MAPT and Alzheimer disease: These findings are in broad agreement with the literature showing an association between CSF tau and brain morphological measures across PD (Beyer et al., 2013, Compta et al., 2012), MCI, and AD (Solé-Padullés et al., 2011, Thomann et al., 2009), and further implicate tau as an important component of neurodegeneration in PD.