Increased expression of TREM2 in peripheral blood of Alzheimer's disease patients.

TREM2 has been reported to be associated with Alzheimer's disease (AD). Here, we evaluated TREM2 mRNA and protein expressions in peripheral blood from AD patients and healthy controls. Higher levels of TREM2 mRNA (p = 0.002) and protein (p < 0.001) were identified in AD patients. We observed a significant correlation between TREM2 expressions and MMSE score (mRNA: r = -0.482, protein: r = -0.582; p < 0.01). According to ROC curve analysis, the diagnostic accuracy for TREM2 protein levels on monocytes was 70%, with the sensitivity and specificity 68% and 72%, respectively. Our results indicate that TREM2 might serve as a novel noninvasive biomarker for AD diagnosis.