People who carry two faulty copies of the APOE gene – linked to dementia – are at twice the risk of developing severe Covid-19, scientists have reported.
Professor David Melzer and his team at the University of Exeter, UK, worked on the project with collaborators at the University of Connecticut, USA.
They analysed information from the UK Biobank from genetically European ancestry participants aged 48 to 86 years who had lab-confirmed Covid-19. This showed that pre-existing dementia is linked to a more than three-fold higher risk of severe Covid-19.
The researchers report that in another UK study of 16,749 patients hospitalised for Covid-19, dementia was associated with higher mortality.
“Additionally, impaired consciousness, including delirium, is common in severe cases,” they write in yesterday’s (16 May) Journal of Gerontology: Medical Sciences.
In their own study, they found that: “The ApoE e4 genotype is associated with both dementia and delirium, with the e4e4 genotype [two faulty copies] associated with a 14-fold increase in risk of Alzheimer’s disease, compared to the common e3e3 genotype, in populations with European ancestries.”
The authors add that one in 36 people of European ancestry has two faulty copies of this gene.
Professor David Melzer said: "Several studies have now shown that people with dementia are at high risk of developing severe Covid-19. This study suggests that this high risk may not simply be due to the effects of dementia, advancing age or frailty, or exposure to the virus in care homes.
"The effect could be partly due to this underlying genetic change, which puts them at risk for both Covid-19 and dementia."
Kuo, C-L. et al. APOE e4 genotype predicts severe Covid-19 in the UK Biobank community cohort. Journal of Gerontology: Medical Sciences 26 May 2020; doi: 10.1093/gerona/glaa131
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