August 12, 2021

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COVID-19, Alzheimer’s Disease, and Memory Loss: What We Know

COVID-19 May Accelerate Alzheimer's and Other Cognitive Issues
  • Researchers are learning more about how COVID-19 may impact memory.
  • In one study1 in 10 patients have been reporting memory problems after mild cases of COVID-19 that did not require hospitalization, even 8 months after disease.
  • People who have recovered from COVID-19 but presented with cognitive decline are more likely to be in poorer physical health and have low O2 saturation in their blood.
  • COVID-19 may heighten the risk of developing Alzheimer’s, and COVID-19 can cause an increase in blood-based molecular biomarkers for Alzheimer’s disease.

COVID-19’s immediate physical effects have been vastly studied, but much remains a mystery regarding long-term complications.

In particular, scientists are scrambling to understand the disease’s long-term effects on neuropsychological health.

Neurological signs of COVID-19, both short and long term, may include symptoms such as the loss of smell and taste and cognitive and attention deficits, known as “brain fog.”

And now, new research shows how COVID-19 continues to affect the brain long after recovery and how some symptoms may be precursors to more serious health problems in the future.

Here is a roundup of the latest studies and newest research presented at the Alzheimer’s Association International Conference (AAIC) on COVID-19 and its neurocognitive effects.

Memory problems 8 months after disease

As part of a Norwegian study published in the JAMA Network OpenTrusted Source, scientists reached out to more than 53,000 participants between Feb. 1 and April 15, 2020. These adults included those who tested positive for SARS-CoV-2, those who tested negative, and a sizeable number of untested individuals to represent the general population.

Over 13,000 participants responded to the questionnaire sent out by Arne Søraas, PhD, from Oslo University Hospital in Norway, and his colleagues and around 9,000 followed up.

The mean age of participants was 47, and 66 percent of the participants were women.

Søraas and his team found that more than 1 in 10 patients reported memory loss 8 months after testing positive.

At least 41 percent of those who reported having memory problems months after infection said their overall health had also worsened over the past year.

Of those who tested positive 8 months after infection, approximately 11 percent reported memory loss, and 12 percent had problems concentrating.

Those who tested positive were twice as likely to report cognitive problems.

They also reported more memory problems than those who tested negative or the untested population.

In addition, more than 50 percent of patients experienced persistent fatigue, with 20 percent saying this limited their work and general life activities.

The symptoms reported relatively equally by the three groups were feeling depressed, having less energy, or having pain.

“Self-reported memory problems are also a risk factor for later mild cognitive impairment or dementia,” they said.

Although the self-reported nature of memory problems may not present a 100 percent accurate picture, past studies have listed them as a risk factor for developing dementia or mild cognitive impairment later in life.

The findings, according to the authors, suggest that SARS-CoV-2 may negatively impact memory even 8 months after having a mild case of the disease, and this can be associated with a worsening of health and Post-Acute Sequelae of SARS-CoV-2 infection (PASC), the medical term coined for long COVID in expert circles.

Finding a link between long COVID-19 and an impact on cognition

Meanwhile, new research reported at the virtual Alzheimer’s Association International Conference (AAIC) 2021 in Denver found links between COVID-19 and persistent cognitive deficits.

One of the most significant initial findings presented at AAIC 2021 was from a Greece and Argentina consortium, which suggested that:

  • Older adults frequently experience lasting cognitive impairment, including persistent lack of smell, after recovering from COVID-19.

The other key findings were:

  • COVID-19 patients presenting with neurological symptoms are likely to have biological markers in their blood that indicate brain injury, neuroinflammation, and Alzheimer’s.
  • Individuals who experience cognitive decline after COVID-19 are more likely to have low blood oxygen levels after short periods of physical exertion as well as be in an overall poorer physical condition.

“These new data point to disturbing trends showing COVID-19 infections leading to lasting cognitive impairment and even Alzheimer’s symptoms,” Heather M. Snyder, PhD, Alzheimer’s Association vice president of medical and scientific relations, said in a statement.

“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.”
– Heather M. Snyder, PhD, Alzheimer’s Association VP of medical and scientific relations

Link between cognitive impairment and loss of smell

Another study analyzed 300 older adult Amerindians from Argentina who had COVID-19, 3 and 6 months after initial infection.

Over half of the patients showed persistent problems with forgetfulness. At the same time, 1 in 4 had additional problems with cognition, including issues with language and executive dysfunction, such as difficulty organizing, misplacing items, and not being able to deal with frustration.

These setbacks, the research found, were associated with persistent problems in the smell function but not with the severity of the original COVID-19 disease.

“We’re starting to see clear connections between COVID-19 and problems with cognition months after infection,” said Dr. Gabriel de Erausquin of the University of Texas Health Science Center at San Antonio Long School of Medicine.

“It’s imperative we continue to study this population, and others around the world, for …