IFNG and Alzheimer disease: Furthermore, the IL-18, IFN-γ, IL-6, Glu, CREA, and D-dimer levels; gender; and smoking status were used to perform multivariate linear regression analysis, and the results showed that the IL-18 level was independently associated with the presence of AD (β = 0.238, 95% confidence interval (CI) 0.053 to 0.422; P = 0.012).