To validate biomarkers identified in this work, we tested their coherence and predictive power in the context of independent gene expression dataset, GSE1572 [3]. This data set contained gene expression data from PFC samples of 30 non-demented subjects, aged 26–106. These samples were profiled on Affymetrix Human Genome U95 Version 2 Array (GPL8300). To select the probes and calculate the biomarker score, we matched the biomarker gene symbols to those represented on the HG-U95Av2 array. We calculated the correlation of the expression level of each selected probeset with the composite biomarker score (see above) and refined the selection by dropping probes that demonstrated opposite regulation according to the sign of the correlation coefficient. Finally, we correlated the biomarker scores with the subject age.
