Abstract: This invention provides a method for determining whether a human subject is afflicted with AD or non-ADD when the subject is suspected of being afflicted with AD or non-ADD, comprising the steps of (a) synchronizing a population of suitable cells derived from the subject; and (b) in the resulting synchronized cell population, measuring the expression level of a gene known to be differentially expressed between corresponding synchronized cells derived from AD patients and those derived from non-ADD patients, whereby (i) the subject is afflicted with AD if the expression level measured in step (b) is consistent with that gene's expression level in corresponding synchronized cells derived from AD patients, and (ii) the subject is afflicted with non-ADD if the expression level measured in step (b) is consistent with that gene's expression level in corresponding synchronized cells derived from non-ADD patients. This invention also provides diagnostic methods based on NDS patient gene expression levels.