MAPT and Alzheimer disease: In PD and in other synucleinopathies (Box 1), α-synuclein concentrations in the CSF are typically lower than in healthy controls (Hall et al., 2012; Mollenhauer et al., 2011), whilst in AD and CJD, its concentrations are increased and correlate with T-tau, indicating that α-synuclein might also be a nonspecific marker of neurodegeneration (Mollenhauer et al., 2011; Öhrfelt et al., 2009; Slaets et al., 2014; Tateno et al., 2012; Wennström et al., 2013).