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New study reveals insights on effects of COVID-19 in the brain

Research is the most comprehensive study on the virus in the brain to date

SUN CITY, Ariz. (Oct. 13, 2022) – A recent study conducted by Banner Sun Health Research Institute researchers has revealed new information and findings on how the COVID-19 virus invades the human brain. The study is the most comprehensive research on COVID-19 in the brain to date. Led by Drs. Geidy Serrano and Thomas Beach, the study looked at the brains of 42 people who died of COVID-19 and 107 control subjects, all from the institute’s Brain and Body Donation Program, who did not have the virus from 2019 to 2021.

“While this is a huge step towards understanding the effects of COVID-19 on the brain, it also points the way for extending such studies to ‘long COVID,’” Dr. Serrano said. “Over the next few years, we will be examining the brains of people who died at varying intervals after recovery from their initial infection. We should be able to answer important questions like whether the virus remains in the brain or even spreads further, and if there’s evidence of an autoimmune attack on the brain,” she said.

While the research resulted in one of the first major peer-reviewed studies on the effects of the COVID-19 virus on the brain so far, more work is needed to paint a fuller picture of what this means for a world slowly returning to normal. One potential effect that will require further research is the possibility that COVID-19 might increase risk for developing Alzheimer’s dementia or other neurodegenerative diseases. This is being considered as researchers continue to look into other global viruses and their effects, like the possibility that a surge of post-encephalitic parkinsonism in the early 1900s was linked to the 1918 H1N1 pandemic, and the potential of the Herpes virus or other common viruses being pathogenic factors for Alzheimer’s.

“In the past couple years, we have seen the devastation that the COVID-19 pandemic has caused for our communities through tragic, sudden loss,” said Dr. Thomas Beach, director of the Brain and Body Donation Program. “Through this new study, we are just beginning to get a glimpse of how the virus affects the brain, and we will continue to gain more insight on its potential long-term effects with further research.”

Key findings of the study include: 

COVID-19 brain invasion occurs in only a small percentage of fatal cases. In a survey of 16 brain regions of 20 COVID-19 autopsies, virus RNA was detected in a mere 2.5% of the 320 sampled brain regions. Additionally, the investigation found that only two out of the 42 total cases had major post-mortem brain destruction that was likely to have been related to their terminal COVID-19 illness.

The olfactory bulb, a neural structure involved in the sense of smell, is the most probable entry site of COVID-19 into the brain. Located near the front of the brain, it’s also the most likely brain region to harbor the virus. Nearly 40% of the 42 studied cases had it there. 

Researchers also found massive changes in the olfactory bulb and the closely-connected amygdala brain region. Aside from explaining the loss of the sense of smell in people with COVID-19, these changes could contribute to depression and other emotional changes in the weeks and months after infection.

The virus has slightly greater – but similar – effects on the brain compared with common end-of-life pneumonia. 

COVID-19 may cause immunosuppression of brain cells, resulting in a weakened immune system. Researchers discovered a significant decrease in microglia – cells that serve as the first line of defense for the central nervous system – in both the amygdala and cerebellum brain regions of COVID-19 subjects.

Since 1986, Banner Sun Health Research Institute, part of nonprofit Banner Health, has been a leader nationally and internationally in the effort to find answers to disorders of aging including Alzheimer’s and Parkinson’s disease. The Institute’s Cleo Roberts Center for Clinical Research and Civin Laboratory for Neuropathology work together to take new discoveries to clinical trials that foster hope for new treatments. Banner Health is Arizona’s leading health care provider and largest private employer. For more information, visit or visit us on Facebook.

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Banner Health COVID-19 Awareness Research

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