Scientists Investigate Covid-19 and Risk of Dementia

At the newly opened Covid-19 neurology clinic at Loyola Medicine, doctors treat people suffering from chronic fatigue, headaches, impaired sense of smell and or taste, memory loss, troubles with other mental skills, and brain fog.

Some people report having trouble concentrating; others can’t sleep. The symptoms are just a few of the common neurological and cognitive issues that people with Covid-19 sometimes face.

The clinic is a one-stop shop for people seeking help, says Jose Biller, MD, chair of Loyola University Medical Center’s neurology department. It’s one of many that are opening around the country, including a post-Covid care unit at Rush University Medical Center that help people suffering from the cognitive effects of long-haul Covid.

Scientific leaders have formed an international consortium to study how SARS-CoV-2 — the virus that causes Covid-19 — might impact cognitive changes in the brain that may contribute to dementia.

“A large percentage of the hospitalized patients with Covid-19 have neurological symptoms,” Biller says. “A wide range of central nervous system and peripheral nervous system manifestations have been reported among those seriously ill patients, particularly those who were hospitalized in intensive care unit settings.” Those people may experience delirium, which can affect brain health.

While many people recover within a couple of weeks, up to 10% of people who’ve had Covid-19 continue to feel its effects for much longer, according to recent research published in The BMJ.

Scientists don’t yet know what percentage of people who contract Covid-19 might have neurological and cognitive problems or could develop dementia, especially over the long-term. The virus is, after all, only a year old, but we may soon know a lot more than we do now.

Investigating Covid-19’s long-term effects

To get a better understanding of what could happen to people who have experienced Covid-19’s cognitive effects over time, an international team of collaborators is planning to study Covid-19 data from more than 30 countries, an effort detailed in a paper published in January in the journal Alzheimer’s & Dementia.

The Study of SARS-CoV-2’s Impact on Behavior and Cognition, which received initial funding from the Alzheimer’s Association and technical guidance from the World Health Organization, will evaluate people of different ages and genetic backgrounds six, nine, and 18 months after infection.

Tracking and measuring cognitive challenges associated with Covid-19 could help researchers comprehend the virus’s long-term effects and mechanisms, says Heather M. Snyder, PhD, a co-author of the study and vice president of medical and scientific relations at the Alzheimer’s Association. “It’s very important that we get ahead of this issue, compile and track the available global data, and get a better grip on what the long-term impact may be,” she says.

What happens to the Covid-19 brain?

When someone is infected with SARS-CoV-2, the body fights off the virus, a process that can cause inflammation. Also, the virus itself may cross the blood brain barrier — a net of cells that surrounds the brain and typically prevents the blood from transporting pathogens there — and cause inflammation in the central nervous system.

Being a respiratory virus, SARS-CoV-2 can travel through the nose to the brain, where it attacks the olfactory bulb and other regions of the brain, a reason why people may lose their sense of smell, neurologists say. The infection may also lead to brain cell death, or neurodegeneration.

Research into the long-term cognitive and neurological effects from the 1918 flu pandemic, as well as the MERS and SARS viruses, shows that infection can result in issues related to cognitive function, including movement, thinking, and emotion.

“We have known for decades that people with severe viral infections can have very long-term, cognitive, emotional, and physical changes that can really impact their functioning well beyond their time in the hospital,” says Abigail Hardin, PhD, a psychologist at Rush Medical College. “Now that we have Covid, we’ve got 25 million Americans who are all experiencing this at once, so it’s just so very clear to us now that this is happening to a large number of people.”

Some changes in the brain that result from SARS-CoV-2 infection may lead to an increased risk for dementia, says Chad Yucus, MD, a neurologist at NorthShore University HealthSystem who specializes in memory disorders and dementia. The inflammation seen in Covid-19 patients is also seen in degenerative diseases that cause dementia, he says, so it’s possible that the two illnesses may involve the same inflammatory pathology, a link the researchers could uncover.

The value of international collaboration

The new research could offer insight into which treatments or vaccines may help slow or prevent cognitive changes, Snyder says. The patients in the studies often have been discharged from the hospital, and some may have been given medication or other treatments. The study’s scientists will analyze and report the downstream effects. “We may find that there are certain types of treatments that have better outcomes, not only for the Covid-related symptoms, but also for the brain, memory, and thinking skills, or other neurological outcomes of the individuals,” she says.

Though no researchers in the Chicago area are currently involved in the international research, a number are conducting their own inquiries and note the importance of the investigation. “This study is showing a great thought process in exploring what memory changes may persist,” Yucus says.

In the meantime, doctors advise that anyone experiencing mental fog or cognitive issues related to Covid-19 see a neurologist or, better yet, a Covid-19 clinic like the ones at Loyola or Rush. Specialists can track changes in memory over time, including the possible onset of dementia.

“What can be done for long-haul Covid patients to alleviate their ordeal?” asks Loyola’s Biller. “Streamlined, multidisciplinary, coordinated care seems essential.”

Results from the study could further guide treatments — and shed light on the virus’s impact on the risk of later-life cognitive decline and dementia. The first outcomes are expected in late 2022.