The treatment of abnormal hyperphosphorylation of tau in brains of patients with metabotropic glutamate receptor 5 (mGluR5) antagonists. The treatment uses the signaling pathway in which the inhibition of protein phosphatase 2A (PP2A) through phosphorylation of its catalytic subunit PP2Ac at Tyr307 is induced by the activation of metabotropic glutamate receptor 5 (mGluR5) and leads to hyperphosphorylation of tau. The mGluR5-PP2A axis has a central role in neurofibrillary degeneration and thus is be a therapeutic target for the treatment of tauopathies.