The study of the impact of polyQ expansion driven proteotoxicity on cell metabolism has evi-denced NAD molecule as a central player in regulating metabolic response and cell repair in neurodegeneration. The decline in NAD intracellular levels represents a hallmark of ageing aris-ing from a dysregulation between NAD-consuming and biosynthetic enzymatic reactions in which NMNAT plays a key role. By an integrated bioanalytical and proteomic experimental design, the derangement of NAD metabolism deriving from the accumulation of polyQ-Htt protein has been analysed in Saccha-romices cerevisiae harbouring a 103Q-Htt and compared with wild-type Htt, in absence and in presence of a phenolic extract from EVOO, as a source of antioxidant bioactive compounds. Quantification of NAD and its precursors and proteomic analysis of the differential protein ex-pression has been performed by LC-DAD-MS. Chronological lifespan and NAD homeostasis was strongly impaired by proteotoxic polyQ-Htt, eliciting a depletion of NAD levels and accumulation of NaMN. In parallel a downregulation of Sirt2 expression levels has been observed. Phenolic extract administration had no meaningful ef-fects on NAD replenishment to prevent proteotoxicity. NaMN can represent a biomarker of accel-erated aging, and/or a signaling molecule for cell repair.