A latest COVID-related study has unraveled the mystery behind the persistence of Long COVID symptoms among patients afflicted with the disease. The study notes that the ‘BBB disruption is evident during acute infection and in patients with long COVID with cognitive impairment, commonly referred to as COVID-19 brain fog’.
Researchers at Trinity College Dublin and FutureNeuro have discovered that leaky blood vessels in brain are partially responsible for brain fog in Long COVID. The researchers analysed more than 200 patients hospitalised with COVID-19 or other symptoms associated with it and compared the results with 60 people without the infection. The comparison highlighted elevated levels of four brain injury biomarkers among COVID-infected people, a key sign of biological change. The study was published in Nature Neuroscience on February 22, 2024.
“Our study shows that markers of brain injury are present in the blood months after COVID-19, and particularly in those who have had a COVID-19-induced brain complication,” neuroscientist Benedict Michael from the University of Liverpool in the UK was quoted as saying by Science Alert.
The researchers used contrast-enhanced magnetic resonance imaging to show BBB disruption in patients with long COVID-associated brain fog. “Our data suggests sustained systemic inflammation and persistent localized BBB dysfunction is a key feature of brain fog associated with long COVID,” the study noted. Though how it happens remains unclear.
It has been more than two years since the dreaded COVID-19 wreaked havoc in the world, and though the virus is comparatively far less virulent, it is still very much active. As per the WHO data, till February 4, 2024, the cumulative figure of COVID cases in the world was 774,593,066. However, it is the long COVID “brain fog” that has kept doctors perplexed.
COVID-19 Brain Fog
The coronavirus first made headlines in November 2019 when a large cluster of people showed symptoms of the disease in Wuhan, China. By early 2020, the whole world was grappling with the disease, which attacked mainly the respiratory systems of patients afflicted by it and was highly contagious. By March, the World Health Organisation had declared it a pandemic.
Since its debut on the global scene, the virus has continuously mutated during the ongoing pandemic, resulting in scores of variants that are different from the original SARS-CoV-2 virus. The latest strain of the virus, JN.1, is a lot closer to the BA.2.86 variant, a lineage of the Omicron variant. And though the JN.1 variant does not cause any severity, it evolves rapidly. Thus far, the most destructive and deadly strain of the SARS-CoV-2 virus has been the Delta variant, especially in India. It not only cost lives but destroyed livelihoods as well.
The most noteworthy aspect of COVID-19, however, was that, despite recovering from the illness, around 30-35% of people continued to experience long Covid symptoms for weeks, months and even years. The symptoms, which can be debilitating, range from chronic pain to shortness of breath, brain fog, intense fatigue and chest pain. According to an article published in yalemedicine.org in October 2023, “severe cases of Long COVID can even affect the body’s organs. But imaging tests don’t always show the origins of those symptoms. And we still don’t know why only some people develop the condition or why others can get it after a mild COVID infection.”
Blood-Brain Barrier Disruption
The Blood-Brain Barrier is a protective layer lining the inner surfaces of the blood vessels inside the brain and forms a key part of the brain and the nervous system. It filters germs and other harmful substances that can harm the brain and controls the entry and exit of the various compounds required and produced by the body.
The National Library of Medicine defines the working of the BBB thus: The blood–brain barrier allows blood vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and also protects the neural tissue from toxins and pathogens, and alterations of these barrier properties are an important component of pathology and progression of different neurological diseases.
New Way to Study Long COVID
“For the first time, we have been able to show that leaky blood vessels in the human brain, in tandem with a hyperactive immune system may be the key drivers of brain fog associated with Long COVID. This is critically important, as understanding the underlying cause of these conditions will allow us to develop targeted therapies for patients in the future,” the head of genetics at Trinity, and PI at FutureNeuro, Matthew Campbell, was quoted by genengnews.com as saying.
The discovery is crucial as it opens doors for further research on the impact of viral infections on the “vasculature integrity”. The study highlights the fact that viral infections might be acting as triggers for a number of neurological conditions such as Long COVID or Multiple Sclerosis etc.
For more COVID-19 related information, click here.
