The risk of an Alzheimer’s disease diagnosis nearly doubled for older adults in the year following a bout with COVID-19, a new study of 6.2 million adults finds.
If this increase in new Alzheimer’s diagnoses continues, the resulting wave of disease would further strain already limited long-term care resources, investigators said. Notably, nursing home stay status was not controlled for. While it is a risk factor for COVID-19, it is not a known risk factor for Alzheimer’s disease, first author Rong Xu, PhD, told McKnight’s Clinical Daily.
In the study, investigators from Case Western Reserve University in Cleveland compared data on a U.S. population aged 65 years and older with and without COVID-19. After controlling for Alzheimer’s factors, they found that the various COVID-19 cohort slices had at least a 50% higher relative risk of being diagnosed with Alzheimer’s within one year.
Older women most at risk
Results showed the risk of developing Alzheimer’s was the highest in people aged 85 years and older, and women as a group were at particularly high risk.
“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 co-author Pamela Davis, MD, PhD, in a statement.
“Since infection with SARS-CoV2 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,” she added.
Study participants received medical treatment between February 2020 and May 2021. They had no prior diagnosis of Alzheimer’s disease. The researchers controlled for factors such as actual age, other demographics, adverse socioeconomic determinants of health and comorbidities including hypertension, cardiovascular diseases and diabetes.
Clinicians have been optimistic that reducing general risk factors such as hypertension and heart disease would begin to make a dent in Alzheimer’s prevalence, Davis said. COVID, however, appears to be a big neutralizer.
“Now, so many people in the US 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 said.
An estimated 6.5 million Americans aged 65 years and older are living with Alzheimer’s in 2022, according to the Alzheimer’s Association. The group’s 2020 Alzheimer’s Disease Facts and Figures report noted that 48% percent of nursing home residents are living with Alzheimer’s or other dementias.
Study limitations include potential inaccuracy in Alzheimer’s disease diagnosis, although this should not affect the relative risk analyses since all cohorts came from the same dataset, the researchers wrote. The investigators are planning longer-term follow-up and will study COVID-19’s impact on other types of dementia, and which subpopulations may be more vulnerable, they said.Full findings were published in the Journal of Alzheimer’s Disease.
