People aged 65 and over had a significantly higher risk of developing dementia and Alzheimer’s disease within a year of contracting COVID-19, according to a huge new study of 6 million people. When compared to the control group, there was a 50-80 percent increased risk of developing the neurological disease in people infected with COVID-19, highlighting the current and potential future implications the virus may have on the older populations.
Previous research had implicated COVID-19 in the development of neurological disease. It had been reported that it was inflammation that was causing damage to the brains of infected patients, but autopsy studies highlighted SARS-CoV-2 particles within brain neurons, suggesting the virus invades cells directly.
“The factors that play into the development of Alzheimer's disease have been poorly understood, but two pieces considered important are prior infections, especially viral infections, and inflammation," said Pamela Davis, Distinguished University Professor and the study's coauthor, in a statement.
"Since infection with SARS-CoV-2 has been associated with central nervous system abnormalities including inflammation, we wanted to test whether, even in the short term, COVID could lead to increased diagnoses.”
COVID-19 and Alzheimer's disease
In this retrospective study, researchers from the US took a large sample of over 6 million patients with no history of Alzheimer’s disease. They divided them into a control group that didn’t contract COVID-19, and an experimental group that did. The groups came from diverse racial and socio-economic backgrounds, attempting to limit confounding variables.
The researchers discovered that in the COVID-19 group, the cohort saw a nearly doubled risk of developing Alzheimer’s disease within one year, with the most dramatic increase in women of age 85 and over.
While the results are damning, the researchers stress they do not yet know how COVID-19 could be involved in the onset of Alzheimer’s – however, the findings do paint a possibly grim future for Alzheimer’s diagnoses.
"If this increase in new diagnoses of Alzheimer's disease is sustained, the wave of patients with a disease currently without a cure will be substantial, and could further strain our long-term care resources," Davis continued.
"Alzheimer's disease is a serious and challenging disease, and we thought we had turned some of the tide on it by reducing general risk factors such as hypertension, heart disease, obesity and a sedentary lifestyle. Now, so many people in the U.S. have had COVID and the long-term consequences of COVID are still emerging. It is important to continue to monitor the impact of this disease on future disability."
The research was published in the Journal of Alzheimer’s Disease.