Study Discovers Connection Between Omicron Infection and Brain Structure Changes in Men

A recent study in the JAMA Network Open journal looked at how people’s brains and health are affected during the severe phase of the COVID-19 Omicron infection.

Here’s what the study found:

Other studies found that, just like with the Delta variant of the virus, getting infected with the Omicron variant causes various symptoms throughout the body, including problems with the nervous system. Symptoms linked to COVID-19 can include things like feeling dizzy, moving slowly, feeling sad or anxious, and having trouble thinking clearly. These symptoms are related to changes in the structure and function of the brain.

But, so far, not much research has been done on people with mild nervous system symptoms during the early stage of an Omicron infection, especially concerning potential damage to the brain’s microstructure after the infection.

About the Study:

At first, 207 men got special scans called magnetic resonance imaging (MRI) between August 28, 2022, and September 18, 2022. But when the researchers looked at the information, they only had data for 98 people. After three months, the researchers checked again, this time with all 61 participants, to get more information about their neuropsychiatric and MRI data and clinical symptoms.

To be part of the study, everyone had to test positive for the SARS-CoV-2 infection using a specific test called nucleic acid test (NAT) in December 2022. When they joined the study, the participants couldn’t have anything in their medical history that would make MRI scans risky, like brain problems, tumors, or endocrine diseases.

The people in the study were split into groups based on whether they got sick with Omicron infection or not, and whether they had a fever or not. They looked at changes in the structure of the brain for these groups. They used a special type of 3D scan, called magnetization-prepared rapid acquisition gradient echo, to measure gray matter and subcutaneous nuclear volume. The results were shown in a special kind of plot called a violin plot. After the brain scans, they did more tests to see how people were feeling and thinking.

During the brain scans, they used different imaging techniques like T1- and T2-weighted imaging, fluid-attenuated inversion recovery imaging, and 3D-MPRAGE. They used a software called FreeSurfer to make sure the images were good quality, fix any motion issues, separate the brain into different parts, match the images, and calculate different brain measurements.

To compare the data, they used Pearson or Spearman correlation analyses based on how the information was spread out. They also adjusted the results to make sure they weren’t getting false findings when comparing multiple things, using something called the false discovery rate (FDR).

What the Study Found:

In this study, there were 61 men who took part, and their average age was around 43 years old. The time between getting infected with Omicron and having their brain scans was about 21.6 days. After getting sick, the scores on a test called Beck Anxiety Inventory (BAI) went up, showing more anxiety. But the scores on another test called Depressive Distress (DES) went down, indicating less sadness.

When they looked at how well people could think and process information, they found that age and whether someone used nicotine had a significant impact, regardless of whether they had a fever or not. Other factors didn’t seem to make a big difference.

After checking in later, the researchers found different outcomes for symptoms related to the nerves, breathing, and digestion. Breathing issues like coughing and difficulty breathing happened quite often and lasted for a while. Not feeling hungry happened a lot and continued for a long time.

Having a fever and reacting slowly were common, but they didn’t last very long. However, after three months, there were notable improvements in fever, myalgia, and coughing.

After people got sick with Omicron infection, the researchers noticed that certain parts of the brain became thinner, like the left precuneus and right lateral occipital region. Also, the size of the right hippocampus compared to the total brain size was smaller during the follow-up after Omicron compared to before.

In the group of people who had a fever, a part of the brain called the right inferior parietal region became shallower compared to those who didn’t have a fever.

When they looked at how thick the left precuneus was, it was connected to scores on a test called Beck Anxiety Inventory (BAI) in a negative way. This means that as thickness decreased, anxiety scores went up. On the other hand, there was a positive connection between the size of the right hippocampus compared to the total brain size and scores on another test called WFT. This means that as the size of the right hippocampus compared to the total brain size increased, WFT scores also went up.

Conclusion

In short, people didn’t have symptoms for a long time after getting Omicron, but the study found changes in the thickness of the brain and the volume of certain parts.

These results help us understand how Omicron affects our emotions and thinking, and how it’s linked to changes in the nervous system. Unlike the Delta variant, which affects the nervous system through the smell nerve and makes parts of the brain smaller, Omicron enters through a different nerve pathway called the terminal nerve pathway. This pathway has something called angiotensin-converting enzyme 2 (ACE2).

This study gives us a foundation for using brain scans early on to find and treat potential long-term problems with the nervous system caused by COVID-19.

Journal reference:

Gray Matter Thickness and Subcortical Nuclear Volume in Men After SARS-CoV-2 Omicron Infection.

JAMA Network Open 6(11). doi:10.1001/jamanetworkopen.2023.45626