HTR4 and Alzheimer disease: Several other studies have also indicated that 5-HT4R agonists (e.g., RS6733, a partial agonist) inhibit the production of Aβ in the entorhinal cortex, a region of deterioration in early-stage AD (Gale et al., 2018), by promoting the production of the neurotropic soluble APP alpha (sAPPα) and helps in improving cognitive abilities (learning and memory) in animal models of AD (Baranger et al., 2017; Yahiaoui et al., 2016).