MAPT and Parkinson disease: Some studies suggested the utility in discerning PSP from HC, with lower uptake in the substantia nigra in both PSP and PD patients; however, difficulties arose in differentiating PSP from PD due to overlapping binding patterns given that there is comparable tracer uptake distribution in particular for brain regions linked with tau pathology, such as the midbrain and globus pallidus [43,72,74].