MAPT and Alzheimer disease: Hence, under the hypothesis that the effects of AD and non-AD co-pathologies, reflected in cortical and hippocampal degeneration, on cognition are cumulative [9], it is conceivable that ‘pure’ AD, which entails less hippocampal atrophy than AD+, would result in more extended tau pathology and atrophy in cortical intermediate Braak stage areas in MCI and mild dementia.