SCFAs have been reported to activate FFAR3 (previously termed GPR41), FFAR2 (previously termed GPR43), and GPR109a, with FFAR2 agonists shown to ameliorate DNCB-induced AD in mice (Moniri and Farah, 2021; Kang and Im, 2020). Here, FFAR2 is linked to Alzheimer disease.