COVID-19 linked to worsening brain health and markers of Alzheimer’s disease

29 July 2021

Research presented today (Thursday 29 July) at the 2021 Alzheimer’s Association International Conference (AAIC) in Colorado, suggests a link between COVID-19 and long-term memory and thinking problems. Researchers at the conference have also highlighted a link between cases of COVID-19 that include neurological symptoms with biological markers of Alzheimer’s disease.

Memory and thinking problems linked with loss of smell in people recovered from COVID-19

Researchers at the University of Texas looked at over 200 adults from Argentina with COVID-19 and compared this against 64 healthy individuals.

Volunteers completed memory assessments, as well as tests measuring their sense of smell.

They found that memory problems were associated with the loss of smell but not severity of COVID-19 infection.

COVID-19 linked with increased levels of Alzheimer’s disease markers in blood

Scientists in the US took blood from 310 people from Manhattan, Brooklyn and Long Island who had been admitted to hospital with COVID-19.

They looked at the levels of markers in the blood indicative of neurodegeneration. Neurofilament light chain (Nfl) is a structural component of nerve cells in the brain. It leaks from the brain when these nerve cells become damaged and can end up in the bloodstream and spinal fluid.

They found Nfl and a form of the tau protein linked with Alzheimer’s disease were strongly associated with the presence of neurological symptoms during COVID-19 infection.

Recovered COVID-19 patients who experience decline in memory more likely to have poor physical health

Researchers in Greece looked at memory and thinking problems in people two months after they’d been discharged from hospital after experiencing COVID-19. Of the 32 people in the study over half had cognitive problems and these were associated with poor physical health and low oxygen saturation.

What our expert said:

Speaking about the research, Dr Susan Kohlhaas, Director of Research at Alzheimer’s Research UK, said:
“It’s already clear that COVID-19 has had a disproportionate impact on people with dementia. 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

“Already at AAIC we have learnt that the number of people with dementia globally is set to almost triple by 2050, but this doesn’t consider potential new risk factors for the condition.

“These new findings underline that not only is COVID-19 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 it clear that more long-term follow-up and studies of people experiencing COVID-19 are required. These studies are predominantly from hospitalised patients, and we need to see a broader focus to encompass the widespread impact of COVID-19.

“In separate research, Alzheimer’s Research UK is liaising with other research funders to support work looking into long-term health impacts of COVID-19.

“If anyone is worried about their memory or thinking or persistent effects of COVID-19 they should consult with their doctor.”

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