WMH is one of the most obvious imaging traits in the aged brain. There is evidence that the WMH volume may have the potential to track with age and age-related cognitive decline. However, no study has investigated the trajectory of WMH progression and their impact on cognition during normal aging process. We show that increased age is nonlinearly correlated with increased PVWMH. In two-mediators mediation model, PVWMH is found to mediate the age-related decline of MMSE, but not DWMH. This study suggested that PVWMH could be a potential, and feasible biomarker in predicting age-related cognitive decline across the adult lifespan.