Study links long-term impact of Covid-19 on the ageing brain

A recent study has revealed a potential link between Covid-19 and neurological symptoms, such as brain fog, and has raised concerns about the long-term consequences for older people.

Research conducted by scientists at Macquarie University uncovered that the SARS-CoV-2 virus could fuse brain cells so they would either malfunction or stop working altogether.

Macquarie University's Professor Lars Ittner said it could explain common neurological symptoms in Covid patients, including brain fog, headaches, and loss of taste and smell.

"If this is an underlying mechanism of the neurological symptoms we see, it could have a much longer and more serious impact on brain function," professor Ittner said.

Older people are more vulnerable to severe illness, premature death and comorbidities following a Covid infection, especially if they have preexisting conditions like dementia or epilepsy.

Common neurological symptoms among older people include cognitive impairments, fatigue, brain fog, headaches, balance issues, sleep disturbances, and loss of smell and taste.

Professor IIttner said the research could explain why older adults may be more susceptible to neurological symptoms and persistent cognitive issues after a Covid infection.

"While some viral brain infections are fatal and others cause inflammation, this study highlights another outcome where brain cells fuse, potentially leading to brain dysfunction," he said.

The study, published in the journal Science Advances on June 7, was a collaboration between scientists at Macquarie University, the Queensland Brain Institute, the University of Queensland and the University of Helsinki.

Using miniature brain models known as 'mini-brains,' the researchers simulated complex human neuronal networks closely resembling real human brains. 

These mini-brains were infected with various viruses, including the SARS-CoV-2 virus, and compared with non-infected samples.

"This technique provides valuable insights into the long-term neurological symptoms observed in Covid patients," professor Ittner said.

The fusion of brain cells was found to be caused by a specific viral protein called a fusogen, which enabled the virus to enter and infect brain cells. 

This fusion process occurs gradually, resulting in the formation of large clusters of merged cells.

Through Ca2+ imaging, the researchers saw that this fusion significantly disrupted the normal activity of neurons. 

Professor IIttner said that fused brain cells could also act as a hiding place for the virus and evade the immune system's detection. 

"The continuing presence of the virus in the brain raises concerns about the potential for long-term neurological complications in older people," he said.

The research team has initiated a program to investigate the impact of Covid on the brain and its potential connection to the progression, outcome, and onset of dementia.

Studies have suggested that Covid infection can accelerate the structural and functional brain deterioration in all types of dementia.

Covid could also increase the risk of someone developing the disease, according to a recent Lancet report.

They found that after two years, 4.5 per cent of people over 65 who had had Covid were diagnosed with dementia, compared to a diagnosis rate of 3.3 per cent in the control group.

Professor Ittner said the team was developing candidate drug molecules designed to target the virus and how it could lead to neurological symptoms during and post-Covid infection. 

"The molecules show promise in slowing down the virus's replication and alleviating symptoms like brain fog and headaches," Professor IIttner said.

"I'm optimistic that the medication could enter the market sooner rather than later."

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