APOE and Cognitive impairment: Specifically, NGF mediated the association between APOE ε4 and Animal Fluency Test score (β, -0.45; 95% CI [-0.96, -0.07]; p < 0.001) and Trail Making Test-A (time) (β, 0.15; 95% CI [0.01, 0.33]; p < 0.001).<h4>Conclusion</h4>APOE ε4 is associated with cognitive impairment, and those carrying APOE ε4 have decreased NGF level in CSF.