Evidence mounts on virus link to cognitive deficits

New studies show that COVID-19 has been linked to persistent cognitive deficits, including symptoms similar to those found in Alzheimer’s disease.

Several scientists from Europe, the United States and Latin America recently presented new research at this year’s Alzheimer’s Association International Conference, highlighting worrying associations between the novel coronavirus infection and neurological damage.

One study from the New York University Grossman School of Medicine discovered biological markers in the blood of COVID-19 patients similar to those found in people with brain injury, neuroinflammation and Alzheimer’s disease.

The study looked at 310 people admitted to NYU Langone Health medical center with COVID-19. Of those surveyed, 158 showed neurological symptoms and 152 had no such symptoms.

Researchers said that among those with symptoms, there was an increased presence of biological markers in the blood or spinal fluid, including defective tau proteins and neurofilament light chain, or NfL.

A component of brain cells, NfL can enter spinal fluid when nerves are damaged. Increased levels of defective tau proteins and NfL are indicators of some degenerative brain disorders, including Alzheimer’s.

“These findings suggest that patients who had COVID-19 may have an acceleration of Alzheimer’s related symptoms and pathology,” said Thomas Wisniewski, a professor of neurology at New York University who led the study.

Long-term issues

A separate study, submitted at the conference by researchers from the University of Gothenburg in Sweden, also found biomarkers of brain damage among COVID-19 patients admitted to the ICU.

The study found that biomarkers in some patients went back to normal levels in the months following the infection, though some patients experienced long-term cognitive issues.

Nelly Kanberg, a neuroscientist who co-authored the study, said the cause of brain damage remains uncertain, though inflammation and damage to blood vessels might be involved.

Heather Snyder, vice-president of medical and scientific relations at Alzheimer’s Association, said the combined new research points to “disturbing trends” that show that COVID-19 infections may lead to lasting cognitive impairment and “even Alzheimer’s symptoms”.