TH and Parkinson disease: Interestingly in the MMD, MMD-LB and PD groups, nigral neurons that contained tau aggregates showed a significant reduction in TH immunofluorescence intensity (70.83% for MMD, 69.61% for MMD-LB and 70.88% for PD) relative to the NMD group (P < 0.001; Fig. 6M).