Fig. 4: The brain-PAD in different subgroups.

a The brain-PAD in controls and MDD patients. b Group analysis shows that the corrected brain-PAD is significantly higher in MDD patients than in controls (p < 0.0001, Cohen’s d = 0.31, 95% CI: 2.23–3.88). c The brain-PAD in antidepressant users and medication-free patients. d Group analysis shows that the brain-PAD is higher in MDD patients who are taking medication (+3.38 years, 95% CI: 1.86–4.90) than in those medication-free ones (+1.29 years, 95% CI: −0.14–2.72). The difference passes the statistically significant threshold (p = 0.0499).