COVID-19 can cause “significant abnormalities” in the brains of patients for up to six months after they recover from the disease, researchers have found.
Using a special type of magnetic resonance imaging (MRI) scan on a small number of patients, scientists found differences in the brains of recovered COVID patients - specifically in the frontal lobe and brainstem - compared to those of a healthy control group.
The affected regions are linked with issues commonly reported in long-COVID patients, such as fatigue, insomnia, anxiety, and other cognitive problems, the researchers said.
For the study, which will be presented next week at the annual meeting of the Radiological Society of North America, researchers used susceptibility-weighted imaging to analyse the effects that COVID-19 has on the brain.
Magnetic susceptibility shows how certain materials - such as blood, iron, or calcium - become magnetised in a magnetic field, allowing for the detection and monitoring of neurological conditions including microbleeds, vascular malformations, brain tumours and stroke.
Previous studies have not focused on how this magnetic susceptibility might change following coronavirus infection, said study co-author Sapna Mishra, a PhD candidate at the Indian Institute of Technology in Delhi.
"Our study highlights this new aspect of the neurological effects of COVID-19 and reports significant abnormalities in COVID survivors," she said in a statement.
Symptoms of long COVID
The researchers analysed the MRI results of 46 patients who had recovered from COVID, and 30 healthy control patients.
The imaging was done within six months of recovery, and among the COVID patients, the most commonly reported symptoms were fatigue, trouble sleeping, lack of attention and memory issues - all of which are potential symptoms of long COVID.
The results showed the COVID patients had “significantly higher susceptibility values” on the frontal lobe and brainstem.
The researchers also spotted significant differences in the right ventral diencephalon region of the brain stem, a region associated with many crucial bodily functions such as regulation of hormones and the circadian rhythm.
"This study points to serious long-term complications that may be caused by the coronavirus, even months after recovery from the infection," Mishra said.
The researchers are continuing a longer-term study to find out if these abnormalities will persist over a longer time frame.
Emerging long-term effects
It’s estimated that millions of Europeans are currently suffering from long COVID, and various studies have started to reveal potential long-term effects.
The neurological symptoms associated with long COVID include difficulty thinking or concentrating, headache, sleep problems, lightheadedness, pins-and-needles sensation, change in smell or taste, and depression or anxiety.
Previous studies have found COVID-19 can cause the brain to shrink, reducing grey matter in regions that control emotion and memory.
An Oxford University study also found it can damage areas that control the sense of smell.
The researchers behind that study said the effects could be seen in people who had not been hospitalised, and longer-term investigation was needed to see if the impacts could be reversed.
The study, which was peer-reviewed and published in the journal Nature in March, looked at brain changes in 785 participants aged 51 to 81.
Other studies have confirmed the potential impact on cognitive functions due to COVID-19 infection.
One found a severe case of infection could cause cognitive damage equivalent to 20 years of ageing.