A new study has found that living through the COVID-19 pandemic aged people's brains, regardless of whether people were infected.
The research adds to growing data about the pandemic's long-term impact on global health and brain development.
The study showed that the pandemic accelerated brain aging by 5.5 months on average. Changes were most noticeable in older people, men, and in those from more disadvantaged socioeconomic backgrounds.
Brain age relates to cognitive function and can differ from a person's actual age.
Someone's brain age can be delayed or advanced by diseases like diabetes, HIV, and Alzheimer's disease. Premature brain aging can affect memory, sensory function, and emotional function. The authors say the brain aging they observed may be reversible.
"The pandemic put a strain on people's lives, especially those already facing disadvantages. We can't yet test whether the changes we saw will reverse, but it's certainly possible, and that's an encouraging thought," said the study's senior author Dorothee Auer, a neuroscientist at University of Nottingham, UK.
Frank Slack, Director of HMS Initiative for RNA Medicine and the Cancer Research Institute at Harvard Medical School, US, said the "work is a tour de force showing in a large population that COVID had severe effects on brain health, especially in males and the elderly." Slack was not involved in the study.
The study was published in Nature Communications.
Did the pandemic affect people's brain function?
The study aimed to investigate the adverse effects of COVID-19 on physical and cognitive brain aging using brain imaging and cognitive testing.
The researchers analyzed brain scans from healthy adults taken before and after the pandemic as part of the UK Biobank study.
"[This] gave us a rare window to observe how major life events can affect the brain," said Stamatios Sotiropoulos, a neuroscientist at University of Nottingham and the study's co-lead author.
First, the researchers used brain scan data from 15,334 healthy people to train a machine learning algorithm that could accurately estimate their brain age.
They then used the model to predict the brain age of 996 healthy adults before and after the COVID pandemic.
One group of participants had scans before and after the pandemic began, while a comparison group only had their scans taken before the outbreak.
The pandemic aged people's brains, even those without COVID infection
The study revealed that the brains of participants from the pandemic group had aged an average 5.5 months faster than the control group, even when matched for a range of health markers.
Jacobus Jansen, a neuroscientist at Maastricht UMC, Netherlands, said the surprising result was that "aging is independent of actual COVID-19 infection."
However, only participants who were infected by COVID-19 showed a drop in cognitive abilities like mental flexibility and processing speed. This may suggest that the pandemic's brain aging effect without infection may not cause noticeable cognitive symptoms.
The next question researchers are aiming to answer is how the pandemic had long-term effects on people's cognitive health. Other studies have suggested certain genetic factors could make some people more predisposed to COVID-related brain aging.
"[In 2022], we described premature aging in the brains of severe COVID. Unfortunately, all of the patients we examined had passed away from COVID, precluding detailed follow-up and analysis of brain architecture over time," Slack said.
"It will be interesting to start to ask whether the aging effects seen in this study are related to the gene expression changes we saw in our study," Slack said.
Can you reverse brain aging?
Neuroscience studies suggest there are ways to slow down brain aging and reduce the risks of cognitive decline.
Exercise, for example, is a known protective factor in brain aging, which is why "it would be valuable to assess the contribution of changes in exercise patterns during the pandemic, alongside psychological stress, within their model," said Maria Mavrikaki, a neuroscientist at Harvard Medical School, US, who was not involved in the study.
Other studies suggest that brain aging can be slowed down by lifestyle changes like eating a healthy diet, staying physically and mentally active, managing stress, and getting adequate sleep promotes healthy brain aging.
These small changes can add up, so making them part of your routine can support your brain function in the future.
