Some form of brain injury could be behind the symptoms reported by those with long COVID, according to a new study, and adapting tests and treatments to match could aid progress in tackling the condition.
Analyzing 203 patients hospitalized with COVID-19 or its associated symptoms, and comparing the results with 60 people without the infection, researchers noticed elevated levels of four brain injury biomarkers – key signs of biological change – in those infected with COVID-19.
What's more, two of those signs of brain injury persisted into the recovery phase, suggesting that they continue even after the COVID-19 infection has gone. Levels of these two biomarkers were even higher for people who also experienced neurological complications with COVID-19.
"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," says neuroscientist Benedict Michael from the University of Liverpool in the UK.
"This suggests the possibility of ongoing inflammation and injury inside the brain itself which may not be detected by blood tests for inflammation."
These brain complications associated with COVID-19 have ranged from mild (headaches) to potentially life-threatening (seizures, stroke, and encephalitis). As previous research has shown, the consequences can be long-lasting.
Michael and team think that abnormal responses by the body's immune system could be causing the signs of injury they're seeing. If we can find out more about these responses and how they're triggered, new treatments could be developed.
It's now clear that COVID-19 plays some role in impacting the nervous system, and in some cases this impact can continue for an extended period. This new study shows that the effects can be similar to brain injuries.
"The clinical characteristics of our participant cohorts, and the elevation in brain injury markers, provide evidence of both acute and ongoing neurological injury," write the researchers in their published paper.
The researchers are already hard at work following up on their study, looking at how the damage caused by COVID-19 and the associated inflammation might lead to cognitive problems and mental health issues further down the line.
It's thought that tens of millions of people are now living with long COVID in some form, and yet it's still not a condition that we know all that much about. Studies continue to try to spot patterns in its prevalence, which should eventually provide more clues as to how to combat it.
"This work may help set the stage for elucidating the possible underlying mechanisms of these complications," says immunologist Leonie Taams, from King's College London in the UK.
The research has been published in Nature Communications.