Alzheimer's Disease, COVID-19 Links

"While Alzheimer's is primarily characterized by harmful buildup of amyloid protein and tangles in the brain there is also extensive inflammation in the brain that highlights the importance of the immune system in Alzheimer's."

We have found that some of the same immune system changes can occur in both Alzheimer's disease and COVID-19."

"In patients with severe COVID-19 infection, there can also be inflammatory changes in the brain. Here we have identified a gene that can contribute to an exaggerated immune response to increase risks of both Alzheimer's and COVID-19."

“If we could develop a simple way of testing for these genetic variants when someone tests positive for COVID -19, then it might be possible to identify who is at greater risk of needing critical care but there is plenty more work to be done to get us there. Similarly, we hope that our research could feed into the development of a blood test to identify whether someone is at risk of developing Alzheimer’s before they show memory problems."

"We are also continuing to research what happens once this immune network has been activated in response to an infection like COVID -19, to see whether it leads to any lasting effects or vulnerabilities or if understanding the brain’s immune response to COVID -19 involving the OAS1gene, may help to explain some of the neurological effects of COVID -19."

Dervis Salih, lead author, study, UCL Queen Square Institute of Neurology, U.K. Dementia Research Institute, UCL

An elderly couple walks down a hall in Easton, Pa. (AP Photo/Matt Rourke)

Alzheimer's disease represents dementia's most common cause, a degenerative condition believed to result from the accumulation of certain proteins in the brain leading to the slow death of neurons. Eventually the process produces symptoms of memory loss, difficulty in thinking, or problems in solving exercises, along with changes in mood and behaviour. 

When COVID-19 began to strike worldwide, it was seen by researchers that the enduring brain fog associated with cases of Long COVID, along with other symptoms of the vial infection had similarities of note to the symptoms suffered by Alzheimer's patients. Researchers have now identified a genetic link between Alzheimer's and severe COVID-19 cases, with the potential of driving new insights into the treatment of both these diseases.

Published in the journal Brain, the study found that a variant of the OAS1 gene increases risk of developing Alzheimer's disease by three to six percent. Similar variants of the same gene are seen to increase odds of contracting severe COVID. There is hope among researchers that this overlap has the potential to inform scientists on other infectious diseases, and dementia.

Work produced previously by the researchers revealed a link between the degenerative disease and the OAS1 gene, expressed in microglia, a type of immune cell making up roughly ten percent of all brain cells. On further investigation it was found that a variation of this gene -- rs1131454 -- increased a baseline risk for the carrier of Alzheimer's disease. by 11 to 22 percent. The variant is carried by about half the population of Europe.

Four variants of OAS1 were investigated and the team found -- in addition to lessening the gene activity while increasing Alzheimer's risk -- the variants were linked -- or inherited together -- raising the risk of severe COVID by up to 20 percent.

 

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