Objectives: To clarify that correlation in plasma soluble TREM2 (sTREM2) and cognitive function between mild cognitive impairment (MCI) and normal cognitive function in a Chinese community population, and further to explore whether plasma sTREM2 can be used as a blood biomarker to predict and identify MCI.

Methods: This study included 216 community elderly people in Shijiazhuang and Xingtai City, Hebei Province, including 106 MCI and 110 normal cognitive function (NC) subjects. The Montreal cognitive assessment (MoCA) was used, mini mental state examination (MMSE), Boston naming test (BNT), digit span test (DST) to evaluate the cognitive functions of all subjects. Fasting venous blood was collected at the same time, and ELISA was used to detect Aβ42, Aβ40, P-Tau217, P-Tau231, TREM2, sTREM2 concentration. Use software based on SPSS26.0 to analyze the data.

Results: 1. The level of sTREM2 in the MCI group was higher than that in NC group, and the difference was statistically significant (H = 4312.0, P = 0.001). There was no statistical significance in the difference of the other index between two groups (P > 0.05). 2.Correlation analysis showed that sTREM2 was negatively correlated with P- tau217, education level, MMSE, MoCA, BNT, and DST (P < 0.05). TREM2 was positively correlated with P-tau217 and Aβ42 (P < 0.05). 3. Incorporate whether it was MCI as the dependent variable, gender, age, education level, living style, and the above blood indicators as independent variables in binary logistic regression analysis. The results showed that sTREM2 was a risk factor for MCI (OR = 1.009, 95%CI = 1.002– 1.016, P = 0.015), junior high school education or above was a protective factor for MCI (OR = 6.133, 95 % CI = 2.651–14.189, P < 0.001). 4.The area under the ROC curve of sTREM2 was 0.630 (sensitivity 0.472, specificity 0.782), and the area under the ROC curve of sTREM2 combined with MMSE was 0.849 (sensitivity 0.679, specificity 0.873).

Conclusions: sTREM2 is a risk factor for cognitive function decline in MCI. Plasma sTREM2 levels combined with the cognitive function assessment scale have good clinical value in identifying mild cognitive impairment.