SIRT1 and neurodegenerative disease: Firstly, the previously uncharacterized transcriptional regulation of SIRT1 on sphingomyelin degradation directly links cellular levels of sphingomyelin and membrane fluidity with cellular energy status, and provides a possible molecular mechanism for the beneficial impacts of SIRT1 small molecule activators and/or NAD+-boosting dietary supplements on human neurodegenerative diseases.