals who had actually been infected with COVID-19 revealed a loss of brain volume even when the illness was not severe sufficient to require hospitalization.
Lastly, researchers likewise investigated modifications in efficiency on cognitive jobs and discovered that those who had contracted COVID-19 were slower in processing details, relative to those who had not.
While we need to beware translating these findings as they await formal peer review, the big sample, pre- and post-illness information in the very same people and careful matching with people who had not had COVID-19 have made this preliminary work especially important.
What do these modifications in brain volume mean?
Early on in the pandemic, one of the most common reports from those infected with COVID-19 was the loss of taste and smell.
Some COVID-19 patients have experienced either the loss of, or a decrease in, their sense of smell.
Noticeably, the brain regions that the U.K. scientists discovered to be impacted by COVID-19 are all connected to the olfactory bulb, a structure near the front of the brain that passes signals about smells from the nose to other brain areas. We typically talk about the temporal lobe in the context of aging and Alzheimers disease because it is where the hippocampus is located.
The sense of odor is also important to Alzheimers research study, as some data has recommended that those at danger for the disease have actually a minimized sense of odor. While it is far too early to draw any conclusions about the long-lasting impacts of these COVID-related changes, examining possible connections in between COVID-19-related brain modifications and memory is of fantastic interest– particularly provided the regions implicated and their importance in memory and Alzheimers illness.
Looking ahead
These brand-new findings cause essential yet unanswered questions: What do these brain changes following COVID-19 mean for the process and rate of aging? And, over time does the brain recuperate to some degree from viral infection?
These are open and active locations of research study, some of which we are beginning to do in my own laboratory in conjunction with our ongoing work investigating brain aging.
Brain images from a 35-year-old and an 85-year-old. Green arrows point to locations where there is more space filled with cerebrospinal fluid (CSF) due to reduced brain volume. The purple circles highlight the brains ventricles, which are filled with CSF.
Our laboratorys work shows that as individuals age, the brain believes and processes information in a different way. In addition, weve observed changes in time in how peoples bodies move and how people find out brand-new motor abilities. Numerous decades of work have actually shown that older grownups have a harder time processing and manipulating information– such as updating a psychological grocery list– however they generally maintain their understanding of realities and vocabulary. With regard to motor skills, we know that older adults still learn, however they do so more gradually then young people.
When it comes to brain structure, we usually see a decline in the size of the brain in adults over age 65. Differences can be seen across many regions of the brain.
As life span has increased in the past decades, more people are reaching older age. While the objective is for all to live healthy and long lives, even in the best-case circumstance where one ages without illness or disability, older the adult years induces changes in how we think and move.
Knowing how all of these puzzle pieces fit together will help us unwind the secrets of aging so that we can help improve lifestyle and function for aging individuals. And now, in the context of COVID-19, it will help us understand the degree to which the brain might recuperate after health problem too.
Written by Jessica Bernard, Associate Professor, Texas A&M University.
This short article was first published in The Conversation.