NLK and Alzheimer disease: Furthermore, in n = 28 aMCI/AD patients with positive AD biomarkers (A+T+(N+)) the mean CSF NLK concentration (5.21 ± 1.08 ng/ml) was higher than in n = 20 controls with normal AD biomarker status (A−T−(N−); 2.72 ± 1.0 ng/ml; when adjusted for age and sex (p < 0.0001; Fig. 1C), and after additional adjustment for total protein (p < 0.0001).