Brains Under Stress: Unravelling the Effects of the COVID-19 Pandemic on Brain Ageing

The impact of SARS-CoV-2 and the COVID-19 pandemic on cognitive and mental health is recognised, yet specific effects on brain health remain understudied. We investigated the pandemics impact on brain ageing using longitudinal neuroimaging data from the UK Biobank. Brain age prediction models were trained from hundreds of multi-modal imaging features using a cohort of 15,334 healthy participants. These models were then applied to an independent cohort of 1,336 participants with two MRI scans: either both collected before the pandemic ("Control" groups), or one before and one after the pandemic onset ("Pandemic" group). Our findings reveal that, even with initially matched brain age gaps (predicted brain age vs. chronological age), the pandemic significantly accelerated brain ageing. The "Pandemic" group showed on average 11-month higher deviation of brain age gap at the second time point compared with controls. Accelerated brain ageing was more pronounced in males and those from deprived socio-demographic backgrounds, with average increases of 3.3 and 7 months, respectively. These deviations existed regardless of SARS-CoV-2 infection. However, accelerated brain ageing correlated with reduced cognitive performance only in COVID-infected participants. Our study highlights the pandemics significant impact on brain health, beyond direct infection effects, emphasising the need to consider broader social and health inequalities.