White matter lesions (WML) are detected as hyperintensities on clinically frequently used T2-weighted FLAIR-images and can manifest as cognitive decline. Though most elderly subjects show WML, the pathogenesis is still unclear. Potential causes are small vessel damages and myelin-sheath deformations. We present data from 30 healthy elderly and 29 carotid stenosis patients measuring WML, individual watershed areas (iWSA), capillary transit-time heterogeneity (CTH) and DTI-based structural parameters. We hypothesize increased lesion load inside iWSAs and capillary dysfunction with structural damages in WML. Our results confirm those hypotheses and furthermore, indicate similar WML formation mechanisms in healthy aging and carotid artery stenosis.