P1‐246: BASELINE BIOMARKERS ARE MORE ACCURATE THAN LONGITUDINAL CHANGE OF BIOMARKERS IN PREDICTING COGNITIVE DECLINE. (1st July 2019) - Chen, Gengsheng; Gordon, Brian A.; Liu, Jingxia; LaMontagne, Pamela J.; Keefe, Sarah; Dincer, Aylin; Morris, John C.; Benzinger, Tammie L.S.