MAPT and early-onset autosomal dominant Alzheimer disease: Disturbed tau function would be expected, then, to have wide-ranging effects in the brain, and tauopathies do usually affect cognition, language, behavior and movement to varying degrees, as is the case with Alzheimer’s disease (AD), frontotemporal dementia due to tauopathy, progressive supranuclear palsy and corticobasal degeneration6,7.