NEFL and Alzheimer disease: The optimal cut-off value for diagnosing AD (i.e., NfL > 40.9 pg./mL, GFAP >31.40 pg./mL), sensitivity, specificity, predicted value, likelihood ratio and other indicators of single detection and combined detection of each indicator can be obtained (shown in Table 5); among these indicators, serum GFAP has higher sensitivity and specificity while combined diagnosis improves the specificity of AD diagnosis.