Dementia genotype may increase COVID-19 vulnerability

A new study suggests that the risk of severe COVID-19 may be increased if a person has a genotype that is associated with dementia, as well as other cardiovascular issues.

Older adult wearing mask
Gene combinations associated with dementia risk may also influence COVID-19 severity.

The study, published as a letter to the editor in The Journals of Gerontology, Series A, indicates that having the genetic component of dementia might increase the risk of developing a more severe case of COVID-19.

Dementia is a name for various progressive neurological diseases that typically affect a person’s memory or cognitive ability. The most common type of dementia is Alzheimer’s disease.

According to the World Health Organization (WHO), around 50 million people worldwide have dementia. It typically affects older adults, but some forms can develop earlier on.

There is an association between Alzheimer’s disease and various cardiovascular issues. This is one reason why people with dementia may be at more risk of COVID-19, since cardiovascular issues are likely to increase the chances of a person dying if they contract COVID-19.

In addition, a person with dementia is more likely to be living in a care home, and these facilities have been key sites for the spread of the disease.

Also, because of dementia’s effects on cognitive function, a person with dementia may be less likely to follow safety protocols and so have more risk of exposure to the virus.

Adding to these known risk factors, the present research suggests that the genetic conditions that can contribute to dementia may increase a person’s chances of developing a severe case of COVID-19.

Large sample size

In the present study, scientists from the University of Exeter Medical School, in the United Kingdom, and the University of Connecticut School of Medicine, in the United States, analyzed data from the UK Biobank, a repository of health information from over 500,000 people living in the U.K., who are currently aged between 48 and 86 years old.

The UK Biobank now includes data from COVID-19 laboratory results that came through between March 16 and April 26. In general, during this period, only people who were hospitalized received COVID-19 testing, indicating that the data is from people who experienced more severe infections.

The scientists looked at data from participants with European ancestry, focusing on the gene APOE, as having two copies of the variant e4e4 is known to increase the risk of Alzheimer’s disease by 14 times, as well as the risk of heart disease.

Genetics affects severity?

The scientists first looked at the rate of the e4e4 genotype in the overall sample, identifying it in 2.36% of the participants. However, when they restricted the sample to only include people who had tested positive for COVID-19, they found that 5.95% of people had the faulty gene.

Their analysis indicated that the risk of severe COVID-19 is doubled in people with two copies of the variant e4e4, compared with people who have the more common genotype APOE e3e3.

Significantly, this risk was present whether or not a person had a diagnosis of dementia, suggesting that an underlying genetic component may be at play.

For study co-author Chia-Ling Kuo, Ph.D., “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 aging 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 60s.”

According to Prof. David Melzer, who led the team, “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.”

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