We studied APOE genotype effects on the cerebrospinal fluid (CSF) proteome.<h4>Methods</h4>Using untargeted tandem mass tag mass spectrometry, we analyzed CSF from 227 cognitively normal (CN) controls (A-T-), 165 CN A+, and 177 individuals with mild cognitive impairment (MCI A+) from two large cohorts. Here, APOE is linked to Cognitive impairment.