TREM2 and Parkinson disease: The correlations between disease progression and TREM2 level in the putamen of PDD patients (Figure S3, rs = 0.786, p = 0.036), as well PD stage and TREM2 level in the putamen of LBDs (Figure S4, rs = 0.421, p = 0.036) further supported the association between microglial phenotype and disease progression [41].