MMP9 and Stroke: In linear mixed effects models adjusted for age, sex, vascular risk factors, stroke subtype, and baseline NIHSS, we detected trends wherein higher circulating levels of PDGF‐BB (β = 0.11, 95% confidence interval [CI]: –0.04, 0.26), MMP‐9 (β = 0.09, 95% CI: –0.06, 0.24), and Endo‐1 (β = 0.06, 95% CI: –0.09, 0.21) showed possible associations with increasing WMH volumes longitudinally; similar patterns were evident cross‐sectionally (Figure S3 and Table S5).