And coronavirus patients are more susceptible to long-term memory and thinking problems, a separate study has found.
In the first case, scientists found higher levels of markers of Alzheimer’s disease, which causes dementia, in the blood of people who had suffered neurological complications after being infected with the virus.
“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, Alzheimer’s Association vice-president for 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.”
As part of the research, scientists in the US took blood from 310 people in New York admitted to hospital with Covid-19.
Markers in the blood linked with Alzheimer’s were strongly associated with the presence of neurological symptoms during Covid-19 infection.
Thomas Wisniewski, a professor of neurology, pathology and psychiatry at New York University School of Medicine, who led the research, said: “These findings suggest that patients who had Covid-19 may have an acceleration of Alzheimer’s-related symptoms and pathology.”
But he said more studies were needed to establish how the biomarkers affect cognition in the long term in people who have had Covid-19.
It’s not known whether people suffering from Covid’s neurological symptoms who show signs of Alzheimer’s are already predisposed to the condition.
However, Alzheimer’s diagnoses also appear to be more common in patients in their 60s and 70s who have had severe Covid, said Gabriel de Erausquin, a professor of neurology at UT Health San Antonio.
“It’s downright scary,” he told NPR.
Doctors have previously found that scans taken before and after a person develops Covid suggest it can cause changes that overlap with those seen in Alzheimer’s, and genetic studies show some of the genes that increase a person’s risk of getting severe Covid-19 also raise the risk of developing Alzheimer’s, NPR reported.
The new findings, which have yet to be published, were presented at the 2021 Alzheimer’s Association international conference in Colorado, US.
Separate research has found a link between Covid-19 and long-term memory and thinking problems.
Researchers at the University of Texas looked at more than 200 adults from Argentina with Covid-19 and compared them with 64 healthy individuals.
They found that memory problems were linked to loss of smell, but not to the severity of Covid-19 infection.
When participants were studied up to six months after Covid infection, more than half showed persistent problems with forgetfulness, and roughly one in four had additional problems with cognition, including with language.
Another study from Greece, also presented at the conference, found that recovered Covid-19 patients who experienced a decline in memory were more likely to have poor physical health.
Susan Kohlhaas, director of research at Alzheimer’s Research UK, said: “Relatively little is known about the long-term effects of Covid-19, including subsequent risk of memory and thinking problems, or the long-term risk of diseases like Alzheimer’s.
“These new findings underline not only that Covid-19 is a serious illness, but that we need to monitor potential long-term effects.
“The evidence for persistent problems with memory and thinking after a Covid-19 infection isn’t yet clear, and like all findings presented at conferences, we must wait to see them published in full and scrutinised by other experts to draw firmer conclusions.
“These results make clear that more long-term follow-up and studies of people experiencing Covid-19 are required.”
A year ago, a professor at the University of Michigan warned that inflammation caused by Covid can have long-lasting effects on memory, increasing the risk of memory loss and cognitive decline.
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