Cohen Medical Associates is a family medical center and research center located in Delray Beach, FL.
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More Studies Showing COVID-19’s Impact On the Brain

After three years of research on the novel coronavirus, more and more studies are confirming earlier evidence of COVID-19’s long-term effect on the body, particularly the brain.

Our primary care doctors in Delray Beach are especially concerned about the impact on seniors, who are already at risk for cognitive decline. And the findings are striking.

Alzheimer’s Trigger?

One study, for example, published last September in the Journal of Alzheimer’s Disease, looked at the electronic health records of more than six million Americans over the age of 65 who had COVID-19. The researchers, from Case Western Reserve University School of Medicine, found that those who had been infected had a greater risk of being diagnosed with Alzheimer’s disease within the following year.

“We know that COVID can affect the brain, but I don’t think anyone had looked at new diagnoses of Alzheimer’s,” Pamela Davis, one of the study’s co-authors and a research professor at Case Western, told The Washington Post.

Her colleague Rong Xu said she’d expected to see some increase in the disease among seniors who had COVID but was surprised “by the extent of the increase and how rapidly it occurred.”

Another doctor, Gabriel de Erausquin, director of the Laboratory of Brain Development, Modulation, and Repair at the University of Texas Health San Antonio, cautioned that the study was “limited,” and less accurate than imaging or spinal fluid tests to measure the proteins typically present in those with Alzheimer’s.

Brain scans that look for such structural changes as shrinking of certain regions are a more accurate indicator, he told The Post.

Other Studies

One large study, however, published last March in the journal Nature, did just that. Researchers in the UK reviewed a database involving 45,000 people, finally narrowing the search down to 785 people who had had COVID-19.

All 785 participants had undergone brain scans both before and after contracting COVID-19. The British team from Oxford found that the subjects’ brains showed more significant tissue loss in specific regions of the brain relating to smell, as well as a larger reduction in overall brain size.

Specifically, they found differences in the gray matter, i.e., the neurons that process information. Those who had contracted COVID-19 showed a reduced thickness in the frontal and temporal lobes. The researchers also performed cognitive tests on the subjects and found they performed worse in processing information.

In this study, researchers found that even a mild case of COVID-19 resulted in subtle brain tissue damage, including loss of brain volume.

Another researcher, Maria Mavrikaki of Beth Israel Deaconess Medical Center in Boston, tried a different approach. She and her team studied the brains of those who had died from COVID-19, comparing them to those who died from other causes.

The COVID-infected brains showed increased activity in genes associated with immune responses and decreased activity in genes related to cognition, learning, and memory, she told Bloomberg science columnist Faye Flam.

In addition, the changes resembled those other researchers had found for what she called “low cognitive performance” before they died, Mavrikaki said.

Additional Evidence

Finally, an August 2022 study by researchers at the University of Oxford examined health records data from more than a million people around the world, including the U.S., Australia, Britain, Spain, India, and Taiwan, for people diagnosed with COVID-19 between January 20, 2020, and April 13, 2022.

They found those infected were at greater risk of developing dementia, epilepsy, insomnia, stroke, and brain fog up to two years after infection.

Other results:

  • 4.5 percent of those over 65 developed dementia in the two years after infection, compared to 3.3 percent of the control group.
  • There were also 85 cases of psychotic disorders among patients over 65 for every 10,000 people following a COVID-19 infection.
  • Among those between the ages of 18 and 64, 6.4 percent reported brain fog after two years, compared to 5.5 percent of the control group.

“The findings shed new light on the longer-term mental and brain health consequences for people following COVID-19 infection,” Max Taquet, who led the analysis, said in a University of Oxford news release.

Aim for Prevention

Along with the possibility of other lasting effects—known as long COVID—these latest studies are one more reason our Delray Beach primary care doctors will continue to urge our patients to take precautions against becoming infected.

Although the latest figures for Florida show the rates of hospitalization and deaths have been declining in recent weeks, we still recommend that our patients get the updated booster against the disease.

Known as a “bivalent” vaccine because it protects against the BA.4 and BA.5 variants as well as the original strain of the virus, the CDC recently released figures showing it also provided protection against the latest subvariant, XBB.1.5, which is the predominant strain circulating at the moment.

In adults up to age 49, the latest boosters from Pfizer-BioNTech and Moderna were 48 percent effective against symptomatic infection from the XBB.1.5 subvariant, the CDC reported. Among adults older than 65, they were 43 percent effective.

And because the virus spreads so easily, often from people who have no symptoms, we also urge our patients to continue wearing high-quality masks (N95s are best) in indoor spaces with poor air circulation.

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