MAPT and Schnyder corneal dystrophy: Previous studies have shown that CU older adults with high levels of Aβ and tau,29, 30, 73 or with high levels of Aβ and SCD,31, 32, 33, 34, 35 have a higher risk of future cognitive decline and may be at a more advanced stage of the disease, compared to those with high Aβ alone who may never experience cognitive decline during their lifetime.74