Adult iron supplementation does not exacerbate neurodegeneration markers in YAC128 HD mice. Mice were maintained on diets from 2–12 months of age. A. Brain weights of YAC128 HD and wild-type mice fed one of three custom iron diets. YAC128 mice have significantly decreased brain weights compared to wild-type litter-mates. Iron supplementation has no effect on brain weight in HD or wild-type mice. n = 12–15, B. Striatal volumes are decreased by HD but not by dietary iron level. There was a significant effect of genotype with YAC128 HD mice having lower striatal volumes across all iron groups, n = 4–6, C. Striatal cell body volumes are not altered by dietary iron intake level in YAC128 HD or wild-type mice. There was a significant effect of genotype with YAC128 HD mice having lower cell volumes across all iron groups. ME = main effect comparison. P-values: *p < 0.05, **p < 0.01, ***p < 0.001, n = 4–6.