MAPT and Alzheimer disease: However, several, if not all, studies have reported that metformin may trigger AD pathology in rodent models; metformin increases the expression of β-amyloid (Aβ) via beta-secretase 1 (BACE1) upregulation in C57BL/6 mice as well as in a transgenic AD model, 3xTg-AD mice [9] and promotes tau aggregation in mice with tauopathy [10].