Study shows Covid-19 in fathers may affect offspring's brain, cause anxiety

Changes in sperm caused by Covid-19 in a mouse could affect the offspring's brain development and cause anxious behaviours, a study has found, suggesting that the viral disease may have long-lasting effects on future generations, even as the results would need to be verified in humans, researchers said.

The team from Australia's Florey Institute of Neuroscience and Mental Health found that an offspring mouse conceived after a father has been infected with the SARS-CoV-2 virus and developed Covid-19 symptoms have higher levels of anxiety-like behaviours.

"We let male mice recover from SARS-CoV-2 infection for a few weeks before they mated with healthy females. We found that the resulting offspring showed more anxious behaviours compared to offspring from uninfected fathers," Elizabeth Kleeman, research officer and first author of the study published in the journal Nature Communications, said.

All offsprings from Covid-19-affected fathers were seen to display increased anxiety-like behaviours.

"Using an established mouse-adapted SARS-CoV-2 preclinical model, we infected adult male mice with the virus, or performed a mock control infection, and bred them with naive female mice four weeks later, when males were no longer infectious. Here we show that offspring of infected sires display increased anxiety-like behaviours," the authors wrote.

Lead researcher Anthony Hannan said it is known that male mice exposed to adverse environmental and lifestyle factors, such as consuming a poor diet before mating, can change brain development and behaviour in offsprings.

"This is because the father's experiences can alter the information carried in sperm, including specific RNA molecules, which transmit instructions for offspring development," Hannan said.

Analysis of RNA gene material from infected fathers' sperm showed altered molecules, including those involved in regulating genes known to be important for brain development.

Female offspring mice also had significant changes in how specific genes in the brain's hippocampus region -- important for regulating emotional responses such as anxiety and stress -- behaved, the study found.

"These kinds of changes in the hippocampus, as well as other brain regions, may contribute to the increased anxiety we observed in offspring, via epigenetic inheritance and altered brain development," co-senior author Carolina Gubert said.

Epigenetics refers to the process by which a gene interacts with the environment to produce an observable behaviour.

Hannan said the study is the first of its kind, and added that if the results are verified in humans, millions of children and families worldwide could be impacted, "with major implications for public health".

"While more research is needed, particularly in the sperm and offspring of humans infected with the SARS-CoV-2 virus, these findings suggest that the Covid-19 pandemic could have long-lasting effects on future generations," the lead researcher said.

"Our discoveries highlight the importance of understanding the impacts of this virus and infectious disease, not only on those directly infected, but also on their children who may be affected by their parent's experience with Covid-19," Hannan added.