Several drugs intended as indirect α-secretase activators have progressed to the clinical trial stage for AD, such as GABA receptor modulator etazolate, 5-HT4 agonist PRX-03140, and a polyphenolic compound from green tea, epigallocatechin-gallate, but no results have been published to date (NCT00880412, NCT00693004, NCT00951834). Here, HTR4 is linked to Alzheimer disease.