COVID-19 May Lead to Persistent Brain Injury Undetected by Routine Tests

Rapid onset of acute COVID-19 symptoms can cause key brain injury markers that even months later persist.

Freepik

COVID-19 not only damages the lungs and respiratory system but can also cause severe harm to the heart, intestines, and nervous system (including the brain). A study in the UK has shown that the brain injury caused by COVID-19 may persist for months after infection.

The study published in the journal Nature Communications in December 2023 revealed that some recovering COVID-19 patients, while appearing healthy in routine blood inflammation tests, exhibited brain injury markers in their blood.

The study analyzed samples from more than 800 hospitalized COVID-19 patients in England and Wales, half of whom had developed new neurological conditions. The researchers measured markers of brain injury in these samples, including antibodies, serum inflammatory proteins (cytokines), and brain (neuroglial) injury proteins.

Story continues below advertisement

The results indicated that during the rapid onset of acute COVID-19 symptoms, the body produces various key inflammatory proteins and brain injury markers. Surprisingly, even months later, brain (neuroglial) injury biomarkers still persist in some COVID-19 patients.

These inflammatory markers are linked to abnormal immune responses during the acute phase of the disease. The researchers believe these markers may play a role in treating COVID-19 and other infections that lead to acute brain dysfunction.

Professor Benedict Michael, principal investigator and director of the University of Liverpool’s Infection Neuroscience Laboratory and honorary consultant neurologist at The Walton Centre, stated in a press release that during the COVID-19 pandemic, neurological complications became apparent in a “significant proportion of hospitalized patients,” including those with mild COVID-19 infections. While some neurological symptoms, such as headaches and muscle aches (myalgia), were often mild, he went on to say, the emergence of more severe and potentially life-altering neurological complications became evident. These complications include encephalitis (brain inflammation), seizures, and stroke.

Despite the resolution of inflammatory responses in the blood, markers of brain injury persisted in the blood several months after COVID-19 infection, particularly in patients who experienced brain complications such as inflammation and stroke, Mr. Micheal explained. This implies the possibility of ongoing inflammation and damage within the brain that are undetected by blood tests, he added.

Story continues below advertisement

Professor Leonie Taams, head of the School of Immunology & Microbial Sciences mentioned that by combining neurology, immunology, and infection research, they were able to unveil some biomarkers associated with COVID-19-related neurological complications. This aids in laying the foundation for elucidating the potential mechanisms behind these complications, she said.

Even Mild Cases of COVID-19 Infection Can Cause Brain Injury

In 2022, researchers from the University of Oxford published a paper in the journal Nature, demonstrating that even mild cases of COVID-19 infection can lead to brain atrophy. After analyzing data from 785 patients, aged 51 to 81, in the UK database, they found a significant reduction in gray matter thickness in the parahippocampal gyrus and orbitofrontal cortex (located in the lower frontal lobe, a primary neural mechanism for human emotion). Additionally, the brain’s overall size also decreased, with an average shrinkage of 0.7 percent in brain regions associated with olfaction (smell).

Professor Gwenaëlle Douaud, the lead author of the study, stated in a press release: “Despite the infection being mild for 96% of our participants, we saw a greater loss of grey matter volume, and greater tissue damage in the infected participants, on average 4.5 months after infection. They also showed greater decline in their mental abilities to perform complex tasks, and this mental worsening was partly related to these brain abnormalities.”

According to the Johns Hopkins Encephalitis Center, encephalitis (brain inflammation) can lead to cerebral swelling, resulting in symptoms such as headaches, neck stiffness, sensitivity to light, mental confusion, and seizures. In the past decade alone, more than 250,000 patients in the United States have been diagnosed with encephalitis, and the condition is more prevalent in younger individuals.

Encephalitis can lead to various symptoms, including confusion, personality changes, memory loss, seizures, movement disorders, and alterations in vision or hearing.

Therefore, if an individual exhibits the aforementioned symptoms, seeking prompt medical attention is crucial to determine the presence of a severe brain condition. In such cases, they should follow medical advice and undergo active treatment.