Fig. 3: Impact of SARS-CoV-2 infection and the COVID-19 pandemic on brain ageing, and the role of age and sex.

a Rate of change in brain age gap (BAG) is plotted against the average chronological age between two scans for the Pandemic–COVID-19, Pandemic–No COVID-19, and No Pandemic groups. Solid lines show best-fit associations; dot-dashed curves indicate 95% confidence intervals. b Violin plots display the distribution of the rate of change in brain age gap stratified by sex and pandemic status. For females: Pandemic group (G1), N = 255; No Pandemic group (G2), N = 297. For males: G1, N = 177; G2, N = 267. Cohen’s d-values, representing effect sizes, are reported for each comparison, alongside the FDR-corrected p-values from two-sample t tests between the groups. Interaction plots on the right highlight distinct patterns in grey matter (GM) and (white matter) WM between groups. Stars in the interaction plots indicate significant results, based on the FDR-corrected p-values of the interaction analysis determined by the two-factor, two-level permutation test. GM model results are displayed on the left and WM model results on the right in both panels.