A set of symptoms, which can persist for several months or even years after the disappearance of an acute COVID infection, have been described in the medical literature with increasing frequency since the start of the pandemic. This constellation of findings has been dubbed “long COVID.” The effects of long COVID on the brain, in particular, have certainly made the news, and they have also appeared in the medical literature. So, what is the relationship between the coronavirus (and the vaccine) and neurological long COVID?
Neurological long COVID
In their excellent 2024 paper, Spanish researchers reported on their experience with patients suffering from neuropsychological symptoms and signs that persisted long after the acute COVID-19 infection had subsided. The scientist evaluated more than a hundred patients who had been diagnosed with coronavirus. Eighty of the volunteers still suffered from lingering problems and the other twenty had fully recovered.
Subjects underwent psychological and neurological examinations as well as MRI scans. About half of the patients diagnosed in the Spanish study with long COVID had significant memory problems. About a quarter of them had thinking problems, including language problems (speech fluency), attention problems, and the ability to mentally process any type of intellectual challenge at normal speed (slow cognition or laborious). In 2023, Croatian researchers elucidated the most common clinical aspects of neurological long COVID. Based on an analysis of more than 200 patients, Croatian doctors have determined that long COVID is more common in women than in men. Affected patients often suffer from a multitude of symptoms, which can include headaches, difficulty thinking clearly, loss of sense of smell, numbness, fatigue, dizziness and insomnia.
Long COVID has also changed brain anatomy in many affected patients. The Spanish researchers found that, compared to the twenty patients who had fully recovered from COVID, the eighty who suffered from persistent neurological symptoms had abnormalities on MRI. The white matter (the cables that connect different parts of the central nervous system) of those who suffered for a long time from COVID was disrupted over large areas of the brain. Additionally, MRI revealed that the gray matter (the thinking part of the brain) of a large cohort of neurological long-COVID patients had wasted away in the left posterosuperior temporal gyrus (a part of the brain crucial for understanding language).
Do vaccines protect against neurological long COVID?
The largest study (by far) examining the relationship between vaccination and the development of long COVID was carried out by a multinational group of scientists (American, Japanese and British) in 2023. These researchers evaluated the medical records of more than 600,000 people. Unfortunately, their efforts were not focused on neurological long COVID (most of their long COVID patients only reported fatigue and shortness of breath), but I think the findings can be extrapolated. Scientists have discovered two important facts. First, those who were vaccinated had a significantly lower risk of developing long COVID. Second, for those already suffering from long COVID, additional vaccinations (booster shots) did not cause exacerbation of symptoms.
Can vaccines cause neurological long COVID?
In April 2023, a multinational team of Swiss and German scientists highlighted that, globally, there were already 760 million confirmed cases of COVID-19 and more than 13 billion vaccine doses administered. These researchers recognized the existence of a significant number of people who had received an injection of an mRNA-based vaccine and who subsequently developed a syndrome similar to long COVID. The authors of the manuscript warned the medical establishment against poo-pooing this portion of the affected population by lumping them in with those disparagingly called “anti-vaccines.”
In 2022, Saudi doctors described complications related to COVID-19 vaccines, particularly those that could lead to long-term neurological problems. Their report focused on three broad categories of questions. First, scientists described post-vaccination cerebral venous thrombosis (blood clots in the vessels of the brain), which was often accompanied by a significant incidence of stroke. Secondly, the doctors were confronted with post-vaccination Guillain-Barré syndrome (a potentially progressive paralysis of the legs, arms and diaphragm (respiratory muscles). Finally, the researchers observed several patients suffering from Miller syndrome -Fisher post-vaccination (a disorder in which the immune system attacks the nerves that control facial and eye movements).
A 2023 publication described MRI findings in patients who suffered neurological complications after receiving COVID-19 vaccines. Doctors who have treated patients across Iran have reviewed nearly 90 scientific studies and reported numerous harmful aftereffects of vaccinations in imaging. The most commonly observed brain injuries were related to minor or major strokes. Researchers also observed inflammation (sometimes severely destructive) in large areas of the brain and spine.
You can clearly see that our understanding of neurological long COVID is evolving. We are learning more and more about the causes and symptoms of this dreaded syndrome. The jury is still out on how much benefit or culpability vaccines have in relation to neurological long COVID.
Marc Arginteanu is a neurosurgeon and author of Azazel Public House.