Herein we describe the discovery of an orally brain-22 permeable small-molecule, DDL-218, that enhanced SirT1 in ApoE4-expressing neuronal cells 23 and a murine AD model. DDL-218 increased the transcription factor NFYb resulting in 24 upregulation of PRMT5. Mechanistic and modeling studies show that binding of ApoE4 to the 25 SirT1 gene promoter can be displaced by PRMT5 leading to increased SirT1 transcription. DDL-26 218 treatment elicited improvement in memory in the AD model, suggesting that DDL-218 27 enhancement of neurotrophic SirT1 in the brain has potential to modulate neuronal activity that 28 may clinically provide an improvement in cognitive function and complement the current anti-29 Aβ antibody monotherapy. Our findings support further development of DDL-218 as a novel 30 ApoE4-targeted therapeutic candidate for AD.