In the second step of analyses, aimed at identifying the first cognitive deficits associated with a pathologic change in AD, we specifically examined the relationship between Aβ pathology and cognition in individuals where no signs of abnormal tau or neurodegeneration were present (i.e., using the A−T−[N]− and A+T−[N]− subgroups; n = 217 for CSF-based model, n = 246 for PET-based model). The gene discussed is MAPT; the disease is Alzheimer disease.