Besides, several 5-HT6 antagonist drugs, such as Pfizer's SAM-760 and SAM-531, Abbott's A-964324, Avineuro Pharmaceuticals' AVN-322, Suven's SUVN-502, Synosia Therapeutics' SYN-120, idalorpidine, and others, showed no significant positive effects for AD patients [7]. Here, HTR6 is linked to Alzheimer disease.