The association between cerebral “dirty-appearing” white matter and progression of small vessel disease in community-dwelling older adults

Cerebral "dirty-appearing" white matter (DAWM) may represent early white matter alterations linked to cerebral small vessel disease (cSVD), though its role in cSVD progression is unclear. Therefore, DAWM prevalence and associations with cSVD progression were assessed on 1.5 T brain MRI of community-dwelling older adults from the AGES-Reykjavik cohort (<i>n</i> = 2506). On baseline MRI the presence of DAWM was visually rated. DAWM prevalence was relatively high in occipital (77%) and parietal (41%) white matter and relatively low in frontal (3%) and temporal (1%) white matter. In older adults with limited baseline white matter hyperintensity (WMH) burden (<i>n</i> = 1253, selected via median split), baseline DAWM ratings were associated with an increase in total WMH volumes (<i>p</i> = 0.004) and in the parietal (<i>p</i> = 0.004) and frontal (<i>p</i> < 0.001) white matter, as well as with new subcortical infarcts (<i>p</i> = 0.018) at 5-year follow-up. DAWM was not associated with new microbleeds (<i>p</i> = 0.823) or new enlarged perivascular spaces (<i>p</i> = 0.685) at follow-up. These findings show that DAWM is prevalent in community-dwelling older adults and is associated with progression of cSVD in individuals with limited WMH burden. DAWM may therefore be an early marker of cSVD progression and may help to identify older adults for personalized lifestyle interventions to prevent cognitive decline.