Even without infection, the COVID-19 pandemic aged our brains. A new study found that accompanying stressors like isolation and uncertainty accelerated brain aging, especially in men, older adults, and those from disadvantaged backgrounds.
The COVID-19 pandemic had a profound effect on people around the world, with subsequent studies showing a particular impact on mental health and well-being linked with infection with the virus and with the social restrictions imposed during the pandemic.
Now, new research led by the University of Nottingham in the UK suggests that the COVID-19 pandemic accelerated brain aging, even in people who managed to avoid infection with the virus.
“What surprised me most was that even people who hadn’t had COVID showed significant increases in brain aging rates,” said the study’s lead author, Ali-Reza Mohammadi-Nejad, PhD, a research fellow in the University of Nottingham’s Sir Peter Mansfield Imaging Center (SPMIC). “It really shows how much the experience of the pandemic itself, everything from isolation to uncertainty, may have affected our brain health.”
The researchers examined brain MRI scans from nearly 1,000 healthy individuals aged 47 to 80, taken from the UK Biobank database. Two groups were studied: the Pandemic Group (432 people), who’d had one scan before and one after the pandemic began, and were subdivided into those with and without recorded COVID-19 infection; and the Control Group (564 people), who’d had two scans prior to the pandemic.
They developed models using scans from over 15,000 healthy individuals, including separate models for gray matter and white matter, and for men and women. Gray matter contains short projections called dendrites that help neurons receive signals. White matter transmits those signals between gray matter areas and to more distant parts of the brain and spinal cord. To ensure unbiased predictions, the model the researchers developed used hundreds of brain imaging features and statistical corrections.
The main metric they measured was the rate of change in brain age gap (RBAG) between the two scans, adjusted for the time between scans. They found that the Pandemic Group showed significantly higher brain aging than the Control Group. The effect, which was moderate to large, was present regardless of whether the individual was infected with SARS-CoV-2. However, only the COVID-infected group showed associated declines in cognitive performance, particularly in the Trail Making Test, a measure of mental flexibility, processing speed, and executive functioning. This suggests that, while the pandemic accelerated everyone’s brain aging, only the infection led to measurable thinking difficulties.
Older individuals had more rapid brain aging, especially those who’d been infected with the virus. Men were affected more than women, particularly in the gray matter. People from deprived socioeconomic backgrounds, such as those with poor employment, health, education, and income scores, showed greater increases in brain age gap. These disparities suggested that social and health inequalities amplified brain vulnerability during crises.
Because the study is observational, it can show an association between the COVID-19 pandemic and brain aging, but it can’t establish a direct cause-and-effect relationship. There are other limitations to the study. MRI scans were taken only at two time points, so the researchers couldn’t assess whether brain aging was reversible over time. Also, study participants were healthy individuals aged 45 and older, which means the findings may not apply to younger people or those with preexisting illnesses. And there is a potential for bias given that most COVID-19 infections were mild, and participation in the UK Biobank is voluntary, which may exclude more vulnerable individuals.
Regardless of its limitations, the study has practical implications. It shows that psychological stressors such as social isolation, health anxiety, and financial insecurity can physically age the brain, even without infection. It also emphasizes the importance of addressing social determinants of health to promote greater equity in public health matters.
“This study reminds us that brain health is shaped not only by illness, but by our everyday environment,” said Dorothee Auer, Professor of Neuroimaging at the University of Nottingham and the study’s corresponding author. “The pandemic put a strain on people’s lives, especially those already facing disadvantage. We can’t yet test whether the changes we saw will reverse, but it’s certainly possible, and that’s an encouraging thought.”
The study was published in the journal Nature Communications.
Source: University of Nottingham
