MAPT and red-green color blindness: Tau protein is associated with Alzheimer disease (AD), Pick disease (PiD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), argyrophilic grain disease (AGD), and globular glial tauopathy (GGT) [5,6], and aged people often have neuronal or glial tau pathology [7,8]; these conditions are termed tauopathies.