Severe covid infections can harm key brain functions, finds study

Covid infections can cause damage to essential brain functions that regulate memory and thought processes, according to new research.

Researchers from King’s College London have shown that when brain cells are directly exposed to blood taken from Covid-19 patients with delirium, there is an increase in cell death and a decrease in the generation of new brain cells.

Previous research indicates that 20 to 30 per cent of Covid-19 patients will develop neurological symptoms such as delirium.

Delirium is a state of mental confusion that can happen if you become medically unwell and is associated with adverse outcomes, including prolonged hospitalisation and death.

This study provides insight into the general effects of Covid-19 infection on the brain.

Researchers took the cells from the hippocampus — an area of the brain linked to cognitive, memory and learning skills — and assessed how they were affected by contact with the serum from infected patients.

The findings published in Molecular Psychiatry could help inform potential treatments to reduce symptoms of confusion, disorientation and memory deficits in Covid-19 patients.  

‘More and more, research is indicating that there is a neurological element to severe Covid-19 infection, but we have little understanding about what happens in the brain to produce these symptoms,’ said Dr Alessandra Borsini, first author of the study.

This is the first research to use blood samples from Covid-19 patients experiencing delirium to investigate how the infection impacts brain functions, including memory and thought processes.

‘We have found that there is a profound reduction in the generation of new brain cells and an increase in cell death, and these are likely mechanisms behind delirium, and possibly other neurological symptoms, in Covid-19 patients,’

Although the respiratory symptoms of Covid-19 are well recognised, the cellular and molecular mechanisms to explain delirium and other neurological symptoms are not well understood.

The development of neurological symptoms in Covid-19 patients is likely to involve an overactive immune response, called the cytokine storm, with an excessive production of multiple inflammatory proteins.

Once produced by the immune cells in the body in response to the infection, these cytokines can then move from the blood to the brain and directly affect brain mechanisms. However, which cytokines are directly relevant to the development of neurological symptoms is currently unknown.

The study collected serum samples from 36 patients admitted to Guy’s and St Thomas’ NHS Foundation Trust, in London, during the first wave of the Covid-19 pandemic in the UK.

Half of these patients were experiencing delirium symptoms whilst the other half did not present with these symptoms at the time of hospital admission. 

Researchers treated cells from the hippocampus directly with the serum samples and observed the impacts on cell generation and death, as well as on the levels of different cytokines.  

Results showed that treatment with serum taken from Covid-19 patients with delirium increased cell death and decreased the generation of new brain cells.

‘These neurological symptoms are very concerning for patients and their families, and the hope is that our research can help identify which treatments would be most appropriate to lessen or prevent these symptoms,’ said Professor Carmine Pariante, another author of the study.

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