SLC6A3 and Cognitive impairment: Since increased dopamine levels are associated with a loss of dopamine transporters, dopamine receptors, and dopamine synthesis [50], [51], and such changes in the dopaminergic system over the whole brain are also involved in the aging process and cognitive deficit [52], [53], it is not surprising that a correlation between WMH volume and DSF performance was observed over all brain subregions in the Met homozygotes.