We know that the elderly and those with underlying health conditions have a higher risk for severe disease and death from the coronavirus. And dementia appears to be particularly bad. Those with dementia are three times more likely to suffer from severe COVID-19.

The question is why. Residents of assisted-living and nursing home facilities have accounted for roughly half of the COVID-19 deaths in the US, according to data from the Kaiser Family Foundation. About half of the residents of these facilities suffer from dementia.

A new study in The Journals of Gerontology shows the risk of serious illness from COVID-19 among people with dementia appears to have a genetic link. Researchers found that a variant of the dementia gene ‘APOE’ could play a large role.

Each of us normally inherits two copies, one from each parent, either ApoE3 or e4. Among individuals of European ancestry, most have two copies of the e3 variant. But just over two percent have two copies of the faulty e4, which puts you at significantly higher risk of dementia.

In this new study, patients with two e4 variants had more than double the risk of severe COVID-19 than those with two e3 variants.

Now scientists will try to figure out how this gene causes vulnerability to COVID-19, hopefully leading to new treatments in the future.