Metformin treatment was shown to inhibit neuronal loss, the direct cause of cognitive deficits in AD, by promoting neurogenesis and inhibiting pathological neuronal apoptosis in the hippocampus of amyloid precursor protein/presenilin-1 (APP/PS1) mice (West et al., 1994; Ou et al., 2018). This evidence concerns the gene PSEN1 and Alzheimer disease.