MAPT and Alzheimer disease: Conversely, patients with the language variant of AD commonly (~30%) present with some visual dysfunction, including visuospatial/perceptual deficits (Tippett et al., 2020; Foxe et al., 2021; Tee et al., 2022), simultanagnosia and Gerstmann syndrome (i.e., features of the visual variant of AD), which is related to atrophy and tau deposition developing in the parietal and occipital lobes (Singh et al., 2023).