TTBK1-IN-1 is a highly potent and selective inhibitor of tau tubulin kinase 1 (TTBK1), capable of penetrating the blood-brain barrier with ease. With an IC 50 value of 2.7 nM, TTBK1-IN-1 exhibits strong inhibitory activity against TTBK1. This compound holds great promise for advancing research in Alzheimer's disease and other tauopathies.