Fig. 4: Influence of socio-demographic factors on brain ageing during the COVID-19 pandemic.

a The effects of socio-demographic factors, represented by indices of deprivation, on brain ageing in participants grouped by pandemic status. Each clock represents the difference in the mean rate of change in brain age gap (BAG) between individuals with low and high levels of specific socio-demographic factors. The clocks are presented separately for GM and WM models, with one set depicting participants in the No Pandemic group and another for participants in the Pandemic group. The socio-demographic factors studied include housing score, health score, employment score, income score, and education score. b–d Violin plots display the distribution of the rate of change in BAG for the Pandemic and No Pandemic groups, stratified by socio-demographic scores for (b) employment (No Pandemic: N = 111 low, N = 129 high; Pandemic: N = 105 low, N = 102 high), (c) health (No Pandemic: N = 110 low, N = 159 high; Pandemic: N = 111 low, N = 123 high), and (d) education (No Pandemic: N = 223 low, N = 126 high; Pandemic: N = 157 low, N = 95 high). High and low groups are colour-coded as purple and red, respectively. Each panel includes two plots for GM (left) and WM (right) results. Cohen’s d effect sizes and FDR-corrected p-values are reported for group comparisons based on two-sample t tests. Small plots on the right side of each panel depict interaction plots, suggesting the presence of interaction effects. These plots visualise how the mean rate of change in BAG deviates between the No Pandemic and Pandemic groups in both GM and WM models. Stars in the interaction plots indicate significant results based on the FDR-corrected p-values, calculated based on a two-factor, two-level permutation test, highlighting the interaction between the two factors.