IL17A and Alzheimer disease: With a cut-off value of >1.004, the CSF IL-6/IL-17A ratio could discriminate SSVD from controls and AD patients, with high (over 80%) sensitivity (83.33%), but modest specificity (68.97%), according to the Working Group on Molecular and Biochemical Markers of AD, Reagan Research Institute of Alzheimer’s Association and National Institute on Aging (1998) [47].