An infectious etiology of Alzheimer’s disease has been postulated for decades and despite supportive evidence, it is still controversial . The increased risk for COVID-19 in people with Alzheimer’s disease and recent recognition of long lasting neurological sequelae of SARS-CoV2 infection in part reflecting inflammatory processes, which are central to Alzheimer’s disease neuropathology, suggest bidirectional relationships. However, whether COVID-19 might trigger new-onset Alzheimer’s disease or accelerate its emergence is unclear.
Pamela Davis, MD, PhD, a professor in the Center for Community Health Integration at Case Western Reserve School of Medicine, and her team,analyzed anonymous electronic health records of 6.2 million adults aged 65 years or older who received medical treatment between February 2020 and May 2021 and had no prior diagnosis of AD. The database includes data on almost 30% of the entire US population.
Overall, there were 410,748 cases of COVID during the study period.
The overall risk for new diagnosis of AD in the COVID-19 cohort was close to double that of those who did not have COVID (0.68% vs 0.35%, respectively).
After propensity-score matching, those who have had COVID-19 had a significantly higher risk for an AD diagnosis compared with those who were not infected (hazard ratio [HR], 1.69).
Risk for AD was elevated in all age groups, regardless of gender or ethnicity. Researchers did not collect data on COVID-19 severity, and the medical codes for long COVID were not published until after the study had ended.
Those with the highest risk were older than 85 years (HR, 1.89) and women (HR, 1.82).
Older adults with COVID-19 were at significantly increased risk for new diagnosis of Alzheimer’s disease with highest risk in people aged ≥85 and in women. Study limitations include potential biases introduced by the observational and retrospective nature of this study and inaccuracy in Alzheimer’s disease diagnosis, which should not substantially affect the relative risk analyses since all cohorts were drawn from the same dataset.
Because this study only showed an association through medical records, we cannot know what the underlying mechanisms driving this association are without more research. If you have had COVID-19, it doesn’t mean you’re going to get dementia. But if you have had COVID-19 and are experiencing long-term symptoms including cognitive difficulties, talk to your doctor.
Wang, Lindsey, Davis, Pamela B. Volkow, Nora D, Berger, Nathan A., Kaelber, David C, Xu, Rong, (July 18, 2022). Association of COVID-19 with New-Onset Alzheimer’s Disease. Journal of Alzheimer’s Disease. Retrieved from :