Whereas regional summary measures of 18F-RO-948 sampled from regions associated with Braak stages outperformed measures of p-tau 181 in distinguishing AD, healthy controls and non-AD patients, ratio measures of both CSF Abeta 40/Abeta 42 and CSF Abeta 42/p-tau 181 showed better discrimination performance for the comparison of MCI (amyloid positives) vs. non-AD disorders. The gene discussed is MAPT; the disease is Alzheimer disease.