Dementia the strongest risk factor for infection with COVID-19 in older people

Reviewed by Emily Henderson, B.Sc.Mar 8 2023

In 2020, the first year of the COVID-19 pandemic, dementia was the dominant risk factor for the disease among residents of Swedish nursing homes. This elevated risk applied to both getting infected with and dying of COVID-19, a University of Gothenburg study shows.

The purpose of the study, now published in The American Journal of Geriatric Psychiatry, was to analyze risk factors for infection with COVID-19 and dying of the disease respectively, for older people living in Swedish nursing homes.

The data comprised data of 82,488 people in total, making up 99 percent of the entire group nationwide. The study period was the whole pandemic year of 2020, a year comprising pandemic waves both in the spring and in the runup to Christmas, while mass vaccinations against COVID-19 were not rolled out until close to year-end.

The study results indicate that several factors boosted the risks of, first, getting infected with the disease and, second, dying of it. After adjustments for comorbidity and sociodemographic factors such as sex, age, and education, seven independent risk factors emerged: advanced age, male sex, dementia, cardiovascular disease, lung and kidney disease, high blood pressure (hypertension), and diabetes.

Early-onset dementia the strongest risk factor

Of the above seven factors, the most influential throughout the year and during the different waves was dementia. The strongest association between dementia and mortality from verified COVID-19 infection was found in the 65-75 age group.

So those at the highest risk of both getting infected with and dying of COVID-19 were the people with early onset of dementia. That might be due to the features of the illness, with its more rapid progression."

Jenna Najar, study's first and corresponding author

Najar conducts research in neuropsychiatric epidemiology both at the Institute of Neuroscience and Physiology and in AgeCap, the Centre for Ageing and Health at the University of Gothenburg.

The other authors in the study are affiliated with the Department of Political Science: Associate Professor (docent) Rasmus Broms, Professor Carl Dahlström, and Associate Professor (docent) Marina Nistotskaya.

More precisely targeted strategies in new pandemics

Their work has contributed to the Swedish Corona Commission, within the framework of the Swedish Register-based Research Program on COVID-19 (SWECOV) organized by Stockholm University.

Jenna Najar is also a medical doctor, resident in psychiatry at the Psychiatry, Cognition and Old Age Psychiatry Outpatient Clinic at Sahlgrenska University Hospital.

"The results of the study provide key information about which factors can be linked to negative outcomes — getting infected with and dying from COVID-19. This knowledge may enable us to implement risk-specific strategies in future local epidemics, or perhaps in new pandemics," she concludes.