COVID-19 Infection Linked to Increased Cognitive Risk, Including Alzheimer’s

Presentations at the recent Alzheimer’s Association International Conference raise the specter of long-term neuropsychiatric effects from COVID-19. Those include loss of smell and taste, as well as cognitive and attention deficits. In the worst case, the infection appears to speed up Alzheimer’s disease and pathology. Here is more information.

DENVER – Alarming new research presented at the recent Alzheimer's Association International Conference (AAIC) 2021 reports associations between COVID-19 and persistent cognitive deficits.

That includes the acceleration of Alzheimer’s disease pathology and symptoms, the organization warns.

In a press release, the Alzheimer’s Association points to short- and/or long-term neuropsychiatric symptoms reported by patients infected with SARS-CoV2. Those include loss of smell and taste, and cognitive and attention deficits commonly called "brain fog."

An international consortium is collecting and evaluating information on how COVID-19 affects the central nervous system over the long term. Key findings presented at AAIC 2021 suggest that biological markers of brain injury, neuroinflammation and Alzheimer's are strongly linked with neurological symptoms in COVID-19 patients. In fact, researchers note that those suffering cognitive decline post-COVID-19 infection also were more likely to have low blood oxygen following brief physical exertion and overall poor physical condition.

"These new data point to disturbing trends showing COVID-19 infections leading to lasting cognitive impairment and even Alzheimer's symptoms," said Heather M. Snyder, PhD, Alzheimer's Association vice president of medical and scientific relations. "With more than 190 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 bodies and brains. The Alzheimer's Association and its partners are leading, but more research is needed."

One study from the University of Texas Health Science Center at San Antonio Long School of Medicine focused on cognition and olfactory senses in a cohort of nearly 300 older adult Amerindians from Argentina who had COVID-19.

Looking at three and six months after COVID-19 infection, researchers determined that more than half showed persistent problems with forgetfulness, while about one in four also had cognition issues, including language and executive dysfunction. Severity of the original COVID-19 disease did not appear to affect those persistent symptoms, however.

"We're starting to see clear connections between COVID-19 and problems with cognition months after infection," explained lead author Gabriel de Erausquin, MD, PhD, MSc. "It's imperative we continue to study this population, and others around the world, for a longer period of time to further understand the long-term neurological impacts of COVID-19."

Another study from New York University’s Grossman School of Medicine determined that COVID-19 infection was linked to increases in Alzheimer’s biomarkers in the blood including total tau (t-tau), neurofilament light (NfL), glial fibrillary acid protein (GFAP), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), and species of amyloid beta (Aβ40, Aβ42) and phosphorylated tau (pTau-181). Researchers point out that those are indicators of injury in the brain, neuroinflammation and Alzheimer's disease.

The most common neurological symptom was found to be confusion due to toxic-metabolic encephalopathy (TME). "These findings suggest that patients who had COVID-19 may have an acceleration of Alzheimer's-related symptoms and pathology," Thomas Wisniewski, MD, of NYU. "However, more longitudinal research is needed to study how these biomarkers impact cognition in individuals who had COVID-19 in the long term."

A third presentation, from George Vavougios, MD, PhD, a postdoctoral researcher for the University of Thessaly (UTH) in Greece, looked at cognitive impairment and related health measures in 32 previously hospitalized mild to moderate COVID-19 patients. In assessments two months after discharge from the hospital, 56.2% presented with cognitive decline, according to the report, which notes that short-term memory impairments and multidomain impairment without short-term memory deficits were the predominant patterns of cognitive impairment.

"A brain deprived of oxygen is not healthy, and persistent deprivation may very well contribute to cognitive difficulties," Vavougios said. "These data suggest some common biological mechanisms between COVID-19's dyscognitive spectrum and post-COVID-19 fatigue that have been anecdotally reported over the last several months."

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