MAPT and Alzheimer disease: Importantly, when the same model was applied to classify AD versus non-AD patients without stratifying by tau status, its performance dropped significantly and misclassified 8 out of 42 patients (supplemental Fig. S5) indicating that while machine learning can effectively discriminate AD patients from non-AD controls, its full potential is realized when biologically relevant subgroups, such as Aβ+/tau+ and Aβ+/tau- AD, are considered in the classification strategy.