Faulty gene linked to dementia doubles risk of infection

Having a faulty gene linked to dementia doubles the risk of developing severe Covid-19, according to a large-scale study.

Faulty gene linked to dementia doubles serious infection risk

Researchers at the University of Exeter Medical School and the University of Connecticut analysed data from the UK Biobank, and found high risk of severe coronavirus infection among European ancestry participants who carry two faulty copies of the APOE gene (termed e4e4).

One in 36 people of European ancestry have two faulty copies of this gene, and this is known to increase risks of Alzheimer’s disease up to 14-fold and also increases risks of heart disease.

Now, the research team has found that carrying these gene mutations doubles the risks of Covid-19 - even in people whohad not developed these diseases.

The team has previously found that people with dementia are three times more likely to get severe Covid-19, yet they are not one of the groups advised to shield on health grounds.

Part of the increased risk effect may have been exposure to the high prevalence of the virus in care homes.

However, the new study, published in the Journal of Gerontology: Medical Sciences, indicates that a genetic component may also be at play.

The team found that people with the APOE e4e4 genotype were at double the risk of developing severe Covid-19, compared to those with the common e3e3 form of the APOE gene. The team used data from the UK Biobank study, which collects health andgenetic data on 500,000 people.Co-author Dr Chia-Ling Kuo, of the University of Connecticut, said: “This is an exciting result because we might now be able to pinpoint how this faulty gene causes vulnerability to Covid-19.

“This could lead to new ideas for treatments.

“It’s also important because it shows again that increasing disease risks that appear inevitable with ageing might actually be due to specific biological differences, which could help us understand why some people stay active to age 100 and beyond, while others become disabled and die in their sixties.”

Alzheimer’s Research UK says action is needed to protect people with dementia from Covid-19 – after it’s been revealed that nearly one in five (18 per cent) of all people who have died from the virus also had dementia.

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said: “A previous study from this group of researchers found that dementia was the diagnosis associated with the greatest risk of severe Covid-19 in a group of participants over the age of 65.

“One explanation for people with dementia being more vulnerable to Covid-19 could be high rates of infection in care homes, but this research highlights a potential biological link.

“The study found that people with a key genetic risk factor for Alzheimer’s disease appear to be more likely to test positive for Covid-19, even if they don’t have dementia.

“We don’t yet know how this Alzheimer’s risk gene might make people more susceptible to the virus.

“Despite the large study group, only 37 people with the risk gene tested positive for Covid-19, and we must be careful about the conclusions we draw from such small numbers.

“These findings will need to be followed up with further research to see if this link could present avenues for new treatments.

“This study analysed data from participants with European ancestry so the findings may not be relevant to other groups and it is important for other studies to look into Covid-19 risk for people with a different genetic background.”

Prof John Gallacher, Director of Dementias Platform UK, University of Oxford, said: “This paper provides strong evidence of a link between genetic risk for Alzheimer’s disease and genetic risk for Covid-19.

“This suggests one or more common mechanisms underlying both conditions. A common mechanism would indicate increased risk of Covid-19 in those with Alzheimer’s disease, but not that Alzheimer’s disease itself is a direct cause of Covid-19 susceptibility.

“However, Alzheimer’s disease may be an indirect cause.

“For example, increased frailty in those with Alzheimer’s disease would imply reduced resistance to infection and increased disease severity.

“Increased risk and increased frailty are reasons enough to consider those with dementia to be a high risk group for Covid-19.”