Older adults who have had COVID-19 are 50-80% more likely to develop Alzheimer's within a year than those who have not had COVID-19. The corresponding study was published in the Journal of Alzheimer's Disease.
Whether or not Alzheimer's disease has an infectious origin has been a topic of debate for decades. Although evidence suggests that those with the condition have an increased risk of COVID-19 and that SARS-CoV-2 infection affects neurological processes, whether COVID-19 might trigger Alzheimer's remains unclear.
In the current study, researchers analyzed anonymous healthcare records from over 6 million adults aged 65 years and above who had medical encounters between 2020 and 2021. Altogether, around 400,000 people were recorded to have contracted COVID-19, whereas 5.8 million were in the non-infected group.
After analyzing the results, the researchers found that those who had contracted COVD-19 were 50%- 80% more likely than those who did not contract COVID-19 to develop Alzheimer's disease within a year. They noted that women and those aged 85 and older were at the highest risk.
Whereas 0.68% of people in the COVID-19 group developed Alzheimer's within a year, the same was true for 0.47% of those in the non-COVID group. Meanwhile, among those aged 85 and older, 2.01% developed Alzheimer's within a year of having COVID-19, whereas the same was true for 1.33% of those in the non-COVID group.
"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," said co-author of the study, Pamela Davis, Distinguished University Professor and The Arline H. and Curtis F. Garvin Research Professor at the Case Western Reserve School of Medicine.
"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," she noted.
The researchers plan to continue studying the effects of COVID-19 on Alzheimer's disease and other neurodegenerative conditions. They also intend to study the potential of repurposing FDA-approved drugs to treat COVID-19's long-term effects.