Covid-19 virus linked to brain disorders

The Covid-19 virus may trigger an inflammatory response in the brain similar to that which ­occurs in Parkinson’s disease and Alzheimer’s.

The Covid-19 virus. Picture: AFP

The Covid-19 virus may trigger an inflammatory response in the brain similar to that which ­occurs in Parkinson’s disease and Alzheimer’s, exacerbating the risk of developing neuro­degenerative conditions for ­susceptible individuals.

Researchers at the University of Queensland found that Covid-19’s activation of an inflammatory pathway in the brain began a chronic and sustained process of killing off neurons.

The discovery was made when scientists from UQ’s School of Biomedical Sciences, together with virologists from the School of Chemistry and Molecular Biosciences, grew a type of immune cell called microglia from donor blood and infected the cells with the virus that causes Covid-19.

These are the key cells ­involved in the progression of brain diseases like Parkinson’s and Alzheimer’s.

“These cells, normally, in the brain they respond to pathogens and cell injury, and they can induce an inflammatory response that protects us from disease and infection,” UQ pharmacology professor Trent Woodruff said.

“But in many diseases like Parkinson’s and Alzheimer’s, it’s known that these same cells don’t really get switched off, and the microglia become what we call ‘angry’, and this can drive further loss of brain cells that ­occurs in these diseases.

“It’s thought that there’s this persistent activation of these cells over a long period of time, many years if not decades prior to actually having symptoms of these diseases. These cells become activated and start releasing many of these toxic factors that have very direct effects on killing neurons.”

The UQ research was co-led by Alberto Amarilla Ortiz and Daniel Watterson, and involved 33 co-authors across UQ and ­internationally. It was published in Nature’s Molecular Psychiatry.

A potential link between ­Parkinson’s disease and Covid-19 has been hypothesised since early in the pandemic.

A scientific paper published in the prestigious journal Nature in 2020 found Covid-19 was genetically correlated to other neurodegenerative diseases but did not identify a causal association. Other papers have shown Covid-19 appears to worsen symptoms in those with pre-existing neurodegenerative disease.

Not all people who contract Covid-19 experience an inflammatory process in the brain. Professor Woodruff said it was most likely that Covid-19 may trigger or hasten the development of Parkinson’s or Alzheimer’s in those already susceptible to those diseases, but not necessarily in other individuals.

“If someone is already predisposed to Parkinson’s, having the Covid-19 virus could be like pouring more fuel on that ‘fire’ in the brain,” Professor Woodruff said. “The same would apply for a predisposition for Alzheimer’s and other dementias that have been linked to inflammasomes.”

But the scientists said treatments to combat this inflammatory process were likely to be available in the next decade.

UQ is developing an inhibitory drug, currently in clinical trials with Parkinson’s patients, which it is hoped may also block the inflammatory pathway activated by the Covid-19 virus.