COVID-19 Affects Cognition and Dementia

With the spread of SARS-CoV-2, it has emerged that risk factors for COVID-19 overlap with those of Alzheimer disease (AD) and that people recovering from COVID-19 have accelerated dementia symptoms and pathology. This puts older individuals and those with preexisting AD or mild cognitive impairment at a greater risk from COVID-19 with consequent higher mortality. 

Individuals over age 60 have experienced persistent cognitive impairment after recovering from SARS-CoV-2 infections. In a study of 233 individuals infected with SARS-CoV-2, 45% had no cognitive symptoms. Memory-only impairment (MOI) and multidomain impairment (MDI) were seen in 21% and 34%, respectively. Those with MDI had severe alterations in attention, executive function, semantic memory, short-term memory, and naming.

Another study examined brain health biomarkers in individuals with SARS-CoV-2 infection. Individuals who had COVID-19 with neurologic symptoms had elevated neurofilament light (NfL; P=.0003), glial fibrillary acid protein (GFAP; P<.01), and total-tau (P=.04) and phosphorylated-tau (P=.0141) levels compared with people who had COVID-19 without neurologic symptoms. 

In another study of 32 individuals who did not have an overnight stay in a hospital with an assessment 2 months after recovering from COVID-19, 56.2% showed signs of cognitive decline on the Montreal Cognitive Assessment (MoCA). The cause may be associated with oxygen saturation (SpO₂) and physical condition which may indicate overlap with postCOVID-19 fatigue. The MoCA score correlated with age (P=.003), waist circumference (P=.028) waist-to-hip ratio (P=.042) and SpO₂ during 6-minute walk test (6MWT) (1st, 4th and 6th minute; P<.05). Middle latency response (MLR) indicated that after adjusting for age and gender, SpO₂ at the 6th minute of the 6MWT was independently associated with MoCA score (P =.001). More research is needed to understand the reasons for these associations.

“These new data point to disturbing trends showing COVID-19 infections leading to lasting cognitive impairment and even Alzheimer symptoms,” said Heather M. Snyder, PhD, Alzheimer Association vice president of Medical and Scientific Relations. “With more than 180 million cases and nearly 4 million deaths worldwide, COVID-19 has devastated the entire world. It is imperative that we continue to study what this virus is doing to our body and brain. The Alzheimer Association and its partners are leading, but more research is needed.”