Researchers from an international consortium seeking to understand the long-term consequences of Covid-19 on the central nervous system, find memory problems and biological markers similar to those seen in patients with Alzheimer’s disease. Both diseases were marked by inflammation of the brain.
Dr Gabriel de Erausquin, professor of neurology at the University of Texas Health Sciences Center, and his colleagues studied more than 200 Argentine adults aged 60 and over infected with Covid-19.
Those who had persistent loss of smell were more likely to experience cognitive problems, they told the Alzheimer’s Association international conference.
Three to six months after becoming infected, more than half of patients were still struggling with forgetfulness, and about a quarter experienced additional cognitive problems. A patient’s degree of illness with Covid-19 was not an indicator of his cognitive decline.
Cognitive problems – including persistent forgetfulness, difficulty sequencing tasks, and forgetting words and phrases – are similar to those seen in patients with Alzheimer’s disease. Erausquin noted that the parts of the brain responsible for smell overlap with those affected by Alzheimer’s disease.
He noted that the cognitive symptoms seen by his team appear to be distinct from ‘brain fog’ associated with long-term symptoms of Covid-19, sometimes seen in younger patients.
“Brain fog in younger individuals has a different flavor, if you will,” Erausquin said. “They have more problems with attention, more problems concentrating and often have more anxiety and depression. “
It’s too early to say whether cognitive problems will worsen over time – as they would in patients with Alzheimer’s disease – or whether those patients will recover, Erausquin said.
Biological markers linked to Alzheimer’s disease
In additional research presented at the conference, Dr. Thomas Wisniewski, professor of neurology at the Grossman School of Medicine at New York University, and his colleagues found that Covid-19 patients over the age of 60 had Biological blood markers also found in Alzheimer’s patients.
Among 310 Covid-19 patients admitted to New York University Langone Health, the team found that those with neurological symptoms had higher levels of biomarkers linked to Alzheimer’s disease. These biomarkers include a protein called tau which has been linked to Alzheimer’s disease and other compounds known as neurofilament lumen – an indicator of nerve cell damage – and others.
“These results suggest that patients with COVID-19 may have an acceleration of symptoms and pathology related to Alzheimer’s disease,” Wisniewski said in a statement.
Wisniewski said more research is needed to understand how these biomarkers affect long-term cognition in people infected with Covid-19.
“It’s the kind of thing that makes you suspect that there may actually be an overlap with Alzheimer’s disease, in a way,” Erausquin said. “But it’s very early in the game. We need a lot more data. “
Researchers have long been listening to potential links between respiratory disease and the brain, Heather Snyder, vice president of medical and scientific relations at the Alzheimer’s Association, told CNN. She noted that similar changes in cognition and behavior, such as increased anxiety and sleep disturbances, were seen in people infected during outbreaks of Severe Acute Respiratory Syndrome or SARS in 2003-2004 and of Middle East Respiratory Syndrome or MERS.
Snyder said researchers are working hard to understand the long-term consequences of these findings on Covid-19 and cognition.
“We also have to really try to understand the impact on the brain, as a whole, because we know that when our brains can be vulnerable for other reasons, it can also increase our risk for Alzheimer’s,” Snyder said. .
Erausquin pointed out that research does not show that Covid-19 increases a person’s risk for Alzheimer’s disease, and there are some big questions that can only be answered over time.
“I’m trying to understand if the virus accelerates a pre-existing disease, or if it causes the start and progression of a new process similar to Alzheimer’s disease, or if it behaves like a solved problem that will recover. completely, ”he said. ” We do not know yet. “
What researchers do know is that older people can take steps to reduce their overall risk of cognitive impairment, such as being physically active, staying in social contact, and maintaining a healthy diet.
“I think it’s important to remember that whatever the reason for cognitive decline, the brain is plastic, and a lot of these interventions are likely to reduce the risk of impairment or the risk of progression,” Erausquin said. .