“…Later, as pathology involves the neocortices including higher association areas, individuals with PD and "normal" cognition (PD-N) may cross a barrier of barely detectable cognitive problems and develop neuropsychologically classifiable mild cognitive impairment (PD-MCI) and eventually the full picture of dementia (PDD) (Braak et al, 2003;Braak & Del Tredici, 2017). A large body of in vivo evidence supports the staging system (Zarei et al, 2013;Zeighami et al, 2015), although it is not without controversy (Surmeier, Obeso, & Halliday, 2017;Walsh & Selkoe, 2016). By definition, longitudinal studies from postmortem material are not possible, hence, tracing the temporal dynamics of pathology patterns in vivo together with clinical features becomes increasingly important (Fereshtehnejad, Zeighami, Dagher, & Postuma, 2017).…”