SIRT1 and Alzheimer disease: Knowing that miR-34a had been shown to target the transcript for SIRT1 in human colon cancer cells [148], the authors hypothesized that the previously reported up-regulation of miR-34c in AD may lead to decreased production of SIRT1 in the hippocampus, and thus diminished performance in memory-based tasks due to the fact that SIRT1 production in the hippocampus had been correlated with memory formation and learning in mice.