Severe Covid infections can cause immune reactions that damage nerve cells in the brain, causing memory problems and confusion, and potentially raising the risk of long-term health issues, research suggests. Scientists at King’s College London found that a wayward immune response to the virus increased the death rate of neurons and had a “profound” impact on regeneration in the hippocampus region of the brain, which is crucial for learning and memory.
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“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.”
Carmine Pariante, a professor of biological psychiatry at KCL’s Institute of Psychiatry, and senior author on the study
The researchers analysed blood from 36 Covid patients admitted to Guy’s and St Thomas’ NHS Foundation Trust in London in the first wave of the pandemic. They found that levels of a protein called IL-6, which immune cells release as a rallying call for other immune cells, were more than 15 times higher than normal in infected individuals.
“What they’ve been able to show is that increased inflammation has a direct effect on brain cells which we know are linked to delirium and memory problems. The reduction in repair mechanisms and regeneration might begin to explain why people with delirium can have longer term cognitive problems.”
Dr Thomas Jackson, a geriatrician who studies delirium and inflammation at the University of Birmingham
ME Association Comment
“These are some interesting and important preliminary findings from a Kings College research study that has looked at immune system responses to Covid in a small group of people who were treated in hospital.
“The findings link in with the very large Oxford study that is using electronic health records from several million people who had Covid to find out whether there is an increased risk of developing degenerative neurological disease and/or psychiatric disease over a long period of time.
“Preliminary results from the Oxford study indicate that there appears to be a small but significant increased risk of developing serious neurological diseases such as dementia and Parkinson’s disease two years later.
“The suggestion that raised levels of an immune system chemical called interleukin 6 (IL-6), which is produced in response to an infection, is the main factor responsible for cognitive dysfunction (and even delirium) in the Kings College study could also link in with the fact that this sort of immune system activation has been found in ME/CFS.
“It is also interesting to note that changes in hippocampal volume have been reported in ME/CFS and linked to cognitive dysfunction.
“Cognitive dysfunction/brain fog is, of course, very common and disabling in both ME/CFS and Long Covid, and we don’t currently have a satisfactory explanation as to why it occurs in either condition.
“But these findings certainly add support to the possibility that an on-going overactive immune system response could be involved. So further research in this direction is warranted in both ME/CFS and Long Covid.”
Dr Charles Shepherd, Trustee and Hon. Medical Adviser to the ME Association
The ME Association has a recently updated information leaflet covering all aspects of cognitive dysfunction in ME/CFS:
Cognitive Dysfunction – Brain Fog
Dr Charles Shepherd,
Trustee and Hon. Medical Adviser to the ME Association.
Member of the 2018-2021 NICE Guideline Committee.
Member of the 2002 Independent Working Group on ME/CFS.
