Using a combined post-mortem insitu MRI and histopathology approach, we investigated the associations between MRI cortical thickness and Aβ, p-tau and reactive microglia load in clinically-defined and pathologically-confirmed Alzheimer’s disease and control donors, and explored these associations in typical and atypical Alzheimer’s disease phenotypes. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.