MAPT and Atrophy: Another study in early PD with and without CI found associations between radial distances as a measure of atrophy in CA1, CA3, and subiculum, and poorer verbal recall and recognition, suggesting that these functions are impaired at least partly due to structural hippocampal changes.16 They did not find any significant associations between CSF amyloid or tau species and hippocampal radial distance thickness.33 The discrepancies with our study may be due to the use of different segmentation techniques, radial distance mapping, and neuropsychological tests.