MAPT and Alzheimer disease: In systematically testing for evidence of this, we show that ROCK1 is a target of microRNA-146a in neural cells, that overexpression of microRNA-146a in neural cells induces tau hyperphosphorylation via ROCK1 regulation through PTEN, that there is a reduction in ROCK1 levels and a colocalisation with hyperphosphorylated tau in neurofibrillary tangles in the brains of patients with AD, and that inhibiting microRNA-146a in a validated mouse model of AD reduces tau hyperphosphorylation and enhances memory function.